Effects of aqueous ozone treatments on microbial load reduction and shelf life extension of fresh‐cut apple

Aqueous ozone was first used to take the place of chlorine as fresh‐cut apples sanitiser. Aqueous ozone (1.4 mg L^?1) treatments were evaluated for their effectiveness on microbial growth, quality attributes and shelf life of fresh‐cut apples. The results indicated that aqueous ozone treatments for 5 and 10 min achieved accepted microbial quality and, respectively, reduced total bacteria counts by 1.83 and 2.13 log₁₀CFU g^?1 compared with the control samples on the 12th day. The ethylene production, polyphenol oxidase and peroxidase activities, and total phenol and malondialdehyde contents were reduced by aqueous ozone treatments. In addition, this sanitiser also delayed the quality deterioration of fresh‐cut apples and enhanced their antioxidant capacity. Therefore, it was recommended to sanitise fresh‐cut apples with aqueous ozone (1.4 mg L^?1) for 5 min, which applied to industrial production requirement for both efficiency and costs and could extend the shelf life up to 10 days.     

Prediction of storage quality of fresh‐cut green peppers using artificial neural network

To extend the shelf‐life of fresh‐cut fruits and vegetables, it is essential to develop models that can accurately predict their storage quality. In view of this, an artificial neural network (ANN) model based on back propagation (BP) algorithm was developed to predict the storage quality (degree of yellowness, water loss, textural firmness and vitamin C content) of fresh‐cut green peppers. The prediction accuracy of ANN was compared with that of multiple linear regression‐based models. The root mean square error (RMSE), mean absolute error (MAE), sum of squared residuals (SSR) and standard error of prediction (SEP) were used as comparison parameters. The results showed that the accuracy and goodness of fit of the storage quality parameters predicted by ANN were better than those predicted by multiple linear regression‐based models. The RMSE, MAE, SSR and SEP values obtained from the former were much lower than those obtained from the latter.     

Effects of postharvest treatments on fruit quality of sweet pepper at low temperature

BACKGROUND: Postharvest storage of sweet pepper fruits (Capsicum annuum L.) at low temperatures could impair their physical and chemical composition. Therefore, maintenance of essential nutrition support or altered gas exchange could preserve fruit quality, minimizing chilling injury. Thus our aim was to determine the response to postharvest application of a low concentration of nitrogen (urea) or antitranspirant (pinolene) during a period of 21 days at 5 °C. RESULTS: The results indicate that storage at 5 °C was effective with respect to maintaining firmness of sweet pepper fruits for 21 days, while application of antitranspirant increased firmness compared with non‐sprayed fruits. Additionally, urea maintained color while increasing total phenolics and the activity of catalase and ascorbate peroxidase, lowering lipid peroxidation. Composition of free amino acids was affected to a minor extent. CONCLUSION: Maintaining quality is of paramount importance in the postharvest period. This study shows the effect of both temperature and spraying treatments with regard to maintaining fruit quality during this period, and provides new insights into the physiological role of enzymes of the antioxidant system during pepper storage at low temperature. Copyright © 2010 Society of Chemical Industry     

不同臭氧处理对甜瓜采后生理影响

以哈密瓜西州蜜17号为实验材料,在低温(6~8℃,RH80%~85%)环境下对甜瓜分别采取不同臭氧浓度(2.14、4.28、6.42 mg/cm~3)和不同间隔时间(12、24、48 h)处理,每次通入臭氧后进行密闭处理40 min,研究不同臭氧处理对甜瓜在整个贮藏保鲜42 d中的变化。结果表明:臭氧处理能够有效延缓相对电导率的上升,可滴定酸和抗坏血酸平均每天仅下降1.1%、1.2%,臭氧对其下降起到了明显的抑制作用,同时降低了23%的呼吸速率,推迟7 d出现呼吸高峰,腐烂指数仅为对照组的6.8%。臭氧浓度4.28 mg/cm~3、处理间隔时间24 h可以最好的保持甜瓜果实采后品质,延长了低温贮藏时间。本文为甜瓜采后贮运保鲜提供了可行的方法。      

Effect of ozone and calcium lactate treatments on browning and texture properties of fresh‐cut lettuce

The effects of three treatments, 1 mg L^?1 ozone at 18–20 °C, 15 g L^?1 calcium lactate (CLac) at 50 °C and a combination thereof, were compared on fresh‐cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P < 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (～9%) than ozone samples (～6%). Enzymatic activity decreased significantly (P < 0.05) in ozone samples. Polyphenol oxidase activity in fresh‐cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (<2500 units g^?1) and at the end of storage (<3000 units g^?1) than CLac samples (4000–4800 units g^?1). Ozone also reduced peroxidase activity to ～300 units g^?1 after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that CLac maintained quality markers better than treatments with ozone and ozone/CLac combination over 10 days of storage. Copyright © 2006 Society of Chemical Industry     

Surface treatments and coatings to maintain fresh‐cut mango quality in storage

BACKGROUND: Edible coatings may extend fresh‐cut fruit storage by preventing moisture loss and decreasing gas exchange. This study evaluated the effect of an antibrowning dip (calcium ascorbate, citric acid and N‐acetyl‐L ‐cysteine), followed or not with carboxymethylcellulose (CMC) or carrageenan coatings on quality of fresh‐cut mangoes stored at 5 °C for up to 20 days. A fourth treatment, only used in one of four experiments, consisted of chitosan. Treatments were applied on ‘Tommy Atkins’, ‘Kent’ and ‘Keitt’ mangoes harvested from Homestead (FL), and on imported store‐bought mangoes. RESULTS: The antibrowning dips maintained the best visual quality during storage for all cultivars, as indicated by higher b*, hue and L*. The CMC coating maintained similar visual quality, but carrageenan or chitosan decreased L* and b*. The antibrowning dip containing calcium ascorbate reduced firmness loss on cut pieces of ‘Keitt’, ‘Kent’ and store‐bought mangoes. The antibrowning treatment maintained higher titratable acidity for ‘Kent’ and ‘Keitt’, resulting in lower sensory sweetness. CONCLUSION: This study with repeated experiments showed that calcium ascorbate with citric acid and N‐acetyl‐L ‐cysteine maintained cut mango slices attractiveness in storage by keeping light color in both varieties. The addition of a polysaccharide coating did not consistently improve quality. Published in 2010 by John Wiley & Sons, Ltd.     

Optimization of processing of fresh‐cut pear

BACKGROUND: Successful processing of pears to render fresh‐cut fruits requires a thorough knowledge of their sensitivity to browning reactions, their respiratory metabolism, and their behaviour under modified atmosphere packaging. RESULTS: First, three different varieties of pear (Williams, Conference, Passacrassana) that had reached their commercial ripening stage were evaluated for suitability for minimal processing. Two antioxidant treatments were tested (treatment 1: 2% ascorbic acid + 1% citric acid + 1% CaCl₂; treatment 2: 2% ascorbic acid + 0.01% 4‐hexylresorcinol + 1% CaCl₂) to decide which one was the most effective against enzymatic browning. Finally, a modified atmosphere packaging was designed after two previous tests: measurement of respiratory activity of the peeled and cut pear at three temperatures (4, 15 and 25 °C); and evaluation of fruit tolerance to three different atmospheric compositions (21% O₂ + 10% CO₂; 2% O₂ + 0% CO₂; 2% O₂ + 10% CO₂). CONCLUSIONS: Conference pear was found to be the most suitable variety. Among the antioxidant treatments the one consisting of ascorbic acid, 4‐hexylresorcinol and CaCl₂ was proven to be the most effective against browning. The samples were packaged in a modified atmosphere with a composition of 10% O₂ + 10% CO₂ + 80% N₂. Copyright © 2008 Society of Chemical Industry     

Influence of aqueous ozone, blanching and combined treatments on microbial load of red bell peppers, strawberries and watercress

The effectiveness of ozone in aqueous solution treatment on microbial inactivation was studied for three combinations microorganism/food: Listeria innocua/red bell peppers (artificially inoculated), total mesophiles/strawberries, and total coliforms/watercress, with two concentrations (0.3 and 2.0 ppm). Blanching treatments (50-60 °C) were also individually applied and in combination with ozone, for studying possible synergistic effects. In relation to ozone treatments, the highest microbial reductions were obtained for the highest concentration with the highest treatment time (3 min). Under those conditions, L. innocua/peppers, total mesophiles/strawberries and total coliforms/watercress were reduced respectively 2.8 ± 0.5, 2.3 ± 0.4 and 1.7 ± 0.4 log-cycles. However, a substantial portion of the microbial populations were reduced by water washing alone, and the presence of ozone generally added an additional reduction of 0.5-1.0 log-cycles.If ozone at the highest concentration is used, the treatment impacts on L. innocua/peppers and total mesophiles/strawberries load reductions were equivalent to a blanching at 50 °C (for the same treatment times).Combining blanching and ozone did not generate synergistic effects, and in some situations microbial reductions were lower than the ones observed when treatments were applied independently.     

贮藏温度对湖南本地青椒采后理化品质的影响

目的研究贮藏温度对湖南本地青椒采后理化品质的影响,确定不同温度下青椒采后品质变化规律。方法考察不同温度(8℃和25℃)在贮藏20 d期间青椒理化品质变化,包括失重率、硬度、叶绿素含量、可溶性糖含量、有机酸含量、总酚含量及抗氧化活性(DPPH·清除能力、ABTS~+能力、FRAP能力)变化规律。结果同25℃相比, 8℃贮藏温度下青椒的理化品质保持更好。8℃处理组的青椒在贮藏期间失重率小,硬度较高,叶绿素、可溶性糖和有机酸含量变化幅度小,抗氧化活性较高。结论 8℃低温贮藏更有利于青椒采后理化品质的保持,延长其货架期。     

Quality of fresh‐cut products as affected by harvest and postharvest operations

There is a rising demand for fresh‐cut convenience products with high quality and nutritional standards that needs to be met by the fresh‐cut industry. It is well known that harvest and postharvest handling of fresh produce has a paramount impact on its quality and storage, although most of the existing literature has focused on these impacts related only to fresh produce that is destined for the final consumers. Indeed, current harvest methods and postharvest technologies have improved fruit and vegetable handling and distribution processes by slowing down physiological processes and senescence. Nonetheless, these technologies and methods may influence the quality of fresh produce as raw material for fresh‐cut processing as a result of the dynamic responses of fresh produce to handling procedures and treatments. Here, we review the existing literature on the challenges facing the fresh‐cut industry, focusing on the impact of harvest, maturity, and handling of fruit and vegetables on the quality of raw materials, as well as the implications for fresh‐cut products. The review also highlights areas for further research with the aim of enhancing the sensorial, nutritional and biochemical quality of such products. © 2018 Society of Chemical Industry     

臭氧处理对采后黄瓜贮藏品质的影响

目的研究不同浓度臭氧处理对采后黄瓜贮藏品质的影响。方法分别用浓度为1、3和5μg/mL臭氧处理用微孔膜包装的黄瓜15 min,每隔1 d处理1次,于7℃冷库中贮藏,并通过测定黄瓜硬度、可溶性固形物、可滴定酸、维生素C、叶绿素、丙二醛、过氧化物酶活性等指标来确定处理黄瓜的合适臭氧浓度。结果与对照组相比,采用5μg/mL浓度的臭氧处理可保持黄瓜较好的硬度,减缓叶绿素、抗坏血酸、可滴定酸和可溶性固形物等营养成分的降低,有效抑制丙二醛的积累,抑制过氧化物酶的活性。结论臭氧处理可以保持黄瓜的生理生化指标,提高黄瓜的贮藏品质,其中5μg/mL的臭氧处理效果最好。     

Effect of temperature and modified atmosphere packaging on overall quality of fresh-cut bell peppers

The effect of vacuum packaging (VP) and modified atmosphere packaging without vacuum (MAP) on shelf-life of fresh-cut green bell pepper stored at 5°C and 10°C were evaluated. In-package atmosphere, overall quality, percentage of leaked juice, texture, ascorbic acid content, ethanol and acetaldehyde, and microbial growth, were evaluated at different intervals of storage. MAP-fresh-cut peppers presented better visual quality, less leaked juice and higher firmness than those stored under VP. Microbiological and quality analysis revealed a limit of shelf-life of 14 and 21 days, when fresh-cut peppers were stored at 10°C and 5°C, respectively. We conclude that MAP could be used to maintain quality attributes of fresh-cut peppers for up 21 days at 5°C.     

The effect of washing on physicochemical changes in packaged, sliced green peppers

Whole green bell peppers (Capsicum annuum L.) were obtained through a local fresh‐cut company. They were washed in a 100 ppm chlorine solution, dried and then sliced into 0.5‐cm wide strips. A bulk sample of slices was divided into four treatments: (1) no wash, (2) one wash in fresh distilled water, (3) two sequential washes in fresh distilled water, and (4) three sequential washes in fresh distilled water. Retention of firmness of the pepper slices during storage at 7 °C improved with the number of washes after cutting. The modification of package atmosphere was less in all wash treatments than in the ‘no wash’ control. The sliced tissues of ‘no wash’ controls had higher levels of acetaldehyde and ethyl acetate. Analysis of the wash water revealed that sequential washes with water removed incremental amounts of acetaldehyde and soluble phenols from the cut surfaces of the tissue. These results show that washing has a dramatic effect on physicochemical measures of quality in green pepper slices, and it is likely that this effect is mediated by the removal of stress‐related compounds produced during the cutting operation. While acetaldehyde and total phenolics were the two stress‐related compounds measured in the wash water, it may be that other compounds removed in the wash water could have contributed to the beneficial effects on quality reported in this study.     

Combined effects of postharvest heat treatment and chitosan coating on quality of fresh‐cut mangoes (Mangifera indica L.)

The influence of heat treatment combined with coating on sensory quality, physico‐chemicals characteristics (firmness, colour, pH, titratable acidity, total soluble solids and total carotenoids content) and microbiological quality of fresh‐cut mangoes were studied. Whole mangoes (Mangifera indica cv ‘Tommy Atkins’) were subjected to hot water dipping (HWD) at 50 °C for 30 min and cooled for 15 min. Heated and unheated fruits were minimally processed and mango cubes were coated with chitosan solution (0.25% w/v) dissolved in 0.5% (w/v) citric acid, and stored for 9 days at 6 °C under ambient atmosphere. This study showed that both HWD 50 °C for 30 min and chitosan coating, either alone or combined, did not affect the taste and the flavour of mangoes slices. The chitosan coating combined with HWD or not inhibited the microbial growth for 9 days at 6 °C. Indeed chitosan coating was used for his antimicrobial proprieties. HWD 50 °C for 30 min was the beneficial treatment to maintain firmness and colour during 9 days at 6 °C.     

Effects of initial low oxygen and perforated film package on quality of fresh‐cut cabbages

The effects of perforated film packages (PFP) with different oxygen partial pressures (5, 8 and 10 kPa) and a barrier package (BP) at 21 kPa of O₂ on the quality of fresh‐cut cabbages were studied at 5 and 20 °C. The microbial growth, appearance, flavor, ascorbic acid content and polyphenol oxidase activity were determined during storage. The results indicated that fresh‐cut cabbages had better color retention and quality in PFP. Oxidation of ascorbic acid (AA) and browning of fresh‐cut cabbage were inhibited effectively using a PFP and an initial oxygen partial pressure equal to 5 kPa. Analysis of microbial growth also showed that the total count on fresh‐cut cabbage was relative lower in PFP with an initial low O₂ content. Loss of total ascorbic acid was much lower in PFP than that in BP by suppressing AA oxidation. The results of sensory evaluation showed that flavor and appearance were maintained effectively at 5 °C and significant differences in flavor were found between PFP and BP both at 5 and 20 °C, while significant differences in appearance were found between PFP and BP only at 20 °C. Copyright © 2007 Society of Chemical Industry