Physiological and biochemical responses of grapefruit seed extract dip on ‘Redglobe’ grape

Table grapes (Vitis vinifera cv. Redglobe) were immersed in 1 g L⁻¹ grapefruit seed extract (GSE) for 60 s at 15 °C and then stored at 2 ± 1 °C, and the related physiological effects were investigated. The results showed that GSE treatment lowered the respiration rate and ethylene evolution in the whole cluster. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) were increased and extended by GSE treatment, however, polyphenol oxidase (PPO) activity was suppressed. Furthermore, increase of malondialdehyde (MDA) as well as membrane permeability was delayed in GSE-treated grapes. Total phenolic compounds degradation was substantially lower in GSE-treated grapes than in control. The soluble solids content (SSC) in GSE-treated grapes was always higher than in control, although there was no significant difference at the level of P < 0.05. Our study suggests that GSE might be a promising candidate for extending the postharvest storage time of table grapes.     

Physical properties of a barley protein/nano‐clay composite film containing grapefruit seed extract and antimicrobial benefits for packaging of Agaricus bisporus

Barley protein (BP) was extracted from barley flour, and a BP film was prepared. To improve the physical properties of the BP film, nano‐clay was incorporated. Among the films prepared, the composite film containing 4% BP/1% Cloisite Na⁺ had the best physical property. The composite film containing grapefruit seed extract (GSE) was prepared and used as a packaging film for the button mushroom. Packing of the mushroom with this film inhibited microbial growth during storage. After 7 days of storage, packaging of mushrooms with the film containing 0.7% GSE reduced the populations of total aerobic bacteria and yeast and moulds by 0.95 and 0.58 log CFU/g, respectively, compared with the control. These results suggest that the BP/Cloisite Na⁺ film containing GSE can be used as an environment‐friendly packaging for maintaining mushroom quality during storage.     

Effects of exogenous 24‐epibrassinolide to control grey mould and maintain postharvest quality of table grapes

The potential of various concentrations of 24‐epibrassinolide (EBR) treatments on the control of grey mould in artificial Botrytis cinerea inoculation test and on the maintenance of postharvest quality of table grapes without inoculation in cold storage were researched. In the cold storage, clusters of grapes with exogenous EBR application (EBR1, 0.1 mg L^?1 EBR; EBR2, 0.4 mg L^?1 EBR; EBR3, 0.8 mg L^?1 EBR) were stored at 0 ± 1 °C. Fruits’ quality attributes including berry firmness, weight loss, berry drop, decay berry percentages, total sugar and titratable acidity were measured at 15, 30 and 60 days. The results showed that EBR treatments exhibited a higher berry firmness and a lower percentage of weight loss, berry drop and decay berry. In the artificial inoculation trial, single berries were immersed in EBR1, EBR2 and EBR3, then inoculated by spraying with a B. cinerea spore suspension and stored at 25 ± 2 °C and 95% relative humidity. Disease severity (DS), lipid peroxidation and defence‐related enzymes of these berries were analysed every 2 days. EBR‐treated berries resulted in an increase in activities of defence‐related enzymes including superoxide dismutase, peroxidase, catalase and phenylalanine ammonia‐lyase compared with control berries inoculated by B. cinerea. Simultaneously, significant decreases in DS and production of superoxide anion radical and malondialdehyde were observed. These results suggested that exogenous application of EBR could play a protective role in controlling the grey mould of postharvest grapes and maintaining the postharvest quality during cold storage.     

Reduction of Fluid Loss from Grapefruit Segments with Wax Microemulsion Coatings

Fresh whole peeled grapefruit or segments produced by vacuum infusion with pectinases are considered minimally processed products. When dry packed, segments from mature late season fruit had fluid losses >15% during 4 wk storage. Edible wax microemulsion coatings reduced leakage of dry-packed segments by 80% after 2 wk, and 64% after 4 wk storage, and were optimally effective in reducing leakage when diluted to 12% solids. Coatings could be made with polyethylene, candelilla or carnauba wax, and with lauric, stearic, palmitic, oleic or myristic acids. Coatings with carnauba wax were most effective. Whether made with morpholine or ammonia as the base, coatings were not detected by informal taste panels before or after storage.     

Effect of thermal treatment and storage on the stability of organic acids and the functional value of grapefruit juice

The effect of conventional and microwave pasteurisation on the main bioactive compounds of grapefruit juice and their stability during 2 months’ refrigerated and frozen storage was evaluated. Ascorbic acid (AA), vitamin C and organic acids were analysed by HPLC, whereas total phenols and antioxidant capacity (%DPPH) were measured by spectrophotometry. The results showed that conventional treatment led to a significant decrease in citric acid (from 1538 to 1478 mg/100 g) and AA (from 36 to 34.3 mg/100 g), whilst microwave pasteurisation preserved these compounds. Frozen storage maintained AA and vitamin C, especially in treated samples. Frozen non-treated samples and conventional pasteurised ones preserved about a 75% and 20% of the total phenols and antioxidant capacity, respectively, whilst in frozen microwave pasteurised juices this preservation was of 82% and 33%. From these results, the use of microwave energy may be proposed as an alternative to traditional heat pasteurisation in order to preserve the natural organoleptic characteristics and essential thermolabile nutrients of grapefruit juice.     

Effect of rapeseed protein–gelatin film containing grapefruit seed extract on ‘Maehyang’ strawberry quality

To develop a packaging film for ‘Maehyang’ strawberries, an edible film containing antimicrobial grapefruit seed extract (GSE) was manufactured. Addition of GSE to the rapeseed protein–gelatin (RG) film inhibited the growth of pathogenic bacteria such as Escherichia coli O157:H7 and Listeria monocytogenes. Packaging of ‘Maehyang’ strawberries with the RG film containing 1.0% GSE decreased the populations of total aerobic bacteria and of yeast and moulds in the strawberries by 1.03 and 1.34 log CFU g^?1, respectively, after 14 days of storage, compared to that of the control. Sensory evaluation of the GSE‐RG film‐packaged strawberries produced better sensory scores than did the control. These results suggest that RG film containing GSE can be used to package strawberries and to extend shelf life.     

Thermosonication: a potential technique that influences the quality of grapefruit juice

Thermosonication (TS) is an emerging nonthermal processing technique used for the liquid food preservation and is employed to improve the quality and acceptability of grapefruit juice. In this study, fresh grapefruit juice samples were subjected to TS treatment in an ultrasonic cleaner with different processing variables, including temperature (20, 30, 40, 50 and 60 °C), frequency (28 kHz), power (70%, 420 W) and processing time (30 and 60 min) for bioactive compounds, inactivation of enzymes pectin methylesterase (PME), peroxidase (POD) and polyphenolase (PPO) and micro‐organisms (total plate count, yeasts and moulds). The micro‐organism activity was completely inactivated in the treatment (60 °C for 60 min). The TS treatment at 60 °C for 60 min exposure reduced PME, PPO and POD activity by 91%, 90% and 89%, respectively. Results indicate that the advantages of TS for grapefruit juice processing at low temperature could enhance the inactivation of enzymes and micro‐organisms and it can be used as a potential technique to obtain better results as compared to alone .     

The effects of composite coatings containing chitosan and Mentha (piperita L. or x villosa Huds) essential oil on postharvest mold occurrence and quality of table grape cv. Isabella

The effects of coatings containing shrimp chitosan and the essential oil from Mentha piperita L. (MPEO) or M. villosa Huds (MVEO) to control common mold infections in table grape cv. Isabella (Vitis labrusca L.) that were caused by Aspergillus niger, Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer were evaluated. The effects of the coatings on physicochemical and sensory characteristics of the grapes were also assessed. The coatings containing chitosan (4, 8 mg/mL) and MPEO or MVEO (1.25, 2.5, 5 μL/mL) delayed the mold growth and reduced the incidence of infections caused by all test fungi in grapes during storage at room and low temperatures. The coatings (chitosan 4 mg/mL; MPEO or MVEO 1.25, 2.5 μL/mL) did not negatively affect the physicochemical and sensory characteristics of grapes. From these results, coatings containing chitosan and MPEO or MVEO are potential postharvest treatments to control common mold infections in table grape cv. Isabella.Industrial relevanceIn table grapes, the reduction of losses resulting from fungal rot is a major goal of postharvest technology, which seeks to use effective methods to control the contamination and the growth of phytopathogenic fungi. However, the negative consumer perception of synthetic fungicides used for many years to solve the problem of mold infections in table grapes and the development of fungicide-resistant strains have impelled researchers to study the efficacy of natural compounds against postharvest pathogenic fungi. In this context, edible coatings composed of chitosan and essential oils have been considered as an environmentally friendly and added-value technology to control fungal postharvest decay in table grapes because of their biodegradability and lack of phytotoxicity. In this study, the authors evaluated composite coatings that contained shrimp chitosan and reduced amounts of Mentha (piperita L. or x vilosa Huds) essential oil as postharvest treatment to control the occurrence of mold infections caused by fungi in table grape cv. Isabella (Vitis labrusca L.), and their effects on the quality attributes of this fruit during storage. The tested composite coatings are presented as possible alternative technologies to control fungal infections and related post-harvest losses in table grape cv. Isabella.     

葡萄柚籽提取物对延边黄牛肉保鲜效果的影响

通过测定不同质量分数(0.05％、0.10％、0.15％)葡萄柚籽提取物(GSE)处理的延边黄牛肉在保鲜期内的感官指标、理化指标及微生物指标,研究葡萄柚籽提取物对延边黄牛肉保鲜效果的影响.结果表明:葡萄柚籽提取物对延边黄牛肉有较好的保鲜效果,实验组和对照组相比,延边黄牛肉的保鲜期延长了2～4d,且质量分数为0.10％GSE处理的肉样保鲜效果最好.     

Antibacterial Effect of Grapefruit Seed Extract (GSE) on Makgeolli‐Brewing Microorganisms and Its Application in the Preservation of Fresh Makgeolli

To develop a new preservation method, the antimicrobial activity of grapefruit seed extract (GSE) against Makgeolli‐brewing microorganisms and food‐borne pathogens was assessed, and a general analysis and sensory evaluation of fresh Makgeolli with added GSE was made. The minimum inhibitory concentration (MIC) values of GSE against 10 strains of Makgeolli‐brewing microorganism were 0.0122 to 1.5625 μL/mL. The MIC values against 6 strains of food‐borne pathogens were 0.0061 to 0.7813 μL/mL. On addition of 0.1% (v/v) and 0.2% GSE in bottled fresh Makgeolli, no significant difference in the pH, or the contents of total acids, ethanol, or methanol in the Makgeolli, were observed compared with control Makgeolli (with no GSE), during the preservation period (8 weeks) at 10 °C. In the Makgeolli with 0.1% and 0.2% GSE, the total bacterial counts decreased significantly by 4.9% (P < 0.01) and 11.2% (P < 0.001), respectively, versus the control. The decreases in yeast count were significantly lessened by 15.33% and 15.24% (both P < 0.001), respectively, after 8 weeks of storage, compared with the control. In the sensory evaluation of Makgeolli with 0.1% and 0.2% GSE, the refreshment and overall acceptability received significantly better scores than the control (P < 0.01), with no change in sweetness, bitterness, sourness, turbidity, color, or odor. These results suggest that GSE controls the growth of Makgeolli‐brewing microorganisms and extends the shelf life (ca. 2 wk), without decreasing overall acceptance.     

A potential of ultrasound on minerals,micro‐organisms,phenolic compounds and colouring pigments of grapefruit juice

The grapefruit juice was sonicated in an ultrasonic bath at 28 kHz frequency (amplitude 70%), for 0, 30, 60 and 90 min at 20 °C. This research was focused on the effects of ultrasound treatment on phenolic compounds, minerals, viscosity, lycopene, total anthocyanins, total carotenoids, micro‐organism analysis and sugars. A statistically significant increase was observed in total carotenoids, lycopene, sugar contents (sucrose, glucose and fructose) and phenolic compounds, whereas a decrease in viscosity and micro‐organisms were found in all the grapefruit juice samples sonicated for 30, 60 and 90 min as compared to control. However, maximum improvement was observed in the sonication treatment for 90 min. The results of this study suggest that ultrasound treatment may improve the quality of grapefruit juice.     

Quality response of table grapes (Vitis vinifera L.) during cold storage to postharvest cap stem excision and hot water treatments

Berry quality, total phenol, sensory characteristics and decay incidence of grapes (V. vinifera cvs. Mü?küle and Red Globe) as affected by prestorage hot water immersion with or without cap stem excision treatments were investigated with 7‐day interval during storage at 1 °C for 21 days. Weight loss occurred mainly up to the second week and was more pronounced for the untreated control samples subjected to the stem excision. In Mü?küle, the least weight loss value was obtained from hot water–treated grapes (0.62%), while the highest loss occurred in control grapes of stem‐excised berries (0.96%). Immersion of stem‐retained grapes in hot water was the best applications for maintenance of overall storage quality for both cultivars. According to panellist scores, it is evident that hot water has positive effect on maintaining the minimally processed table grapes without altering the flavour and taste of the commodity. Stem‐retained berries of hot water treatment had the highest score for both Mü?küle and Red Globe, with their values 3.8 and 4.2, respectively, while the least values were obtained from stem‐excised berries of untreated control group of both the cultivars (1.9 and 3.0, respectively). At the end of three‐week storage, the least decay rates were determined in stem‐retained berries that received hot water treatment (5.3% for Mü?küle and 1.1% for Red Globe). Attenuate influence of brief high temperature exposure on ripening parameters (SSC, TA, MI, pH) was also observed. Postharvest hot water treatment may be used as a nonchemical means to extent storage life of minimally processed grapes with its alleviating effect on physiological disorders. Cap stem retaining in minimal processing can be recommended to maintain the quality of grapes.     

Immobilization of naringinase on asymmetric organic membranes: Application for debittering of grapefruit juice

An enzymatic membrane reactor (EMR) is assembled for the immobilization of naringinase on a polyethersulfone ultrafiltration membrane, based on fouling-induced method. The effects of molecular weight cut-off, membrane configuration, applied pressure, enzyme concentration and pH are studied in terms of permeate rate, immobilization efficiency, and biocatalytic conversion. The 10 kDa membrane operating in reverse mode, 0.2 MPa, 0.3 gL⁻¹ of enzyme in acetate buffer at pH 5 and cross-linking with 0.25% glutaraldehyde showed the highest naringin conversion (73%). It was determined that the intermediate pore blocking model was the predominant fouling mechanism for the enzymatic immobilization. The EMR was applied for debittering of grapefruit juice, achieving a conversion of naringin below bitterness threshold and maintaining the antioxidant capacity of the juice. Furthermore, the biocatalytic activity of immobilized enzyme was retained at a high level at least during three consecutive reaction runs, with overnight storage at 4 °C after each run.Industrial relevanceThe potential of membrane technologies in the juice industries is widely recognized today. The development of EMR with naringinase activity is an attractive option for reducing bitterness that could replace current techniques, due to its high specificity and effectiveness, possibility of repeated and continuous use, and in order to retain the properties of juice as much as possible. The research therefore represents an advance in the application of biocatalytic membranes as technological alternative for juice debittering.     

葡萄柚种子提取物对真菌的抑制作用及其在葡萄和柿子保鲜中的应用

葡萄柚种子提取物是潜在的广谱性细菌、真菌杀菌剂,应该在果蔬保鲜中具有很好的效果.本研究选取比较容易受真菌感染的葡萄和柿子作为模式保鲜材料并且测试了葡萄柚种子提取物对8种与这两种水果腐败相关的真菌的抑制效果.结果表明,这8种真菌的最小抑制浓度分别在39.06×10-6至625×10-6之间不等.果实保鲜结果也证实了葡萄柚种子提取物对真菌具有很好的杀抑作用,延缓了果实的成熟,并且使保鲜的果实保留了较好的风味.这些结果可能与葡萄柚种子提取物富含多酚类物质有关,因为多酚类物质具有很强的抗氧化活性.     

柚子酒的研究进展

柚子不仅具有营养价值,同时还具有一些药用价值,深受消费者的喜爱。该文对柚子的营养活性成分、柚子及柚子酒的功效作用进行了介绍,对柚子酒的生产工艺及在酿造过程中存在的问题(柚子原料处理、发酵过程优化、陈酿过程优化)进行阐述,对柚子酒的技术开发进行了总结,以期为柚子酒的研究奠定基础。     

Edible coatings enriched with essential oils for extending the shelf‐life of ‘Bravo de Esmolfe’ fresh‐cut apples

Edible coatings based on sodium alginate (AL) and pectin (PE) at 1% and 2%(w/v) enriched with eugenol (Eug) and citral (Cit) at minimum inhibitory concentrations (MIC) (0.10% and 0.15%) and double MIC were used to preserve the quality of fresh‐cut apples ‘Bravo de Esmolfe’. Samples were taken, through 14 day at 4 °C, for analysis of colour CIE(L*h°C*), firmness, °Brix, weight loss, antioxidant activity (TEAC), microbial growth and taste panels. With those quality characteristics, three groups were formed by the principal component and hierarchical cluster analysis, for each coating base (AL or PE). Based on, for each quality parameter measured, the mean closest value to the one at harvest for colour, higher value for firmness, °Brix and TEAC, and lower value for weight loss and microbial spoilage, the best group was selected for AL and PE. From each group, two edible coatings with the highest scores in overall acceptability were selected for fresh‐cut apples: AL2% + Eug 0.1%, AL2% + Cit 0.15% + Eug 0.1%, PE 2% + Cit 0.15% and PE 2% + Eug 0.2%.     

Chitosan nanoparticle coatings reduce microbial growth on fresh‐cut apples while not affecting quality attributes

This study addressed the effects of chitosan‐based nanoparticles on microbiological quality, colour, polyphenol oxidase (PPO) and peroxidase (POD) and firmness of fresh‐cut ‘Gala’ apple slices during storage at 5 °C for 10 days. The treatments carried out were as follows: (i) slices pulverised with 110‐nm chitosan nanoparticles, (ii) slices pulverised with 300‐nm chitosan nanoparticles, (iii) 2 g L^?1 chitosan dissolved in 2% citric acid and (iv) noncoated samples. There was an increase in chroma and a proportional decrease in hue angle and lightness. Browning of the slices coated with conventional chitosan and control was slightly intense than those coated with chitosan nanoparticles of 110 and 300 nm. The PPO and PDO activities increased with time for all samples, with irrelevant difference among the treatments. Flesh firmness did not change for any treatment and period. Coatings with chitosan nanoparticles of 110 nm showed higher antimicrobial activity against moulds and yeasts, and mesophilic and psychrotrophic bacteria than the other treatments. No Salmonella, and total and faecal coliforms were detected. This investigation supports the potential use of chitosan nanoparticles as edible coatings in controlling microbial activity in fresh‐cut apples.     

Effects of Ultrasound on Spoilage Microorganisms,Quality, and Antioxidant Capacity of Postharvest Cherry Tomatoes

Mature‐green cherry tomato fruits (Lycopersicon esculentum cv. Jinyu) were exposed to different power densities of ultrasound (66.64, 106.19, and 145.74 W/L) at 25 °C to study ultrasound non‐thermal effects on the storage properties. Among the three levels of ultrasound irradiation, 106.19 W/L ultrasound was effective in reducing the spoilage microorganisms, delaying postharvest ripening through inhibiting ethylene production and respiration rates, and consequently maintaining fruit firmness, flavor, enzyme activities, antioxidants (total phenolics, total flavonoids), and the total antioxidant capacity of cherry tomatoes. The 66.64 W/L ultrasound had similar effects but to a lesser extent. Meanwhile, although 145.74 W/L ultrasound resulted in higher content of ascorbic acid (AA), it showed many negative effects on the storage quality of fruits. These results demonstrated that ultrasound of appropriate power density had great potentials in inhibiting decay, maintaining flavor and nutritional quality of cherry tomatoes.     

Recent advances in the use of edible coatings for preservation of avocados: A review

Avocados (Persea americana) are a fruit, whose shelf‐life is jeopardized by rapid ripening and fungal diseases, which heighten the necessity for postharvest treatments. The use of refrigeration during storage and transport helps delay the ripening process and phytopathogen growth but it is not enough to attenuate the problem, especially once avocados are placed in ambient temperatures. Fungicides are effective in controlling fungal prevalence, but their possible adverse environmental and human health effects have spurred interest in finding safer, natural substitutes. The objective of this paper is to review recent advances and trends in the use of edible coatings as a safe alternative to preserve and extend avocados shelf‐life. Edible biopolymer coatings have gained considerable attention due to their ability to extend fruit and vegetable shelf‐life. These coatings are a novel type of biodegradable primary packaging made from biological compounds like polysaccharides, proteins, lipids, and other polymers. Coatings are considered nonactive if they only form a physical barrier, separating avocados from their immediate environment, controlling gas and moisture transfer. Active coatings can contain supplementary ingredients with additional properties like antioxidant and antifungal activity. The application of edible coatings shows promising potential in extending avocado shelf‐life, replacing synthetic fungicides and reducing economic losses from avocado spoilage.     

GEO添加量对PLA/GEO复合膜性能及双孢蘑菇保鲜效果的影响

本文研究了不同浓度（0%、5%、7.5%、10%和12.5%）的葡萄柚精油（GEO）对聚乳酸(PLA)/葡萄柚精油复合膜的热性能,结构性能,机械性能,气体阻隔性能和抗菌性能等方面的影响。GEO通过减少聚合物链段的分子间作用力,从而改善复合膜的柔韧性,对复合膜起到一定的增塑作用。GEO的添加降低了PLA相的结晶性。随着GEO浓度的增加,复合膜的水蒸汽阻隔性能显著降低。但是,复合膜的抗菌活性因GEO的加入得以提高。将聚乳酸/葡萄柚精油复合膜应用于双孢蘑菇保鲜。结果表明,聚乳酸/葡萄柚精油复合膜与纯聚乳酸膜、低密度聚乙烯膜相比较,更能有效地保持蘑菇的硬度,阻止微生物生长,维持较好的总体接受度。因此,聚乳酸/葡萄柚精油复合膜可作为一种有效的包装材料,用于延长双孢蘑菇的货架期。