Effect of initial oxygen concentration and film oxygen transmission rate on the quality of fresh‐cut romaine lettuce

Modified atmosphere packaging (MAP) is widely used to maintain the quality of fresh‐cut produce by matching the oxygen transmission rate (OTR) of the packaging film to the respiration rate of the packaged product. The effect of the interaction between film OTR and the initial headspace O₂ on quality of fresh‐cut vegetables has not previously been reported. Romaine lettuce leaves were sliced, washed, dried and packaged with film OTRs of 8.0 and 16.6 pmol s^?1 m^?2 Pa^?1, and with initial headspace O₂ of 0, 1, 2.5, 10 and 21 kPa. Packages were hermetically sealed and stored at 5 °C for up to 14 days. For samples packaged in 16.6 OTR film, increasing the initial headspace O₂ concentration delayed O₂ depletion within the packages, hastened the onset and increased the intensity of discoloration, and inhibited the development of CO₂ injury, acetaldehyde and ethanol accumulation, off‐odors and electrolyte leakage. With 8.0 OTR‐packaged lettuce pieces, ≤1 kPa initial headspace O₂ treatments induced an essentially anaerobic environment within the packages and increased acetaldehyde and ethanol accumulation and off‐odor development. Increasing the initial O₂ concentration above 1 kPa in 8.0 OTR packages transiently increased O₂ concentrations and reduced fermentative volatile production, off‐odors, electrolyte leakage and CO₂ injury. Regardless of initial headspace O₂ concentration, all 16.6 OTR‐packaged samples had severe discoloration after 14 days of storage. Quality was better maintained in 8.0 OTR‐packaged lettuce pieces as the initial headspace O₂ concentration was increased. A 21 kPa initial O₂ treatment of 8.0 OTR‐packaged lettuce maintained good quality throughout storage and had the best overall quality score. Copyright © 2005 Society of Chemical Industry     

Effects of UV‐C on antioxidant capacity,antioxidant enzyme activity and colour of fresh‐cut red cabbage during storage

Ultraviolet C (UV‐C) irradiation is a widely used nonthermal sterilisation method used to ensure the quality and safety of fresh and fresh‐cut produce. However, research focus of UV‐C has recently shifted from safety of sterilisation damage towards improvements in quality. Red cabbage (Brassica oleracea var. capitata f. rubra) is a widely consumed fresh‐cut vegetable. In this study, the effects of UV‐C irradiation on the antioxidant capacity, antioxidant enzyme activity and colour of fresh‐cut red cabbage were evaluated. The UV‐C decreased the L*, a* and b* values, and it turned the colour darker and increasingly blue. UV‐C increased the activity of four antioxidant enzymes and also stimulated the accumulation of flavonoids, glutathione and ascorbic acids. The antioxidant activity of UV‐C treatment was higher than in the control group. These results suggest that an appropriate dose of UV‐C may improve the antioxidant properties of fresh‐cut red cabbage.     

Mango film coated for fresh‐cut mango in modified atmosphere packaging

Mango puree is known to have good oxygen barrier properties. Therefore, mango film on its own might be useful to extend the shelf life of fresh‐cut mango. In this study, fresh‐cut mango was wrapped with mango film and packed in modified atmosphere packaging (MAP). Each package was stored at 30 °C or 5 °C and sensory evaluation was performed to determine its quality and shelf life. The shelf life of uncoated and coated fresh‐cut mango pieces was 6 days for each at 5 °C and was 3 and 4 days, respectively, at 30 °C. The sensory evaluation indicated that coated fresh‐cut mango was slower to produce an off‐flavour and maintained better visual quality than uncoated mango at 30 °C. Nonetheless, coated fresh‐cut mango was softer than uncoated mango because of the hydrophilic nature of the mango film. No significant difference in the oxygen and carbon dioxide concentrations was observed between coated and uncoated fresh‐cut mango. Coating fresh‐cut mango with mango film showed a similar effect to MAP in prolonging the shelf life of the fresh produce. The use of the coating will enhance fruit quality and lead to better acceptance by consumers.     

Microbiological hazards involved in fresh‐cut lettuce processing

BACKGROUND: The increasing consumption of produce all over the world has resulted in increasing concern by the regulatory agencies with respect to the level of safety performed by the processors. The objective of the present study was to investigate the hazards involved in the various steps of fresh‐cut lettuce processing (reception/selection of raw material, washing, rinsing, sanitisation and final product) by means of microbiological analyses of microbial groups used as indicators of hygienic conditions and of pathogens. RESULTS: High microbial loads of mesophilic and psychrotrophic bacteria and Pseudomonas spp. were found in the ram reception (～6 log colony‐forming units (CFU) g^?1), which were reduced by a single logarithmic cycle for the last two microbial groups after the sanitisation step (P < 0.05), the latter being ineffective against the first microbial group (P > 0.05). Lower counts of yeasts and moulds, total coliforms (35 °C) and faecal coliforms (44 °C) were observed in the initial step (3.49–4.53 log CFU g^?1, 0.65–1.55 log most probable number (MPN) g^?1 and 0.50–0.90 log MPN g^?1 respectively), these values increasing significantly after the sanitisation step for yeasts and moulds (～5 log CFU g^?1) but remaining unaltered for coliforms (P > 0.05). Salmonella spp. were not found in any of the experiments carried out, while the presence of Escherichia coli was observed in the final product. CONCLUSIONS : Practices compromising the hygienic quality of the final product during commercial storage were observed and corrective measures suggested. To the best of the authors' knowledge, these are the first data on microbiological safety in Brazilian fresh‐cut processing plants. Copyright © 2008 Society of Chemical Industry     

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     

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.     

Effect of substituting fresh‐cut perennial ryegrass with fresh‐cut white clover on bovine milk fatty acid profile

BACKGROUND

Including forage legumes in dairy systems can help address increasing environmental/economic concerns about perennial ryegrass monoculture pastures. This work investigated the effect of substituting fresh‐cut grass with increasing quantities of fresh‐cut white clover (WC) on milk fatty acid (FA) profile and transfer efficiency of dietary linoleic (LA) and α‐linolenic (ALNA) acids to milk fat. Three groups of three crossbred dairy cows were used in a 3 × 3 crossover design. Dietary treatments were 0 g kg^?1 WC + 600 g kg^?1 grass, 200 g kg^?1 WC + 400 g kg^?1 grass, and 400 g kg^?1 WC + 200 g kg^?1 grass. All treatments were supplemented with 400 g kg^?1 concentrates on a dry matter basis. Cows had a 19‐day adaptation period to the experimental diet before a 6‐day measurement period in individual tie stalls.

RESULTS

Increasing dietary WC did not affect dry matter intake, milk yield or milk concentrations of fat, protein or lactose. Milk polyunsaturated FA concentrations (total n‐3, total n‐6, LA and ALNA) and transfer efficiency of LA and ALNA were increased with increasing dietary WC supply.

CONCLUSION

Inclusion of WC in pastures may increase concentrations of nutritionally beneficial FA, without influencing milk yield and basic composition, but any implications on human health cannot be drawn. © 2018 The Authors. Journal of the Science of Food and Agriculture published by JohnWiley & Sons Ltd on behalf of Society of Chemical Industry.

     

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.     

Quality aspects of fresh‐cut ‘long‐storage tomato’ as affected by package,calcium chloride and storage time

In this research, some quality changes during storage at 4 °C were assessed in fresh‐cut fruits of a ‘long‐storage tomato’ landrace, packaged in biocompostable materials (PLA Ingeo tray/NatureFlex? film) or in conventional plastics (PET tray + polypropylene film). The effects of dipping in CaCl₂ on the shelf‐life extension were also assessed. Plants were cultivated both off‐season (greenhouse) and in‐season (open field). CO₂ and O₂ concentration, fruit weight loss, firmness, colour, microbial load were measured at 0, 4, 7, 12 days of storage. Headspace gas changes and fruit weight loss were minimised in conventional package. BIO package prevented water condensation, led to max 5% weight loss and made fruits less susceptible to spoilage. Dipping in CaCl₂ induced better firmness, especially in biopackage. Off‐season fruits had overall lower quality than in‐season fruits; however, these may contribute to extend the production season, with interesting marketing implications for the agri‐food industry.     

Effects of 1‐methylcyclopropene and post‐controlled atmosphere air storage treatments on fresh‐cut Ambrosia apple slices

BACKGROUND: The effect of 1‐methylcyclopropene (1‐MCP) treatment and two different post‐controlled atmosphere air storage (PCAAS) durations on the quality and chemistry of fresh‐cut Ambrosia apple slices was studied. RESULTS: PCAAS for 1 or 2 weeks prior to slicing had an overall positive effect on the resultant quality of fresh‐cut apple slices. The most significant responses to PCAAS were the suppression of both phenolic and o‐quinone accumulation in slices, and this was related to the significantly lower browning potential values obtained for slices from PCAAS‐treated apples. Polyphenol oxidase (PPO), peroxidase (POX) and ascorbate peroxidase (APOX) activities were not affected by 1‐MCP or PCAAS treatments. PPO and POX activities were almost completely inhibited by a 50 g L^?1 calcium ascorbate anti‐browning dip of apple slices from all treatments. CONCLUSION: The most dramatic effect of the PCAAS treatments was to reduce the accumulation of soluble phenolics, which is likely the reason that o‐quinone accumulation was also inhibited in treated fruits. The consequent reduction in browning potential may be the explanation as to why PCAAS treatment has been shown to reduce fresh apple slice browning in previous work. Copyright © 2012 Society of Chemical Industry     

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.     

Effectiveness of organic acid,ozonated water and chlorine dippings on microbial reduction and storage quality of fresh‐cut iceberg lettuce

BACKGROUND: The comparative effects of organic (citric and lactic) acids, ozone and chlorine on the microbiological population and quality parameters of fresh-cut lettuce during storage were evaluated. RESULTS: Dipping of lettuce in 100 mg L⁻¹ chlorine solution reduced the numbers of mesophilic and psychrotrophic bacteria and Enterobacteriaceae by 1.7, 2.0 and 1.6 log₁₀ colony-forming units (CFU) g⁻¹ respectively. Treatment of lettuce with citric (5 g L⁻¹) and lactic (5 mL L⁻¹) acid solutions and ozonated water (4 mg L⁻¹) reduced the populations of mesophilic and psychrotrophic bacteria by 1.7 and 1.5 log₁₀ CFU g⁻¹ respectively. Organic acid dippings resulted in lower mesophilic and psychrotrophic counts than ozonated water and chlorine dippings during 12 days of storage. Lactic acid dipping effectively reduced (by 2.2 log₁₀ CFU g⁻¹) and maintained low populations of Enterobacteriaceae on lettuce for the first 6 days of storage. No significant (P > 0.05) changes were observed in the texture and moisture content of lettuce samples dipped in chlorine, organic acids and ozonated water during storage. Colour, β-carotene and vitamin C values of fresh-cut iceberg lettuce did not change significantly (P > 0.05) until day 8. CONCLUSION: Lactic and citric acid and ozonated water dippings could be alternative treatments to chlorine dipping to prolong the shelf life of fresh-cut iceberg lettuce. Copyright © 2007 Society of Chemical Industry     

Improving quality of fresh‐cut mango using polysaccharide‐based edible coatings

This study was aimed at evaluating the effect of coatings with alginate (AL), pectin (PE), carboxymethyl cellulose (CMC) or chitosan (CH) on microbial stability, physicochemical attributes, total phenolics and carotenoids content, antioxidant capacity and sensory properties of fresh‐cut mango during 14 days at 4 ± 1 °C. Coated fresh‐cut mango kept microbial counts below 6 logs CFU g^?1, being CH‐coated fresh‐cut mango those that exhibited the lowest microbial counts (1 log CFU g^?1) along entire storage. AL, PE and CMC coatings maintained yellow colour of fresh‐cut mango throughout storage. AL and CH coatings, which have different monomers in their chain, improved the content of antioxidant compounds in fresh‐cut mango as related to uncoated. AL‐coated fresh‐cut mangoes were the toughest, among those coated, during 14 days. The highest consumer acceptance was achieved in AL (90.2%) coated fresh‐cut mango. CH would be the most suitable coating to extend the quality of fresh‐cut mango throughout storage.     

Effect of chitosan coating in preventing deterioration and preserving the quality of fresh‐cut papaya ‘Maradol’

BACKGROUND: Chitosan can form antimicrobial, semi‐permeable barriers that limit gas exchange and reduces water loss in fruits. Consumer interest in fresh‐cut papaya fruit is leading to increasing demand because of its sensorial and antioxidant properties. However, papaya is a highly perishable product that is prone to loss of weight, loss of firmness and microbial attack. The aim of this study was to evaluate the effect of chitosan coatings on the overall quality of fresh‐cut papaya. Chitosan coatings of low (LMWC), medium (MMWC) and high (HMWC) molecular weights, at concentrations of 0.01 and 0.02 g mL^?1, were applied to fresh‐cut papaya cubes. The treated cubes were stored at 5 °C and changes in quality were evaluated. RESULTS: MMWC maintained the highest color values (L* and b*) and firmness. Chitosan coatings suppressed mesophilic plate count, and the growth of molds and yeast, compared to controls. The MMWC coatings at 0.02 g mL^?1 resulted in the highest antimicrobial activity and decreased the activity of the enzymes polygalacturonase and pectin methylesterase, followed by low and high MW chitosan coatings at 0.02 g mL^?1. CONCLUSION: The application of the MMWC treatment at 0.02 g mL^?1 could be used to reduce deteriorative processes, maintain quality and increase the shelf life of fresh‐cut papaya stored at 5 °C. Copyright © 2008 Society of Chemical Industry