Browning Of Apple Juice Research Articles

Kinetic modelling of non-enzymatic browning of apple juice concentrates differing in water activity under isothermal and dynamic heating conditions

The kinetics of non-enzymatic browning in apple juice concentrates were investigated. The effect of a w (in the range of 0.74–0.99) and/or reactant concentration on brown pigment formation was monitored under isothermal heat treatment at four temperatures (60, 70, 80 and 90 °C) in apple juice solutions having either the same or different concentrations of reactant solutes. The extent of the Maillard reaction was evaluated by spectrophotometric measurements at 420 nm ( A 420). The absorbance–time curves were fitted to five different kinetic models (zero and first order, weibull, logistic and the parabolic model) and estimates of browning rate constants and other model parameters were obtained. Regression analysis revealed that the logistic model was the most appropriate for describing browning in apple juice. The initial reactant concentration, but not water activity, had a significant effect on the colour change of apple juice. The processing temperature also had a strong impact on browning kinetics. Secondary models, expressing the dependence of the best fitted primary model parameters on temperature and a w, were further developed and validated by comparing the predicted model parameters with the values observed in independent isothermal experiments. Finally, the derived model was further evaluated against the observed browning responses of apple juice under dynamic heating conditions, underlining the applicability of the developed model as a practical prediction tool for the study of non-enzymatic browning.

Thermostabilities of plant phenol oxidase and peroxidase determining the technology of their use in the food industry

Stabilities of phenol oxidase and peroxidase from tea plant (Camellia sinensis L.) clone Kolkhida leaves, apple (Malus domestica L.) cultivar Kekhura fruits, walnut (Juglans regia L.) green pericarp, and horseradish (Armoracia lapathifolia Gilib) roots were studied using different storage temperature modes and storage duration. It was demonstrated that both enzymes retained residual activities (approximately 10%) upon 20-min incubation at 80 degrees C. Phenol oxidases from tea, walnut, and, especially, apple, as well as tea peroxidase were stable during storage. A technology for treatment of plant oxidases was proposed, based on the use of a natural inhibitor phenol oxidase and peroxidase, isolated from tea leaves, which solving the problem of residual activities of these enzymes, arising during pasteurization and storage of beverages and juices. It was demonstrated that browning of apple juice during pasteurization and beer turbidity during storage could be efficiently prevented using the natural inhibitor of these enzymes.

Kinetics of Inhibition of Polyphenol Oxidase Mediated Browning in Apple Juice by β-Cyclodextrin and L -Ascorbate-2-triphosphate

Polyphenol Oxidase (PPO) mediated browning in raw fruits and vegetables is a major cause of quality deterioration in fruits and vegetables and derived food products. Here the rate of browning reaction in apple juice treated individually and in combination(1:1) of β -Cyclodextrin (β -CD) and L -Ascorbate-2-triphosphate (L -AATP) is described. It was observed that the rate of quinone formation can be minimized using a combination of β -CD and L -AATP as compared to individual treatment with these agents. Kinetic experiments revealed that both compounds are non-competitive inhibitors of PPO.

Effect of storage on nonenzymatic browning of apple juice concentrates

Kinetics of nonenzymatic browning in Golden Delicious and Amasya apple juice concentrates during 4 months are investigated. Apple juice concentrates were at 65, 70, 75°Bx of Golden Delicious variety, stored at 5, 20, 37 °C and Amasya variety, stored at 37, 50, 65 °C. Colour development was measured by browning index ( A 420) and the CIE-Lab colour system. Browning level of all apple juice concentrates increased according to a zero-order reaction kinetic. Activation energies for 65–75°Bx of Golden Delicious and Amasya apple concentrates ranged from 21.4 to 21.0 kcal/mol and 33.7 to 32.5 kcal/mol, respectively. Influence of soluble solids content on browning was negligible. HMF concentration, in Golden Delicious apple juice concentrates, was between 0.52 and 963 mg/kg, and between 0.52 and 190 mg/kg in Amasya apple juice concentrates.

Inhibition of enzymic browning in cloudy apple juice with selected antibrowning agents

Golden Delicious apple juice was subjected to enzymic browning in the presence of the selected antibrowning agents: ascorbic acid, isoascorbic acid, l-cysteine, sorbic acid, benzoic acid, cinnamic acid and β-cyclodextrin. The relative effectiveness of these antibrowning agents for inhibition of enzymic browning in apple juice was determined in terms of colour and enzyme activity measurements with respect to time for approximately one day storage period at 25±1 ° C . The most effective agents were determined as l-cysteine, cinnamic acid and ascorbic acid. Response surface methodology was used to evaluate the potency of the l-cysteine, ascorbic acid and cinnamic acid combination for the control of enzymic browning. The ascorbic acid, l-cysteine and cinnamic acid combination provided better results than the individual compounds. The optimum combination was determined as 0.49 mM ascorbic acid, 0.42 mM l-cysteine and 0.05 mM cinnamic acid in the cloudy apple juice stored for 2 h at 25±1 ° C .

Gamma-Radiation influences browning, antioxidant activity, and malondialdehyde level of apple juice.

Apple juice was gamma-irradiated at 5 degrees C at doses ranging from 0 to 8.9 kGy and then stored at 5 degrees C for 15 days. Ionizing radiation reduced the browning of apple juice and increased antioxidant activity measured by the ferric-reducing antioxidant power (FRAP) assay. The magnitude of changes increased with radiation dose. The level of malondialdehyde (MDA) measured using the thiobarbituric acid reactive substrates assay increased at radiation doses above 2.67 kGy. The browning of irradiated juices increased during storage at 5 degrees C, but the irradiated juices were still lighter than controls at the end of storage. Differences in FRAP values disappeared during early periods of storage while higher MDA levels were observed in irradiated samples during most of the storage period. Elimination of suspended matter from apple juice did not alter irradiation-induced changes in browning, FRAP, or MDA formation. As compared to irradiation conducted at 5 and 20 degrees C, treatment at -15 degrees C was less effective in reducing browning and in increasing MDA formation but elevated FRAP values. The exclusion of oxygen from juices did not affect the reduction in browning due to irradiation but promoted the increase in FRAP values and decreased the irradiation-induced MDA formation.

タマネギ搾汁液によるリンゴの切片およびジュースの褐変防止

The effect of onion juice on the browning of slices and juice of apple was examined. The browning of apple slices was completely suppressed by dipping them in onion juice diluted with an equal volume of water for 10 minutes. The browning of apple juice was, likewise, inhibited when the 50% apple juice was prepared by the addition of an equal volume of onion juice. Though the polyphenol oxidase activity of the apple was inhibited about 80% by the onion juice, 20% of activity still remained. Because the reaction liquid does not change to yellow, even if the reaction progresses in this condition, it was suggested that the formation of the browning material had been inhibited by the onion juice reacting wich the product by 20% the remainder polyphenol oxidase activity.

Inhibition of Enzymatic Browning in Fresh Fruit and Vegetable Juices by Soluble and Insoluble Forms of β-Cyclodextrin Alone or in Combination with Phosphates

Soluble and insoluble forms of β-cyclodextrin (β-CD) can be used to inhibit enzymatic browning of fresh raw apple, pear, white grape, and celery juice. The anti-browning effects of soluble CDs were concentration-dependent. Concentrations (1−1.5% w/v) of soluble (un-derivatized, hydroxyethyl, or maltosyl) β-CD substantially inhibited browning of Granny Smith apple juice held at room temperature for several hours while untreated juice browned in minutes. Higher concentrations (4−10%) of soluble β-CD derivatives completely inhibited the browning of apple juice held for 1 day under these conditions. The effectiveness of β-CD was greatly enhanced by the presence of phosphate-containing compounds. Hence, only 1% levels of soluble β-CD (in the presence of 0.25−0.5% phosphate compound) completely inhibited browning in apple juice held for 1 day at room temperature or for up to 2−3 weeks at 4 °C. Treatment of apple, pear, white grape, and celery juice with an insoluble form of β-CD, either in a batchwise or flow-through process, resulted in juices free of CDs that resisted browning indefinitely. Keywords: Enzymatic browning; inhibition; cyclodextrins; vegetable and fruit juice; phosphates; phytic acid

Relationship between Apple Ripening and Browning: Changes in Polyphenol Content and Polyphenol Oxidase

Changes in the browning of apple juice, polyphenol content, and polyphenol oxidase were examined during apple ripening. The degree of browning of apple juice, the phenol content per gram of flesh, and the polyphenol oxidase (PPO) activity per milligram of protein decreased during ripening. From 4.5 to 6 months after flowering, the amount of PPO per milligram of protein, determined by an enzyme-linked immunosorbent assay, was constant, but its specific activity decreased, suggesting that PPO had denatured. PPO was uniformly distributed in the immature and mature apple, but active PPO was mainly localized around the core in the mature apple.

Sulfated polysaccharides inhibit browning of apple juice and diced apples

Sulfated polysaccharides inhibit browning of apple juice and diced apples

Effect of Emulsifying Agents on Inhibition of Enzymatic Browning in Apple Juice by Ascorbyl Palmitate, Laurate and Decanoate

ABSTRACTThe effects of emulsifying agents (EA) on the stability of aqueous dispersions of ascorbyl palmitate (AP), laurate (AL), and decanoate (AD), and on the effectiveness of these compounds as browning inhibitors in apple juice were investigated. The stability of 1.14 mM AP, AL or AD, dispersed in simulated juice, was greatly improved by the addition of hydrophilic EA's such as Tween 60. More lipophilic EA's also were effective in stabilizing AL and AD dispersions. However, the addition of EA's to these browning inhibitors failed to improve their effectiveness in juice and, in the case of Tweens, had a detrimental effect. These results are attributed to the solubilization or activation of bound polyphenol oxidase.

Nonenzymatic Browning in Apple Juice Concentrate during Storage

ABSTRACTRate of browning in Red Delicious and Granny Smith apple juice concentrates during storage was investigated. Color development at 65°, 70° and 75°Brix and storage temperatures of 5°, 20° and 37°C were compared over 120 days. Color deterioration occured at a faster rate in Red Delicious. Reaction at different concentration and storage conditions was exponential, following an Arrhenius‐type dependence with temperature. Activation energy for a solids content of 65 ‐ 75°Brix ranged from 16.4 ‐ 19.3 Kcal/mole. Influence of juice variety on activation energy was negligible. Water activity results are in general agreement with those reported by other investigators. A satisfactory correlation to predict commercial concentrate browning has been obtained. All other things being equal, thermal history is a critical factor to obtain a lighter color concentrate.

The control of enzymic browning in fruit juices by cinnamic acids

SummaryThe use of cinnamic, p‐coumaric and ferulic acids to control the browning of apple juice has been investigated. Concentrations of cinnamic acid greater than 0.5 mM effectively prevented browning for over 7 hr. A simple method for estimating the minimum concentration of inhibitor required for a particular variety or blend of juice is outlined.

Less grown apple varietes in juice production, and the influence of polyphenols and added ascorbic acid on the juice quality

Three apple varieties, Atlas, Erstaa, and Dolgo, were studied for their suitability for juice production and for the effect of polyphenols and added ascorbic acid on the juice quality. The Atlas and Erstaa varieties were found to be very suitable as raw material for apple juice production. The juices of Atlas were best in quality but they were sensitive to browning while Erstaa juices were not. The juices of Dolgo were considered too tart, but with an exceptionally interesting flavour. Dolgo juices could probably be used in mixtures together with sweeter apple varieties. Ascorbic acid could be used to prevent browning or to stop it to the desired degree and to stabilize the colour of the juice. The second alternative was found to be better because light brownish apple juices are generally preferred. The browning of apple juice was influenced not only by the polyphenolase activity and the polyphenol concentration but also by the type of phenolic compounds. In this respect proanthocyanidins and flavanols were most significant.

Action of A ring‐cleaving oxygenase in preventing oxidative darkening of apple juice

AbstractPrevention of browning of apple juice by catechol oxidase was brought about through enzymic cleavage of the aromatic ring of juice‐darkening constituents. Protocatechuate‐3,4‐dioxygenase in the presence of ascorbate oxidatively attacked the catechol compounds in juice, nullifying their darkening capacity.