Research

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16 pages, 2076 KiB

Open AccessArticle

Dynamic Changes in Physicochemical and Microbiological Qualities of Coconut Water during Postharvest Storage under Different Conditions

by Rachatida Detudom, Pawinee Deetae, Hu Wei, Hu Boran, Shiguo Chen, Sirithon Siriamornpun and Cheunjit Prakitchaiwattana

Horticulturae 2023, 9(12), 1284; https://doi.org/10.3390/horticulturae9121284 - 29 Nov 2023

Cited by 1 | Viewed by 1423

Abstract

Coconut is naturally sealed with coconut water inside. Microbial contamination occurs only after the seal is broken during extraction. This study evaluated changes in the microbiological, physicochemical, and chemical properties of coconut water during postharvest storage at ambient and refrigerated temperatures. Initial microbial [...] Read more.

Coconut is naturally sealed with coconut water inside. Microbial contamination occurs only after the seal is broken during extraction. This study evaluated changes in the microbiological, physicochemical, and chemical properties of coconut water during postharvest storage at ambient and refrigerated temperatures. Initial microbial counts ranged from 2 to 5 log CFU/mL, while physicochemical factors, including total soluble solids (TSSs), pH, and sugar content (4–7 °Brix, 5.0–5.5, 4–6% g/100 mL), were consistent. The dynamic changes in the physicochemical properties of coconut water stored under both conditions exhibited a clear correlation with the increased microbial populations. Fructose was the primary sugar, with citric and malic acids as major acids, while the predominant volatile compounds were ethanol, ethyl acetate, ethyl ester, acetic acid and octanoic acid. Storage conditions led to similar microbial and physicochemical changes, but ambient temperature accelerated spoilage 10 times faster than refrigeration. Sucrose decreased steadily, whereas fructose and glucose remained stable until a precipitous decline coincided with lactic acid bacteria (LAB) reaching >6 log CFU/mL on the final day of storage. Weissella cibaria and Leuconostoc spp. are the main species in coconut water. The presence of specific volatile compounds, including octanoic acid, acetic acid, ethyl acetate, and butyl phenol, is associated with the activities of Lactobacillus, particularly Weissella. There was a clear relationship among microbial groups and populations, total titratable acidity (TTA), and sensory criteria. Remarkably, TTA was closely correlated with total plate count (TPC) (>5 log CFU/mL) and an unacceptable sensory rating. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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15 pages, 2063 KiB

Open AccessArticle

Identification and Analysis of Reference and Tissue-Specific Genes in Bitter Gourd Based on Transcriptome Data

by Yangyi Zheng, Yao Ma, Jianning Luo, Junxing Li, Xiaoming Zheng, Hao Gong, Liting Deng, Gangjun Zhao, Caixia Luo, Xiaoxi Liu and Haibin Wu

Horticulturae 2023, 9(12), 1262; https://doi.org/10.3390/horticulturae9121262 - 24 Nov 2023

Viewed by 778

Abstract

Accurate and standardized quantification of reverse transcription PCR (qRT-PCR) results relies on the use of a dependable reference gene. The precise control of transgene expression in terms of both spatial and temporal aspects necessitates the utilization of tissue-specific gene promoters. However, the identification [...] Read more.

Accurate and standardized quantification of reverse transcription PCR (qRT-PCR) results relies on the use of a dependable reference gene. The precise control of transgene expression in terms of both spatial and temporal aspects necessitates the utilization of tissue-specific gene promoters. However, the identification of stable reference genes across various tissues, particularly in fruits at different ripening stages, as well as tissue-specific genes in bitter gourds, remains largely unexplored. In this study, we employed RNA-Seq-based transcriptome datasets obtained from nine tissues to comprehensively screen for new reference genes (NRGs) and tissue-specific genes. Through the utilization of five algorithms in conjunction with qRT-PCR analysis, we successfully identified two highly stable reference genes, namely HMG1/2 and PHOS32, from a pool of 11 NRGs and five traditional reference genes (TRGs). To validate their reliability, we performed expression pattern analysis of two genes associated with fruit ripening (McACO1 and McACO2) using HMG1/2 and PHOS32, as well as an unstable reference gene, HSCP2. Furthermore, we conducted qRT-PCR validation of 12 tissue-specific genes using HMG1/2 as the reference gene. This study not only contributes to the precise normalization of target genes in bitter gourd but also provides a solid foundation for regulating transgenes through the utilization of suitable tissue-specific promoters. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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14 pages, 1057 KiB

Open AccessArticle

Effect of Processing Methods on the Postharvest Quality of Cape Gooseberry (Physalis peruviana L.)

by Sara Agudelo-Sánchez, Yadiela Mosquera-Palacios, Dairon David-Úsuga, Susana Cartagena-Montoya and Yudy Duarte-Correa

Horticulturae 2023, 9(10), 1158; https://doi.org/10.3390/horticulturae9101158 - 22 Oct 2023

Viewed by 1460

Abstract

The cape gooseberry (Physalis peruviana L.) is an exotic tropical fruit of great national and international importance due to its nutritional and organoleptic properties. The objective of this study was to evaluate different postharvest treatments—coating, vacuum impregnation, and immersion—on the conservation of [...] Read more.

The cape gooseberry (Physalis peruviana L.) is an exotic tropical fruit of great national and international importance due to its nutritional and organoleptic properties. The objective of this study was to evaluate different postharvest treatments—coating, vacuum impregnation, and immersion—on the conservation of several quality characteristics of cape gooseberry fruit. Moreover, the different conditions of the selected treatments were studied. Weight loss was assessed with a gravimetric analysis of the fresh and treated fruit. Firmness was determined by the instrumental texture. A sensory analysis was conducted using a multidimensional profile approach. Of the treatments evaluated, the lowest weight loss was recorded with the use of coating and immersion. However, the immersion process resulted in the product with the highest overall quality according to the sensory analysis and presented the most appropriate texture according to the firmness values. Finally, in the evaluation of the immersion, a significant influence of the CaCl₂ immersion time (p < 0.05) on the firmness values of the product was found, resulting in longer times leading to less firm products. Considering 10% as a commercial standard limit for weight loss, the fruit treated under immersion and coating processes can be stored for at least 12 days. The immersion process is highlighted because it improved the sensory characteristics with respect to the control (i.e., without treatment). Therefore, it is a promising alternative for the postharvest treatment of cape gooseberries. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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16 pages, 2975 KiB

Open AccessArticle

Effect of Preharvest Ethephon Application on Selected Biochemical Components and Polyphenol Oxidase Activity in Macadamia Nuts

by Noluthando Noxolo Aruwajoye, Asanda Mditshwa, Lembe Samukelo Magwaza, Mjabuliseni Simon Cloapas Ngidi and Samson Zeray Tesfay

Horticulturae 2023, 9(10), 1101; https://doi.org/10.3390/horticulturae9101101 - 04 Oct 2023

Viewed by 1295

Abstract

Ethephon is a plant growth regulator that triggers diverse responses in plants, such as fruit ripening, leaf senescence, hull senescence, stem elongation, and nut abscission. This study examined how the preharvest application of ethephon 480 SL^® affects selected biochemical components and polyphenol [...] Read more.

Ethephon is a plant growth regulator that triggers diverse responses in plants, such as fruit ripening, leaf senescence, hull senescence, stem elongation, and nut abscission. This study examined how the preharvest application of ethephon 480 SL^® affects selected biochemical components and polyphenol oxidase (PPO) activity in two macadamia nut cultivars: ‘788’ and ‘Beaumont’. Ethephon was applied to the trees via a Cima mist blower at rates of 13.33 mL/L per hectare for the ‘788’ cultivar and 16.67 mL/L per hectare for the ‘Beaumont’. Following harvest, the nuts were stored at 25 °C for 72 days, and samples were taken at 18-day intervals. Standard procedures were used to assess the following: total phenolics, total flavonoids, 2,2,-diphenyl-1-picrylhydrazyl (DPPH) assay, Ferric reducing ability power (FRAP) assay, sucrose, total protein, and PPO activities. This evaluation was carried out across a total of four treatments: ethephon-treated nuts from the orchard floor (ED), ethephon-treated nuts from the tree (ET), untreated nuts from the orchard floor (CD), and untreated nuts from the tree (CT). The evaluation’s outcomes were analyzed using a principal component analysis (PCA), a correlation matrix heat map (CMHM), and a graphical assessment. The results unveiled significant correlations and associations among the assessed parameters. The correlation matrix heat map analysis highlighted a strong positive correlation (0.97) between the sucrose and the PPO activity in the ‘Beaumont’ cultivar, supported by the PCA analysis identifying the ED treatment as the most influential. At the storage period’s conclusion, the ED treatment had the highest sucrose content (18.63 mg/g) and polyphenol oxidase activity (1.06 U g⁻¹). In the ‘788’ cultivar, a close relationship emerged between the phenolic content, the PPO activity, and the Ferric reducing antioxidant power (FRAP)’s antioxidant activity. Consistently, the CT treatment (untreated nuts) demonstrated positive correlations with several key parameters in both cultivars, displaying heightened phenolic content and antioxidant activities. Consequently, our findings indicate that the CT treatment, involving tree-harvested nuts without ethephon application, could be the preferred option for sustaining macadamia nuts’ quality and shelf life compared to other methods. Moreover, our study underscores the significance of proper storage conditions for maintaining the desired biochemical parameters of macadamia nuts. By comprehending the effects of distinct treatments and harvesting techniques, producers and processors can devise strategies to optimize storage conditions and uphold macadamia nut quality. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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21 pages, 2059 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Effects of UV-C Irradiation and Low Temperature Treatment on Microbial Growth and Oxidative Damage in Fresh-Cut Bitter Gourd (Momordica charantia L.)

by John Louie Baligad, Pung-Ling Huang and Yi-Yin Do

Horticulturae 2023, 9(10), 1068; https://doi.org/10.3390/horticulturae9101068 - 23 Sep 2023

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Abstract

Fresh-cut fruits and vegetables are convenient and retain maximum nutrients. However, even minimal processing accelerates product deterioration and reduces food safety due to microbial infection. In this study, the effects of UV-C irradiation, low temperature treatment, and their combination on the microbial risk [...] Read more.

Fresh-cut fruits and vegetables are convenient and retain maximum nutrients. However, even minimal processing accelerates product deterioration and reduces food safety due to microbial infection. In this study, the effects of UV-C irradiation, low temperature treatment, and their combination on the microbial risk of fresh-cut bitter gourd were evaluated. Firstly, next-generation sequencing technology was utilized to identify microorganisms on the surface of fresh-cut bitter gourd after 12 h of exposure to room temperature, and a total of 34 bacterial species were identified. Subsequently, fresh-cut bitter gourd treated with UV-C or/and 4 °C and then kept at room temperature for 6 h was assessed for its viable bacterial count. The results showed that both 0.5 and 1.5 kJ·m⁻² UV-C irradiation significantly inhibited microbial growth compared to 4 °C and the no treatment control. Meanwhile, no significant differences were observed between UV-C and the combined treatments. Lower doses of UV-C irradiation reduced hydrogen peroxide and malondialdehyde content, increased the proline level, and improved the activities of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, catalase, and critical enzymes involved in the phenylpropanoid pathway, such as phenylalanine ammonia-lyase and polyphenol oxidase. This suggests that UV-C irradiation alone can effectively reduce bacterial contamination in fresh-cut bitter gourd to an acceptable level. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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15 pages, 3816 KiB

Open AccessArticle

Cut-Wounding Promotes Phenolic Accumulation in Cucumis melo L. Fruit (cv. Yugu) by Regulating Sucrose Metabolism

by Yuanyuan Guo, Zhifang Yu, Ruxin Li, Libin Wang, Chunyan Xie and Zhangfei Wu

Horticulturae 2023, 9(2), 258; https://doi.org/10.3390/horticulturae9020258 - 15 Feb 2023

Viewed by 1270

Abstract

The effect of cutting on the molecular changes underlying sucrose metabolism and the phenylpropanoid pathway in melon fruit (cv. Yugu) during storage at 15 °C was investigated. Furthermore, the key metabolites, enzymes, and genes involved in sucrose and phenylpropanoid metabolism were determined. Results [...] Read more.

The effect of cutting on the molecular changes underlying sucrose metabolism and the phenylpropanoid pathway in melon fruit (cv. Yugu) during storage at 15 °C was investigated. Furthermore, the key metabolites, enzymes, and genes involved in sucrose and phenylpropanoid metabolism were determined. Results showed that the cutting of melon increased the activities of acid invertase (AI), neutral invertase (NI), and sucrose synthase-cleavage (SS-c) and the expressions of CmAI1/2, CmNI1/2, and CmSS1, while sucrose synthase-synthesis (SS-s) and sucrose phosphate synthase (SPS) activities and the CmSS2/3 and CmSPS1/2/4 gene expressions were suppressed. These led to sucrose decomposition and fructose and glucose accumulation in fresh-cut melon at the early stage of storage. Moreover, cutting increased the activity and gene expression of hexokinase, which accelerated the transformation of hexose in fresh-cut melon. In addition, cutting enhanced the activities of phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL) and up-regulated the expressions of CmPAL1-9, CmC4H1-4, and Cm4CL1/2/3, which activated phenylpropanoid metabolism and resulted in phenolic accumulation in fresh-cut melon. These findings demonstrate that cutting of melon can enhance sucrose metabolism and phenylpropanoid pathway by regulating the activities and gene expressions of related enzymes. Therefore, cut-wounding promoted the conversion of sugars to supply the necessary substrates for phenolic accumulation in fresh-cut melon. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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14 pages, 2022 KiB

Open AccessArticle

Effects of Forced-Air Precooling on Postharvest Physiological and Storage Quality of Winged Beans

by Ying-Che Lee, Min-Chi Hsu, Jia-Zhu Liao, Zhao-Wei Wei, Hsin-Ying Chung and Yu-Shen Liang

Horticulturae 2023, 9(1), 45; https://doi.org/10.3390/horticulturae9010045 - 02 Jan 2023

Cited by 1 | Viewed by 1912

Abstract

Winged beans accumulate abundant field heat following harvest, and their shelf life is shortened if precooling is not performed promptly. In the present study, top-suction forced-air precooling (FC) was employed to rapidly remove field heat from pods, and its effects on winged bean [...] Read more.

Winged beans accumulate abundant field heat following harvest, and their shelf life is shortened if precooling is not performed promptly. In the present study, top-suction forced-air precooling (FC) was employed to rapidly remove field heat from pods, and its effects on winged bean pod storage quality and shelf life were assessed. After postharvest FC to remove field heat from winged bean pods, the mean 1/2 precooling time was 5.8 min and 7/8 precooling time was 14.7 min, which was 9.6 times and 11.7 times faster than room cooling (RC), respectively. Moreover, after FC was applied to remove field heat, the weight loss rate at 7/8 precooling time was 0.92%, significantly lower than that after RC was applied (1.98%). FC could delay decay, and the decay rate was only 18% on day 14 storage, which was lower than 52% of RC. During 12 °C and 85% relative humidity (RH) storage, the shelf life of winged bean pods in the FC group was 14.8 days, which was significantly longer than that of the pods in the RC group (10.6 days). In conclusion, FC is an effective precooling method to rapidly remove field heat postharvest and maintain the storage quality of winged beans. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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Review

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23 pages, 1586 KiB

Open AccessEditor’s ChoiceReview

Advances in Postharvest Diseases Management of Fruits and Vegetables: A Review

by Farid Moradinezhad and Azam Ranjbar

Horticulturae 2023, 9(10), 1099; https://doi.org/10.3390/horticulturae9101099 - 04 Oct 2023

Cited by 2 | Viewed by 2801

Abstract

Sustainable agriculture requires factors to directly stimulate plant growth and induce the plant’s innate immune system to protect against stresses. Protection of plants is one of the main approaches to the supply of food resource. Furthermore, improved techniques for plant disease management must [...] Read more.

Sustainable agriculture requires factors to directly stimulate plant growth and induce the plant’s innate immune system to protect against stresses. Protection of plants is one of the main approaches to the supply of food resource. Furthermore, improved techniques for plant disease management must be environmentally sustainable, reliable, acceptable by society, and chemical-free to ensure sustainable food security. Although it is not possible to accurately determine postharvest losses due to diseases and physiological disorders, the use of proper harvesting and transportation methods that minimize damage to the product, along with optimal storage conditions that prevent the development of diseases, will be effective in reducing these postharvest losses. Since handling and storage conditions are potential threats for postharvest spoilage, it is necessary to identify environmentally friendly approaches and their precision mechanisms for postharvest disease management. Recently, biological control, non-chemical, and eco-friendly techniques have been investigated for this purpose. Full article

(This article belongs to the Special Issue Postharvest Biology and Molecular Research of Horticulture Crops)

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