Heated Ascorbic/Citric Acid Solution as Browning Inhibitor for Pre-Peeled Potatoes

Treatment of pre-peeled potatoes with heated ascorbic acid (AA)/citric acid (CA) solution to extend shelf-life was investigated. Potatoes were abrasion or high pressure steam peeled, heated for 5–20 min in 1% AA + 2% CA at 45–55°C cooled, and then dipped for 5 min in browning inhibitor (BI) solution containing 4% AA +1% CA +1% sodium acid pyrophosphate. Combined treatment inhibited potato discoloration for 14 days at 4°C compared to 3–6 days with BI treatment alone. Raw material and treatment conditions were selected to minimize graying and textural abnormalities encountered with some treatments. Treatment with heated AA/CA may be an alternative to use of sulfites to control browning in pre-peeled potatoes.     

Effect of heat treatment and refrigerated storage on antioxidant properties of pre-cut celery (Apium graveolens L.)

This work studies the effect of two types of heat treatment, dry air at 48°C for 1 h and water immersion at 50°C for 90 s, and of storage time at 0°C on a number of quality parameters for pre‐cut celery: browning potential, soluble phenols content, total flavonoids, chlorogenic acid, ascorbic acid and antioxidant capacity. Pre‐cut celery was placed in crystal polyethylene terephthalate trays covered with polyvinyl chloride film. Samples were taken after 0, 1, 7, 14 and 21 storage days. Treatments reduced browning potential and chlorogenic acid content and, in addition, allowed ascorbic acid concentration to be retained for a longer time. For this reason, the application of heat treatments in minimally processed celery would be beneficial.     

Quality maintenance of minimally processed Chinese cabbage with low temperature and citric acid dip

Chinese cabbage (Brassica campestris L pekinensis group) was minimally processed using best preparation techniques and stored at 0 and at 5°C with and without dips in either citric acid, calcium chloride or ascorbic acid, all at 10 g litre⁻¹. The visual quality, degree of chilling injury, pH and taste were evaluated. The most deleterious effects on quality were produced by black speck (gomasho) and browning. Citric acid inhibited the development of black speck and extended storage life from 10 days of the control to 14 days at 5°C. At 0°C the storage life was not extended by any dip, but citric acid improved quality by reducing black speck. Minimally processed Chinese cabbage treated with citric acid showed only a slight reduction of pH from 6·3 of the control to 6·1 (P⩽0·05) and taste was not significantly affected (P>0·05). Microbial spoilage was not apparent during storage at 0°C for 35 days and 5°C for 21 days under any treatment. © 1997 SCI.     

Physiological and biochemical changes of different fresh-cut mango cultivars stored at 5 °C

Treatments to inhibit browning, decay and to extend shelf life of ‘Keitt’, ‘Kent’ and ‘Ataulfo’ mango cultivars as a fresh‐cut produce were investigated. Combinations of calcium chloride (CaCl₂), antioxidants [ascorbic acid (AA), citric acid (CA)] and two commercial film coatings resulted in a reduction of browning and deterioration of fresh‐cut mangoes stored at 5 °C, especially for the Ataulfo cultivar. The use of CaCl₂ + AA + CA significantly reduced colour deterioration, loss of firmness and did not affect sensory characteristics of fresh‐cut mango, with a larger effect in the Ataulfo cultivar. In general, these treatments prevented loss of sugar and vitamin C of cubes during storage at 5 °C. Shelf life of this cultivar was 21 days, while that of Keitt and Kent was only 9 and 12 days, respectively. There is a correlation between carotene and vitamin C content of Ataulfo mango and its longer shelf life compared with the other cultivars.     

Calcium Treatment to Maintain Quality of Zucchini Squash Slices

Zucchini squash slices dipped in solutions of CaCl₂ alone or with chlorine were stored at 0°C, 5°C, and 10°C. Slices developed water soaked areas (chilling injury) at 0°C and brown discoloration at 5°C and 10°C, which increased with storage. The amount and severity of chilling injury/browning/decay of water-dipped controls were least at 5°C. Calcium treatments helped in reducing development of decay, rate of total microbial growth, ascorbic acid loss, and shear force decrease of slices stored at 0°C and 10°C but not at 5°C. Addition of chlorine to CaCl₂ seemed to have some benefits at 0°C or 10°C.     

Inhibition of Browning of Harvested Head Lettuce

Treatments to control browning of lettuce stem discs (cv Iceberg) were evaluated by measuring changes in the L*, a* and b* parameters as well as Hue angle values. Cysteine, resorcinol, EDTA and citric acid prevented discoloration. Different concentrations of organic acids (citric, acetic and gluconic), vinegar and lemon juice were also tested. The best results were obtained when the discs were treated with 10 mL/L and 50 mL/L acetic acid solutions and vinegar. These treatments were then applied to head lettuces and browning was measured during 7 days storage at 2°C plus an additional commercialization of 3 days at 13°C. Vinegar and 50 mL/L acetic acid solution inhibited browning on lettuce stem cuttings and could be used to prevent lettuce butt discoloration during cold storage and commercial handling.     

PREVENTION OF BROWNING OF POTATO SLICES USING POLYPHENOLOXIDASE INHIBITORS AND ORGANIC ACIDS

Browning of minimally processed potato slices stored at low temperatures without active modification of the atmosphere in the storage container was inhibited by use of combinations of polyphenoloxidase inhibitors with organic acids. Slices of two cultivars‘Atlantic’and‘Russet Burbank’were dipped in solutions of various combinations of 4‐hexyl resorcinol, N‐acetyl‐cysteine and citric acid. Treated potato slices were kept in storage at 5C without browning or decrease in firmness for up to 21 days. The limiting factor in storage became visible microbial decay. Browning of slices from potatoes stored 1 month longer at 10C was also inhibited, but storage was limited to 14 days because of increased susceptibility to decay and decreased firmness with most treatments. However, no differences were found in inhibition of browning or retention of firmness of slices of the two cultivars after treatment with the combination of 0.25 M citric acid, 0.25 M N‐acetylcysteine and 0.01 M 4‐hexylresorcinol.     

POLYPHENOLOXIDASE ACTIVITY OF MINIMALLY PROCESSED 'JONAGORED' APPLES (MALUS DOMESTICA)

The influence of three chemical dips using ascorbic acid (AA), citric acid (CA) and calcium chloride (CC) on the polyphenoloxidase (PPO) activity and on the total phenolic content of minimally processed (MP) apple (Malus domestica, cv. Jonagored) during cold storage was evaluated and a potential relationship with enzymatic browning was investigated. An ascorbic acid dip (42.6 mM) of 5 min duration was the most efficient chemical treatment in reducing the PPO activity of apple cubes. A 92% inhibition was achieved after 7 days of storage at 4C. All treatments were advantageous in comparison to the control in reducing color changes. Color changes, determined by absorbance at 420 nm (soluble pigments) and lightness (L) (insoluble pigments) of apple cubes treated with ascorbic acid were correlated with total phenolic content. No correlation was observed between PPO activity and tristimulus color parameters, browning index or total phenolic content of AA‐treated apple cubes.     

Postharvest Physiology and Quality Maintenance of Sliced Pear and Strawberry Fruits

Sliced strawberries (cvs.‘Pajaro’ and 'G-3′) and partially ripe pears (cv.‘Bartlett’) were dipped in various solutions (citric acid, ascorbic acid, and/or calcium chloride) and stored in air or in controlled atmospheres (CA) for 7 days at 2.5°C followed by one day at 20°C. Fruit slices respired at a higher rate than whole fruits at both temperatures. CA storage suppressed respiration and ethylene production rates of sliced fruits. Firmness of strawberry and pear slices was maintained by storage in air + 12% CO₂ and in a 0.5% O₂ atmosphere, respectively, or by dipping in 1% calcium chloride. These treatments also resulted in lighter colored pear slices than the air control treatment.     

Effects of temperature,pH, organic acids,and sulfites on tagatose browning in solutions during processing and storage

Tagatose browning in solutions might be unacceptable to certain products containing tagatose during processing and storage. The objective of this study was to evaluate the effects of temperature, pH, organic acids, and sulfites on tagatose browning in solutions. Tagatose showed the fastest browning reaction, followed by fructose, xylose, glucose, and sucrose. Tagatose browning was temperature and pH dependent. As temperature and pH increased, tagatose browning was increased. Tagatose browning was slow at temperatures lower than 80°C and pH of 5. Organic acids, such as ascorbic acid, citric acid, and lactic acid, activated tagatose browning. Sodium bisulfite and potassium metabisulfite inhibited tagatose browning, whereas sodium sulfite had no effect on the inhibition of tagatose browning. During storage at 25°C, tagatose browning did not occur regardless of the pH, tagatose concentration, and storage time. It was suggested that tagatose browning in solutions might be prevented by controlling the temperature and pH.     

PREVENTION OF BROWNING OF BANANA SLICES USING NATURAL PRODUCTS AND THEIR DERIVATIVES1

Fresh-cut banana slices were treated with pineapple juice, neutral sugars, isoascorbic acid, citric acid, other organic acids, N-acetylcysteine, 4-hexylresor-cinol and mixtures of these compounds and evaluated for browning reaction. A number of other compounds previously reported to be antibrowning agents were also tested. Preliminary tests revealed that many purported antibrowning agents, including pineapple juice, had only transitory or no effects on browning of banana slices. Subsequent replicated treatments of slices stored at 5C and 15C for 7 days showed that of the several treatments, those using citric acid and N-acetylcysteine were highly effective at reducing browning. Reflectance measurements taken immediately after treatment, after 2 days of storage, and at the end of the 1 week storage period confirmed that a mixture of 0.5 M citric acid and 0.05 M N-acetylcysteine provided the best protection against browning at both temperatures. No microbial decay was observed during the 7 day period studied.     

INFLUENCE OF CHEMICAL TREATMENT ON QUALITY OF CUT APPLE (cv. JONAGORED)

The quality of a new variety of apple, ‘Jonagored’, after peeling and cutting was evaluated during ten days of storage in air at 4C. The objective was to evaluate the shelf-life of apple cubes by detecting the limiting parameter and to test the influence of different chemical dips on the cut apple quality with the aim of extending shelf-life. Color, i.e. browning at the cut surface, was found to be the critical quality parameter determining the shelf-life of the cut apple to less than three days. There were no significant differences between the dip treatments in measurements of CIE values. When apple cubes were treated with ascorbic acid, ascorbic acid plus calcium chloride or ascorbic acid plus calcium chloride and citric acid, the 0.75% ascorbic acid dip was found to be the most effective preservation treatment in terms of reducing color change of the cut surface. Both 0.75% ascorbic acid and 0.75% ascorbic acid plus 0.75% calcium chloride inhibited the loss of firmness of apple cubes. When citric acid was added to the dip treatment, there were color changes similar to those of the control.     

Protection of vessel permeability by genistein against lipopolysaccharide induced acute inflammation in a chick embryo chorioallantoic membrane model

Effects of dip treatments on nutritional quality preservation during the shelf life of fresh-cut tomato (Licopersicum esculentum Mill.) cv. Eufrates were investigated. Fresh-cut tomatoes were dipped in solutions of 2% ascorbic acid, citric acid, and calcium lactate for 2 min, then stored at 4°C for 20 days. Color (L*, a*, and b*), firmness, °Brix, phenolics, ascorbic acid content, antioxidant activity (DPPH), and sugars were measured during storage. Pathogen development was monitored, and a sensory evaluation was performed. Ascorbic acid was better in maintaining firmness. No treatments significantly affected °Brix, color, or sugars. Ascorbic acid maintained a higher antioxidant capacity, phenolics, and ascorbic acid content, and was better at reducing bacterial growth, while citric acid treatment was better at prevention of yeast and molds proliferation. Fresh-cut tomatoes showed good quality after 10 days of shelf life, except for flavor with the calcium lactate treatment. Ascorbic acid treatment better preserved the general and nutritional quality parameters.     

Novel Browning Inhibitor Formulation for Fresh-cut Apples

ABSTRACT: Development of a browning inhibitor for fresh-cut apples that would not support human pathogen survival was investigated. Granny Smith and Fuji wedges were treated with acidic or neutral browning inhibitors with and without addition of sodium hexametaphosphate. Wedges in modified atmosphere packaging pouches were observed for browning during storage at 4 °C and 10 °C. A pH 2.9 dip containing ascorbic acid, citric acid, and sodium hexametaphosphate suppressed browning for at least 3 wk at 4 °C, whereas formulations without hexametaphosphate failed within 1 wk. These results demonstrate that browning in fresh-cut apples can be controlled with a formulation unlikely to support human pathogen survival or growth.     

Browning Susceptibility and Changes in Composition During Storage of Carambola Slices

Browning and changes in the composition of sliced and whole carambola (Averrhoa carambola L.) fruit during storage were investigated. Susceptibility to browning after slicing, packaging and storage for 4 wk at 4.4°C varied considerably between four cultivars and five selections. There was no difference in browning susceptibility between fruit harvested at mature green or breaker stages of maturity. Freshly sliced carambola browned only slightly when exposed to air, but packaged slices that had been stored for 2 or more wk at 4.4°C browned rapidly (within 6 hr) when exposed to air. Whole fruit stored at 4.4°C for up to 6 wk, then sliced, showed much less susceptibility to browning. Ascorbic acid decreased and polyphenoloxidase activity increased in carambola slices during storage, but less in whole fruit. Treating slices with 1.0 or 2.5% citric acid + 0.25% ascorbic acid (in water) prior to packaging was very effective in limiting browning.     

Inhibition of browning by antibrowning agents and phenolic acids or cinnamic acid in the glucose–lysine model

The effects of antibrowning agents and phenolic acids or cinnamic acid on the inhibition of browning were investigated with a glucose–lysine model. Six antibrowning agents (cysteine, glutathione, sodium sulfite, pentasodium tripolyphosphate, citric acid and oxalic acid) and four phenolic acids (ferulic, hydroxybenzoic, syringic and vanillic acids) were used. In order to investigate the antibrowning capacity of these agents, model solutions containing glucose, lysine and an antibrowning agent were heated at 50 °C in the presence of FeCl₂, before being stored in nitrogen or air at 4 °C or 30 °C. Browning was accelerated to some degree during storage in air at 30 °C. In the case of storage at 4 °C, however, no browning was detected in nitrogen after four weeks. Citric acid was the most efficient antibrowning agent during storage in air at 30 °C and inhibited browning to 36% after four weeks. However, its antibrowning capacity was increased by 8–15% in the presence of any of the phenolic acids or cinnamic acid, essentially independently of concentration in the range 10 µM to 10 mM or the type of phenolic acid. Copyright © 2005 Society of Chemical Industry     

Time and Temperature Effect on Stability of Moroccan Processed Orange Juice during Storage

The loss of quality of processed pasteurized orange juice stored at 4°C, 22.5°C, 35°C, and 45°C for up to 14 wks was evaluated. The results showed that parameters such as pH, total solids, titratable acidity, formal index, and total sugars did not significantly change during storage at all temperatures. However, a major change was observed for ascorbic acid content, reducing sugars and furfural production, except for storage temperature at 4°C. Ascorbic acid degradation, sucrose hydrolysis, and furfural build-up followed pseudo-zero order reaction kinetics. The minimal change of formol number and total sugars suggested that nonenzymatic browning was mainly due to ascorbic acid degradation. Fufurfal formation during storage was found to be much higher than that reported in the literature.     

Influence of moderate heat pre-treatments on physical and chemical characteristics of kiwifruit slices

The effect of mild heat treatments, applied to whole kiwifruit, on physical characteristics and chemical composition of minimally processed fruit was studied. Fruits were subjected to heat treatments at 45 °C for 25 and 75 min, cooled for 24 h, minimally processed and stored at 4 °C for 12 days. Heat-treated fruits showed increased respiration rates in the first 2 days of storage. Samples colour was marginally affected either by heat treatments or by minimal processing. The application of heat treatments leads to an increment of slices firmness due to cross linking between demethylated galacturonic acid chains and endogenous calcium. An increment in sucrose, L-malic, citric, quinic and ascorbic acids was observed as a consequence of applied heat treatments. Heat treatment at 45 °C for 25 min applied to whole fruits allows quality retention of minimally processed fruit during 9 days at 4 °C.     

Antioxidant responses in minimally processed celery during refrigerated storage

This work studies the effect of storage temperature (0, 4 and 10 °C) and time on the antioxidant capacity of cut celery packaged in polystyrene trays sealed with PVC film. Samples were taken at 0, 7, 14, 21 and 28 days of storage to determine total phenols, chlorogenic acid and ascorbic acid. The browning potential and antioxidant capacity of the product were also evaluated. The antioxidant power presented similar behaviour for the three temperatures tested, decreasing after the first 7 days and then increasing up to day 14. Such increase coincided with an elevation of the ascorbic acid content, which was stronger for higher temperatures. As a general conclusion, minimally processed celery retained its initial antioxidant capacity for a period of 21 days at 0 °C, showing the lowest levels of browning potential at this temperature.     

ANTIOXIDANT ACTIVITY AND QUALITY OF MINIMALLY PROCESSED INDIAN CABBAGE (BRASSICA OLERACEA var CAPITATA)

The effect of different dip treatments and storage period on the antioxidant activity and biochemical quality of Indian cabbage for minimal processing was studied. A gradual decrease in total antioxidant activity was observed during storage at 6C with no detectable activity at the end of 9 days in all the dip treatments, except in treatments containing combination of ascorbic acid and citric acid, and ascorbic acid alone (10 g/L each). Possibility of considering antioxidant activity as a marker of shelf-life has also been proposed. Incorporation of ascorbic acid and citric acid in the dip water improved the overall appearance and retained the maximum antioxidant activity, ascorbic acid and total carotenoids. Based on the overall quality and appearance score, Golden Acre was found suitable for minimal processing with a shelf-life of 9 days.