Food Waste Management: A Case of Taiwanese High School Food Catering Service

Abstract

This study aims to understand the current state of food waste in Taiwanese school food catering services and the causal configurations that make school food waste possible, as food waste management has generated considerable concern. Combining document analysis, direct weighing, observation, and semi-structured interviews, a mixed methodology was employed to collect data. In order to comprehend and quantify food waste, the amount of school lunch provided and food waste during a 35-day period were measured, as well as the inefficiency index of lunch food at the two schools. According to this study, the inefficiency index of all dishes offered at Y Senior High School by the same lunch caterer is lower than at X Girls High School. In addition, this study identifies seven factors that contribute to school food waste, comprising meal quality, rigid budget limitation, tracking and feedback system, unforeseen factors, partial eating behavior, environmental awareness, and lack of initiatives for reducing food waste. This research also proposes five strategies to improve the management of contracted catering companies in schools, thereby reducing school lunch waste from supply sources. Taiwan’s experience can serve as a model for countries in comparable situations and academically fills the gaps in the experiences of varied societies.

1. Introduction

According to new United Nations research undertaken to assist in global efforts to halve food waste by 2030, an estimated 931 million tons of food (equivalent to 17% of all food available to consumers) was discarded by families, retailers, restaurants, and other food services in 2019 [1,2]. The Food Waste Index Report 2021 indicates that the majority of this waste is generated by households, which squander 11% of all food available at the consuming stage of the supply chain. Food services and retail outlets waste 5 % and 2%, respectively [3]. Even though food services accounted for only 5% of waste, 66% of edible waste was generated, demonstrating that avoidable food waste accounted for a rather significant amount [3]. According to the statistics mentioned previously, a substantial proportion of food waste in the food service industry can be minimized further. Therefore, many countries have also implemented measures to prevent food waste in food services. Nonetheless, numerous studies have revealed that food waste still exists in school food catering services and that further incentives are required to urge them to continue reducing food waste [4,5,6].

Malefors et al. [6] indicated that between 19,000 and 21,000 tons of food waste were produced yearly in Swedish preschools and schools in 2020. García-Herrero et al. [7] found that 20–29% of the prepared meal was wasted in Italian schools, and food waste accounted for 6–11% of the costs. According to a report by Liberty Times Net [8], students in 100 public and private schools in Taipei City discard 17,000 boxes of school meals every day, generating as much as 10 metric tons of food waste daily. These surveys demonstrated that the issue of food waste in school food catering services has become an essential concern for the reduction in food waste. In addition, while 821 million people are hungry and 3 billion cannot afford a healthy diet, food waste occurs [9]. This discarded food also contributes to 8% to 10% of the world’s greenhouse gas emissions. School food waste even reflects students’ nutritional imbalance and the problem of partial eating [4,10]. Consequently, food waste has substantial environmental, social, and economic impacts.

Promoting schools with independent kitchens is currently one of the most important initiatives in Taiwan, as governments want to improve school lunch quality and control the source of food to deliver delicious and nutritious school meals. However, due to a shortage of manpower and professional expertise, the primary method of lunch management in schools with independent kitchens in Taiwan is currently outsourced [11]. Previous research indicates that outsourcing non-core functions such as catering services allows educational institutions to concentrate their resources on their core business, which is the provision of educational services [12]. Schools can also utilize their purchasing power to request that caterers use eco-friendly goods, in order to contribute to environmental progress. However, food waste in schools continues to be a significant problem [4,5,6].

Prior research has focused on the causes of food waste in schools in an attempt to decrease food waste. Poor demand planning, cooking waste and scraps, plate leftovers, and expired ingredients are the primary waste drivers in schools’ independent kitchens [13]. According to Weng [14], the restrictions and obstacles of the operation of the catering company have a direct impact on the quality of school meals, such as limited budgets that restrict lunch variations and ingredient selection in Taiwan. The taste and diversity of food will directly influence students’ willingness to consume school meals [15,16]. Derqui et al. [17] even demonstrated that schools’ headteachers erroneously believe their canteens are efficient at modifying the amount of food cooked and that their students leave little food on their plates. Consequently, the leadership’s visibility and awareness of the issue of food waste and operation management will have an effect on school sustainability. Prior research measured the amount of food waste on student plates [10,18,19] and identified two strategies for minimizing food waste: reducing portion sizes, and the composition and presentation of meals [5,18,19]. In addition, research has shown that the recycling and redistribution of unserved food in schools is an effective initiative to reduce food waste [5,20]. Sustainable food education has also been identified as a crucial aspect; schools and families must make greater efforts in this area [5,19,21,22].

School lunches constitute a unique environment due to their capability to convey food habits and manage available resources in a sustainable manner. In order to boost the sustainability of educational institutions, substantial work is required. This study selected and analyzed two high schools in Taipei with independent kitchens managed by a contracted catering company, using a quantitative investigation and a qualitative interview. Malefors et al. [6] and Silvennoinen et al. [23] suggested that school canteens require appropriate tools to monitor waste levels and progress in order to reduce overproduction and enhance meal planning. To successfully address the problem of food waste in schools, it is also necessary to explore its causes. Therefore, the current study has two main purposes: (1) to use a direct weighing method to calculate and analyze the quantity of food waste in school based on previous studies [5,24]; (2) to conduct interviews with stakeholders, such as the contracted caterer, school administrators, and students. This study’s quantitative findings not only help in understanding the holistic food intake and waste of high school students, but they can also be utilized as evidence to adjust the quantity and content of meals in order to prevent over-preparation and food waste. A qualitative interview could expand our findings and help us identify the factors that contribute to lunch food waste among students. Understanding the causes of student food waste not only provides schools with practical strategies for improving the management of school lunches, but also improves the meal quality of school lunches to enhance the operational performance of the contracted catering firms.

2. Literature Review

2.1. Food Catering Service

The hospitality and food services sector includes all establishments that provide food and/or beverages for immediate consumption outside the home. It consists of various sub-sectors, including restaurants, education, healthcare, hotels, and staff catering [25]. Catering is the provision of a food service to institutions such as hospitals, army barracks, schools, and universities [12]. In Europe, the food service sector consists of a large number of public catering establishments that supply food to preschools, schools, hospitals, and care homes for the elderly [22,26]. Therefore, food catering services are an essential component of the hospitality and food services sector.

In Taiwan, school food catering services include three types: public-owned and public-managed, public-owned and outsourced-managed, and packed lunches. The first two groups correspond to schools with independent kitchens and self-managed or outsourced catering services to deliver lunch to their students, as well as schools in close proximity. The term “independent kitchen” refers to the storage, preparation, cooking, and serving of food in situ in the school’s facilities [13]. Packed lunches are provided in schools that lack kitchens, and schools rely on specialized catering companies to prepare school meals [9]. Clearly, catering companies have an important function in the catering services of Taiwanese educational institutions.

Since catering services at academic institutions feature a number of characteristics suitable for business process outsourcing [27], school food service outsourcing is a popular practice in Taiwan [11]. Given that catering services account for a significant portion of public spending, they have been designated as one of the sectors that may significantly contribute to public sector environmental development [28]. In particular, when public authorities are able to use their purchasing power to select ecologically friendly products, they have a considerable opportunity to improve environmental performance.

2.2. School Lunch Food Waste

2.2.1. Food Waste Measurements

According to the United Nations Environment Programme [3], food waste is defined as food and the associated inedible parts removed from the human food supply chain in retail, food services, and households. Food waste includes two categories: edible parts, i.e., the parts of food that were intended for human consumption, and inedible parts, i.e., components associated with a food that is not intended to be consumed by humans (e.g., rinds and fruit skin) [19]. Additionally, according to a study conducted by Papargyropoulou et al. [29], discarded food that is edible, or a portion of edible food, is also known as avoidable food waste. Unavoidable food waste is described as food that is and has been inedible under normal conditions. This study aims to investigate the extent and causes of food waste among high school students who consume school lunches. Numerous Taiwanese school lunches contain meat with bones (e.g., steak, chicken) and fruits with skins (e.g., watermelon, orange), making it difficult to distinguish between edible and inedible parts when assessing weight. Therefore, this study defines food waste as the sum of edible and inedible components (i.e., avoidable and unavoidable food waste) [29].

Food waste monitoring is vital for rebalancing the current unsustainable food system and transforming it into one that is equitable, healthful, and environmentally friendly [30]. According to previous research on school lunch waste, there are four ways to measure lunch leftovers: in-person visual estimation, digital photography, direct weighing, and a combination of two or more of the above methods [24]. The direct weighing method is used to acquire reliable data on leftover food through real weighing, and its accuracy is so high that it has become a prominent measurement technique for many related studies [5,6,31]. In previous research, prepared food, plate leftovers, and unserved food were weighed and measured separately for each meal course using an electronic scale to determine the extent of food waste [31]. Plate waste comprises three kinds, namely individual plate waste, aggregated nonselective plate waste, and aggregated selective plate waste. Individual plate waste refers to the direct measurement of the amount of individual food left on the student’s plate. Aggregated nonselective plate and aggregated selective plate waste refers to the method of collecting leftover food from students’ plates and measuring the amount of leftovers, but aggregated selective plate waste further classifies and quantifies them based on the type of food [32].

According to studies measuring food waste, food waste in schools has led to operational inefficiency and economic loss [4,5,6]. Cohen et al. [4] evaluated the food consumption and lunch leftovers of four middle school students in the United States. They found that the actual consumption of school meals was less than the standard proportion of 85%, and leftovers accounted for approximately 26.1% of the food budget. It is estimated that food waste annually represents a loss of approximately USD 1.2 billion. Malefors et al. [6] evaluated food waste data obtained from Swedish public catering firms that offer meals to preschools, schools, and care homes and found that between 19,000 and 21,000 tons of food were thrown out yearly in schools in 2020. In order to accurately calculate the weight and proportion of different types of leftovers, some researchers measure the weight of each food before students consume it to precisely compute the percentage of the inefficiency index [5]. Falasconi et al. [5] measured the weight of prepared food and non-served food in order to calculate the food inefficiency index for three Italian primary and three secondary schools. The results of the study indicated that the management of the catering service was inefficient, as evaluated by the amount of food that was prepared but not served. This quantity accounted for an average of 15.31% (6523.35 kg) of all prepared foods. In conclusion, the aforementioned study showed that food waste in schools has long been a significant issue, and tracking its amount is a vital way to understand the accurate scale of food waste and its impacts.

2.2.2. Factors That Contribute to Food Waste

In order to effectively address the problem of school lunch waste, studies have concentrated on the factors that contribute to food waste [5,15,31]. Chen et al. [15] identified five factors that affect school lunch satisfaction in Taiwan, including dish variety, dining environment, hygiene, freshness, and cooking skills. Falasconi et al. [5] determined the future causes of school lunch waste: (i) menu composition: some menus include items with comparable characteristics (e.g., bread and pizza) that should be considered alternative dishes; (ii) rigid procurement practices: the standard quantity of each food item cannot be modified easily; (iii) inattention to dietary patterns: families are not concerned about the dietary practices of their children; (iv) meal presentation: food is displayed in an unappealing manner. Boschini et al. [31] discovered that foodservice providers have the greatest impact on school food waste. Other characteristics were the amount of food produced and the portion size, the location of the kitchen, the food offered for the mid-morning break, the structure of the menu, and the geographical area. Other research has provided solutions to the problem of school waste [19,21,22]. Silvennoinen et al. [19] emphasized that offering sufficient eating time and enhancing food and sustainability education are the most effective approaches to eliminating school leftovers. Malefors et al. [22] stressed that attendance forecasting is an effective method for reducing serving waste, and plate waste trackers and awareness campaigns are efficient methods for reducing plate waste in school canteens. Izumi et al. [21] identified the following five strategies from Tokyo elementary schools to reduce lunch waste: the reinforcement of social norms to consume food sparingly; planning meals to enhance exposure to unusual and/or disliked foods; food and nutrition instruction incorporated into the school curriculum; classroom practices related to portion sizes, leftover food distribution, and time management during lunch; and the participation of students in decreasing school lunch waste.

3. Methodology

3.1. The Measurement of Food Waste

This study utilized purposive sampling to choose sample schools as research cases. A combination of document analysis, direct weighing method, observation, and semi-structured interviews was used at different stages of this study to determine the degree of school lunch waste in sample schools and to investigate the factors driving food waste. Figure 1 depicts the study’s procedure. The sample schools were chosen because each has an independent kitchen managed by the same outsourcing company, which is beneficial for controlling the lunch menu and meals served. Two schools were selected: X Girls High School (n = 1450, female = 1450) and Y Senior High School (n = 1750, female = 698, male = 1052). The two schools are both private high schools in Taipei City with grades ranging from 7 to 12, and their student populations are relatively comparable. This study started by analyzing the catering company’s documents and records related to school lunch catering (e.g., lunch menus, meal serving records, and discarded food records). The researchers then measured the weights of prepared food and student food waste (unserved food and plate leftovers were combined in the calculation) at the two schools for a total of 35 days as a menu cycle. The lunch menus consisted of the same food categories in both schools, including rice or noodles, main dishes (fish or meat), side dishes (vegetables and other foods), and fruits. Student food waste includes food left in the food bucket (prepared but not served) and leftovers from the student’s plate [19]. The evaluation of food waste was conducted on a direct measurement made during lunchtime in kitchens and student cafeterias. According to Boschini et al. (2020) [31], the collection of data included catering providers, teachers, and students. The catering employees weighed the prepared (served) food each day, and data were recorded. The students themselves independently sorted the leftover food from their plates into four separate containers (one container for each course). At the conclusion of lunch, the catering employees sorted the remaining food in the food bucket (prepared but not served) into the same four food category containers, then weighed and recorded the individual food categories in each container. The schools were given the required supplies, including plastic containers for the separate collection of food waste, illustrations to be affixed to the containers to aid students in the correct separation of the plate remains from different courses, and an electronic scale. Before the study period, teachers and catering employees were informed about quantification procedures and given paper guidebooks with thorough instructions.

3.2. The Investigation of Lunch Food Waste Factors

The researchers observed students’ dietary behaviors during lunch and conducted interviews with 28 participants, including eight teachers, two dieticians, fifteen student representatives, and three senior managers of the catering company, in order to investigate the factors that contribute to lunch food waste from the perspectives of the school, the student, and the lunch provider. This study adopted purposive sampling to select participants. To be eligible for the study, the participants had to meet the following selection criteria: (a) 18 years or older, (b) sample schools’ teachers, students, dietician and food service providers, and (c) participants who are acquainted with the school lunch operation procedure and actually consume school lunches. Before conducting the interviews, the fifteen student representatives were asked to collect the opinions of their classmates. Hence, they reflect not just the individual but also the collective ideas of students. Based on the existing literature [5,15,19,21,22,31], several questions concerning waste awareness and attitude, waste behavior and causes, and strategies to prevent food waste were included in the interview guides. The interview consisted of three sections, including questions pertaining to perceptions of school lunch waste consciousness and attitude, student waste behavior and factors driving food waste, and methods and strategies for reducing food waste.

Table 1. Demographic information of the respondents.

School	Code	Gender	Identity	School	Code	Gender	Identity
X Girls High School	A01	Male	Senior manager	Y Senior High School	B01	Male	Senior manager
	A02	Male	Senior manager		B02	Female	Teacher
	A03	Female	Teacher		B03	Female	Teacher
	A04	Female	Teacher		B04	Female	Teacher
	A05	Female	Teacher		B05	Female	Teacher
	A06	Female	Teacher		B06	Female	Dietician
	A07	Female	Dietician		B07	Male	Student
	A08	Female	Student		B08	Female	Student
	A09	Female	Student		B09	Male	Student
	A10	Female	Student		B10	Male	Student
	A11	Female	Student		B11	Female	Student
	A12	Female	Student		B12	Male	Student
	A13	Female	Student		B13	Male	Student
	A14	Female	Student		B14	Female	Student

shows the profiles of the respondents.

4. Results

4.1. The Analysis of Food Waste

The inefficiency index refers to the proportion of school lunches that are discarded without being consumed. It is evaluated as a ratio of discarded food compared to the amount of served food [5]. Consequently, the inefficiency index would increase in proportion to the number of uneaten and discarded meals. The amount of each food category that is discarded is determined by combining the amount of unserved food that is prepared but not served with the amount of food left on each student’s plate. For X Girls High School (see

Table 2. Served food (kg) and discarded food (kg and %) of X Girls High School.

Category	Served Food			Discarded Food			Inefficiency Index
	Total kg	Average kg per Day	Average Portions per Day	Total kg	Average kg per Day	Average Portions per Day	(%)
Rice and noodles	8474.10	242.12	0.17	2365.00	67.57	0.05	27.91%
Main dishes (fish or meat)	7835.41	223.87	0.15	1820.00	52.00	0.04	23.23%
Side dishes (vegetables and other foods)	7524.29	214.98	0.15	2294.00	65.54	0.05	30.49%
Fruits	6280.70	179.45	0.12	1126.00	32.17	0.02	17.93%
Total	30,114.49	860.41	0.59	7605.00	217.29	0.15	25.25%

Note: Total kg: total weight measured over 35 days. Average kg per day: the total weight divided by the number of measurement days. Average portions per day: average weight per day divided by the number of students. Inefficiency index: the total weight of discarded food divided by the total weight of served food.

), the inefficiency index represented an average of 25.25% (7605 kg) of the overall served food. In terms of different food categories, the inefficiency index of side dishes (including vegetables and other foods such as tofu, eggs, and other processed products) accounted for 30.49% (2294 kg) of its kind, indicating the highest percentage of wasted food. Next, rice and noodles were also characterized by a high percentage of food waste, accounting for 27.91% (2365 kg) of its category. However, main dishes and fruit presented results below the average inefficiency index, respectively, accounting for 23.23% (1820 kg) and 17.93% (1126 kg) of their category. The inefficiency index of side dishes, rice, and noodles can be explained by their meal combination (see

Table 3. Menu items by day of the week.

Category	Monday	Tuesday	Wednesday	Thursday	Friday
X Girls High School
Staple	rice	rice	rice	rice	assorted fried noodles
Main dishes	chicken	pork and fish	chicken	chicken	chicken
Side dishes	beansprouts with pork, cabbage, tempura (starch-processed foods)	seaweed, vegetable	mung bean noodles with ingredients, eggs, spinach	kimchi with meat, vegetable, cucumber	rape
Fruits	apple	tomato	melon	banana	apple
Y Senior High School
Staple	rice	rice	rice	rice	pasta
Main dishes	pork	chicken and fish	pork	pork	chicken
Side dishes	corn, tofu assorted vegetable	cabbage, vegetable	sausage, vegetable, braised assorted vegetable	corn, vegetable, steamed dumplings	chicken nugget
Fruits	watermelon	melon	papaya	dragon fruit	guava

). Rice-satisfying items, such as starch-processed foods and mung bean noodles, are commonly accompanied by side dishes. This combination would decrease staple food intake, since students would consume these foods prior to rice and noodles. For Y Senior High School (see

Table 4. Served food (kg) and discarded food (kg and %) of Y Senior High School.

Category	Served food			Discarded Food			Inefficiency Index
	Total kg	Average kg per Day	Average Portions per Day	Total kg	Average kg per Day	Average Portions per Day	(%)
Rice and noodles	7476.00	213.60	0.12	1329.00	37.97	0.02	17.78%
Main dishes (fish or meat)	10,297.00	294.20	0.17	1184.00	33.83	0.02	11.50%
Side dishes (vegetables and other foods)	7642.00	218.34	0.12	875.00	25.00	0.01	11.45%
Fruits	5147.00	147.06	0.08	1108.00	31.66	0.02	21.53%
Total	30,562.00	873.20	0.50	4496.00	128.46	0.07	14.71%

Note: Total kg: total weight measured over 35 days. Average kg per day: the total weight divided by the number of measurement days. Average portions per day: average weight per day divided by the number of students. Inefficiency index: the total weight of discarded food divided by the total weight of served food.

), the inefficiency index represented an average of 14.71% (4496 kg) of the overall served food. Fruits had the highest percentage of food waste, accounting for 21.53% (1108 kg) of their category. Rice and noodles also accounted for a high percentage of food waste (17.78%, 1329 kg). However, main dishes and side dishes presented results below the average inefficiency index, respectively, accounting for 11.50% (1184 kg) and 11.45% (875 kg).

An identical menu structure (including meal composition, taste, and quality) from the same provider resulted in greater food waste at X Girls High School compared to Y Senior High School. School policies and recycling regulations are highly related to the inefficiency score’s performance. X Girls High School has an additional demand that the operator must produce extra quantities of side dishes for students who need to consume more food, and this requirement is one of the most essential indications for assessing the performance of the catering company. Y Senior High School encourages students to place food they do not like or have not eaten on the public counter so that students who need more food can take it and eat it. In this way, the objectives of food sharing and waste reduction are achieved. Moreover, gender can explain the variation in the inefficiency index between the two schools. X Girls High School comprises only female students, whereas Y Senior High School comprises both male and female students. According to previous research, male students throw away less food from their plates, and gender affects food choices and preferences [33,34]. Female students prefer fruits and high-fiber diets and avoid foods rich in fat and salt [34], whereas male students consume more grains [33]. Regardless of gender, grain was the food category with the highest average plate waste across all food groups [33]. Consequently, this investigation revealed that X Girls High School had a greater overall level of wastage than Y Senior High School. Rice and noodles were the second most wasted food group at both schools, with X Girls High School discarding more than Y Senior High School. Fruit was the food group that was wasted the least at X Girls High School and the most at Y Senior High School.

4.2. Factors of Lunch Food Waste

4.2.1. Meal Quality

All meals must be made by 11 a.m.; thus, the caterer frequently chooses side dishes with components that are not deteriorated by long-term storage. As a result, mung bean noodles and starch-processed foods have become popular dishes to prepare. All of these foods are filling since they are nearly equivalent to staple foods. Therefore, when these foods are included in a lunch combo, students are likely to reject one of them, resulting in further food waste. Falasconi et al. [5] observed that the existence of identical attribute items in the composition of Italian menus affected the amount of food consumed by students. Most teachers and students agreed that the taste and color of food should be enhanced to stimulate desire and increase eating motivation. Previous studies concluded that the sensory characteristics of the food had a significant effect on the dislike of school lunches among students [5,31]. In addition, meals are frequently served cold because they must be prepared an hour prior to being delivered to students on time, which also lowers the amount of food students consume. Boschini et al. [31] demonstrated that the external kitchen location influences the amount of unserved food because external providers may produce more food to compensate for any unintended losses that may occur during the transportation phase. Both school kitchens in this study are located within the school facilities, but the location of the kitchen and the delivery times also affect the quality of the meals.

“The taste is too greasy and salty, and the meal lacks freshness and color. Its appearance is thick and unpleasant.”

(A11)

“Some of the food is cold, but I prefer it warm. The meal will be delivered to the classroom in the fourth period and will be cold by then.”

(B14)

“The main reason is the low quality of the food. After switching caterers, the meal is getting worse and worse. Students only eat for the sake of eating; they don’t like it.”

(A07)

4.2.2. Rigid Budget Limitation

The contract fee for the caterer is based on the number of meals requested by the school and the cost of each meal. In Taiwan, the local government determines the expense of student lunches, which are either free or self-funded. During the past decade, Taiwan has been unable to achieve a consensus on lunch price increases that keep pace with inflation due to the absence of a school meal law and a different charging system. This has led to lunch budgetary constraints and a decline in meal quality. Additionally, affordability and nutrition are the guidelines for school lunches, which results in the majority of cases where meal budgets are not altered as the costs of ingredients and labor rise. In order to create more profit, caterers will reduce the quality and variety of meals, causing students to be less satisfied with their meals and generating more waste. This result was confirmed by Weng [14], who revealed that food service providers are hampered by tight budgets, which limits the range of lunch options and food alternatives.

“Inflation is currently affecting the global environment, and the costs of raw materials and labor are rising. Because the school hasn’t raised student meal prices in eight years, it’s becoming increasingly difficult to maintain the quality of the meals served, and suppliers are also under a lot of pressure.”

(B06)

“Schools adopt cost control to manage school lunches, and food safety, which was once a priority, is no anymore a concern for schools.”

(A03)

4.2.3. Tracking and Feedback System

Most caterers design meals based on their extensive experience. They lack a precise system for monitoring student feedback and the quantity and content of food thrown and consumed. It is necessary to provide canteens with the appropriate tools and methods to help them reduce food waste and report their progress [6]. In addition, they also lack a method for surveying students’ dietary preferences and exploring students’ unfamiliar and disliked foods. The absence of a tracking and feedback mechanism has prevented the catering company that has worked with the school for many years from reducing plate waste efficiently.

“We rarely communicate with the school and students. We don’t know how to improve because there are so few meetings with students to understand their needs, preferences, and opinions on food.”

(A01)

“Although the school has established a communication channel with students, the effect has been limited, since there has been little adjustment and no significant progress.”

(B04)

4.2.4. Unforeseen Factors

Even though the number of school meals is predetermined, factors such as student absenteeism, eating behavior during class, and the physical and mental health of the students still influence the actual number of meals that students consume. Notably, students’ eating habits during the mid-morning break affect their appetite at lunchtime. This finding was also supported by Boschini et al. [31]. Two sample schools have a school store where students can purchase food and snacks. Moreover, schools do not regulate or interfere with the snacks that students bring from home to school. These behaviors during breaks may significantly decrease students’ appetites for lunch. These unforeseen events may impede correct meal planning, resulting in the waste of all ingredients that have been prepared in advance or meals that have been provided. Malefors et al. [22] have shown that precisely forecasting attendance is the most efficient method for minimizing serving waste.

“The amount of food students eat at lunch will undoubtedly be impacted by how much they eat during physical education and break time.”

(A01)

“Whether the food is delicious or bad doesn’t really matter when it comes to the issue of food waste; rather, what matters more are the students’ emotions and physical health on the day of the meal.”

(A02)

“I eat less due to the stress of schoolwork, the ups and downs of life, or my exhaustion. I am sometimes unable to have lunch because of activities or tests.”

(A14)

4.2.5. Partial Eating Behavior

Partial eating was a common behavior among students, which had an impact on their meal selections and preferences. The majority of parents are more concerned about whether their children have eaten enough than the fact that they are picky eaters. Falasconi et al. [5] also discovered that many families do not care about their children’s dietary patterns. Some respondents said that parents who are supportive would prefer that schools eliminate partial eating behavior in their children through dietary education, but the sample schools do not seem to be taking further measures to change students’ unhealthy dietary behaviors. It is essential that schools improve their nutrition education and establish a connection between food waste and dietary habits.

“Of course, there are students who are picky, eating a lot of what they like and not even a bite of what they don’t.”

(A06)

“It is mostly due to the seriousness of picky eating, but a horrible meal will have an effect as well.”

(B03)

“In fact, some parents have no idea whether their children are picky eaters or what they do not like to eat. The positive parents would like to see the school improve the kids’ finicky eating habits, but they had no opinion or ideas regarding school food teaching.”

(B01)

4.2.6. Environmental Awareness

The catering service is a for-profit organization. Even though decreasing food waste can benefit operational efficiency, it may increase the expense of monitoring and investing more resources. Due to the higher expenses associated with implementing efforts to reduce food waste, caterers who lack an adequate understanding of environmental sustainability will be unable to implement such measures. Moreover, environmentally friendly attitudes and actions are seldom stressed in schools, resulting in students rarely reducing food waste on their own initiative. This illustrates the school leadership’s lack of attention and awareness of food waste. Therefore, prior research has underlined that fostering sustainable diet consciousness among schools, students, and caterers is the fundamental solution to school food waste [17,19,21]. The interaction between individuals’ food decisions and food, health, and the environment is referred to as sustainable diet consciousness, and it includes food skills, problem solving, information acquisition and sharing, individuals’ food attitudes and behaviors, animal welfare, and ecological sustainability [35].

“The restaurant handled the leftovers, which were unknown to the teachers. Regarding food waste education, the school has never taken the initiative to inform how to solve the problem, nor has it particularly notified teachers of any problems that necessitate their involvement.”

(A03)

“Although I have received knowledge in some areas, it is difficult for me to alter my behavior. I think that I require additional practice and supervision.”

(A09)

4.2.7. Lack of Initiatives for Reducing Food Waste

According to the interviews, most students understand how to avoid food waste, yet they continue to throw away food for a few reasons (e.g., bad taste, too many servings). It is vital for schools to establish explicit guidelines and policies to motivate students to reduce their food waste. There are strategies that can be implemented to reduce food waste in schools. For instance, schools might encourage students to bring lunchboxes that they can fill with the food they cannot finish or bring back uneaten fruit for afternoon consumption. Schools can also encourage students to share meals they do not enjoy eating in an effort to prevent food waste. Furthermore, schools can praise classes with the least amount of leftover food by organizing competitions. All of these approaches will assist students in reducing food waste by turning their knowledge into action. Izumi et al. [21] also recommended offering students meaningful incentives to contribute to solving the school lunch waste problem.

“I think it’s a waste to throw away something cooked in a restaurant that I can’t finish.”

(B10)

“If I can’t eat it, I’ll throw it away. Another reason is that even though I only took what I needed to eat, it was not as delicious as I had hoped, so I threw it away.”

(A12)

5. Discussion and Conclusions

In order to better understand the composition of student food waste in the two schools, this study investigates the level of school lunch waste in two high school kitchens in Taipei and measures the quantity of waste in each of the four food categories. Furthermore, on-site observations, as well as documentary and record analyses, were used to explore the reasons for the differences in food waste levels and composition between the two schools. This study also interviewed stakeholders to gain a better comprehension of the deeper factors that contribute to food catering service waste, in order to build more efficient means of minimizing food waste. By combining quantitative data with qualitative observations and interviews, the study provides more solid and reliable conclusions and strategies. In general, the inefficiency index of all items served at Y Senior High School under the same lunch caterer is lower than at X Girls High School. This implies that Y Senior High School students consumed more school lunches. There are several factors that contribute to the large differences in food consumption efficiency. First, disparities between the sexes in eating habits and food choices. Kuo and Shih [33] and Nozue et al. [36] identified the association between gender and school lunch consumption and waste. Nozue et al. [36] observed that in Japanese primary schools, boys were more likely than girls to select staple meals in addition to main dishes and/or side dishes. Kuo and Shih [33] further indicated that the average plate waste of females was more than that of males in the university dining hall. Second, the two schools have different requirements for over-preparation. X Girls High School requires school lunch caterers to offer excessive meals in response to students who may need to eat more. If the students do not need these surplus servings, those meals will be a serious source of food wastage. According to Falasconi et al. [5], the non-served food may be the result of the requirement to accommodate requests for additional portions and to facilitate portioning. This requirement may also be the consequence of the school’s failure to provide precise meal estimates [22]. If the students do not require these additional meals, it will be a significant cause of non-served food waste. Third, the two institutions have diverse recycling practices. X Girls High School has a fruit recycling box in the canteen, encouraging students to recycle fruits that have not been eaten and have not been cut (such as bananas and oranges), resulting in a high fruit consumption rate at X Girls High School. In contrast, Y Senior High School encourages students to share meals they do not enjoy eating during lunchtime in an effort to prevent food waste, resulting in a high food consumption rate at Y Senior High School.

Additionally, in order to better understand the causes influencing food catering service waste, this study identifies seven factors related to school lunch waste based on interview data and suggests five waste reduction strategies to address these problems. The first step is to enhance the quality of the meals. Everyone appreciates tasty and hot food. As humans are visual beings, food that appears appealing often stimulates our appetite. In addition, food service providers must pay attention to the menu’s composition to avoid pairing similar items, such as rice and starches. This finding is also supported by previous research [5,23] indicating that the choice of recipes can have a significant impact on food waste, and unpopular meals can increase consumer leftovers. Thus, the quality of the meals and the recipes used may have a considerable impact on students’ appetites for lunch. Second, budget typically plays a significant role in determining the quality of school meals; however, the budget for school meals does not increase as the cost of ingredients and labor rises. Consequently, it is suggested that the government establish meal budget guidelines based on the cost of goods. Thus, food service providers may maintain school lunch quality within a reasonable budget. School meals are served by public catering establishments in several European countries [22,26]; however, in Taiwan, a hybrid system of public and private catering establishments is used. As a result, budgetary constraints are discussed less frequently in research papers. Third, the catering firm must implement a tracking and feedback system that collects frequent and long-term data on the quantity and composition of leftovers among students. The caterer must also communicate with students to understand their dietary preferences and specifications. In this method, the caterer can offer adequate portions and meals that meet the desires of the students to improve their appetite. Next, for caterers, the greatest difficulty in meal preparation is the presence of unforeseeable events. This study revealed unpredictability in student absenteeism, eating behavior during the mid-morning break, and the student’s emotional and physical health. It is possible to raise the predictability of lunch attendance and influence dietary practices during breaks through school policies. Schools can attempt weekly estimates of the number of students for the upcoming week, enabling caterers to take this into account while planning menus and procuring the necessary materials. Moreover, schools should also advise students to prevent excessive eating during mid-morning recesses so that hunger levels and the amount of food consumed at lunchtime are not affected. Prior research has also demonstrated that accurately estimating attendance and regulating students’ diets during class can successfully reduce waste and raise students’ appetite [22,31]. Finally, sustainable diet education and initiatives are the core solutions to the issue of food waste among students. According to the findings of this study, sustainable diet education in schools should emphasize healthy eating behaviors and the connection between diet, the environment, and society. Moreover, incentives must be reinforced to motivate students to take proactive measures to prevent food waste. Prior research has revealed, however, that the most significant barrier to adopting sustainability education in schools is a lack of awareness and comprehension of food waste issues among school administrators, which hinders schools’ ability to progress towards a sustainable educational institution [17]. This has resulted in the unusual adoption of food waste reduction practices in school canteens, even by institutions claiming to be committed to sustainability [17]. Sustainable diet education should not be limited to food waste but extend to environmental and social dimensions, such as managing human nutrition systems; reducing food insecurity; ensuring access to healthy, nutritious, and sustainable food for all living things; reducing environmental impacts and the loss of biodiversity; and mitigating climate change [30]. On this basis, a sustainable food system that is equitable, healthful, and environmentally friendly can be developed.

The findings of this study provide a better understanding of the food waste problem among Taiwanese high school students who participate in the school lunch program, and the proposed strategies improve the management of contracted catering companies in schools, thereby reducing school lunch waste from supply sources. This research reveals that the food inefficiency index in the two sample schools ranged from 14% to 25%, with rice and noodles being the most wasted categories of food. The explanations for the discrepancy included school rules, recycling regulations, and gender. Furthermore, we interviewed stakeholders to identify seven key factors influencing student food waste. Prior studies have investigated school lunch waste and proposed waste reduction strategies in various countries [5,17,22], but tracking and feedback systems and budgetary restrictions have received less attention. Moreover, previous studies have primarily focused on countries with free lunches; therefore, this topic has not been extensively discussed. Taiwan’s experience can provide solid evidence for this topic, serves as a model for countries in comparable situations, and academically fills in gaps in the experiences of varied societies.

6. Limitation

This study still has some research limitations. Since it is difficult to remove bones and peels from many Taiwanese foods that are attached to the flesh and bones or the skin (such as spareribs and papaya), bones and peels are included in the measurement. Accordingly, the statistics for main dishes and fruits are overestimated compared to the actual amount of waste. The precision of the measurement still requires improvement. Therefore, it is recommended that future research exclude unavoidable food waste (such as bones and peels) during the measurement to determine the real amount of food consumed and wasted by students. As study samples, only two high schools in Taipei with independent kitchens managed by a contracted catering company were explored. As an exploratory case study, this research can offer an understanding of the topic as a possible underpinning for further research. As case studies, however, additional discussion of other catering companies and institutions is required for the development of knowledge. Future studies are proposed to extend the number of schools served by different catering firms in Taiwan as case studies, in order to gain a more complete understanding of Taiwan’s high school lunch waste and to validate its external validity.