Biochemical changes of fresh-cut pineapple slices treated with antibrowning agents

Pectin-Based Edible Coating Combined with Chemical Dips Containing Antimicrobials and Antibrowning Agents to Maintain Quality of Fresh-Cut Pears

The aim of this study was to assess the effects of pectin coating alone (PE) or combined with chemical dips containing potassium sorbate (PS) or sodium benzoate (SB) as antimicrobials, and N-acetyl cysteine (N-AC) or ascorbic acid (AA) + citric acid (CA) as antibrowning agents, on weight loss, color values, browning index, firmness, titratable acidity, soluble solids content, total phenolic content, antioxidant activity and sensory attributes of fresh-cut pears during 15-day storage at 8 °C. Pectin coating delayed weight loss and improved firmness of fresh-cut pears as compared to control samples. Addition of either 1% N-AC or 1% CA + 1% AA in the formulation of the chemical dip protected the phenolic compounds and enhanced the antioxidant activity of fresh-cut pears during storage. PE + 0.2% SB + 1% N-AC and PE + 0.2% PS + 1% N-AC were the most efficient treatments in preserving color and reducing the browning index of fresh-cut pears during 15-day storage at 8 °C and received the highest scores for all sensory attributes throughout 12 days of storage. The results demonstrate the feasibility of PE + 0.2% SB + 1% N-AC and PE + 0.2% PS + 1% N-AC for extending the shelf life of fresh-cut pears.

Natural antioxidants of plant origin

Interest in the content of natural antioxidants in plant-based foods can be from the human health perspective, in terms of how these compounds might help promote one's health and wellness, or from the storage point-of-view, as the endogenous antioxidant constituents aid to extend a foodstuff's shelf-life. This chapter reports essential information about the mechanism of antioxidant action and methods employed for determination of their activity, classes of phenolic compounds (phenolic acids, flavonoids, lignans, stilbenes, tannins), sources of plant antioxidants (oil seeds, cereals, legumes, plants of the Lamiaceae family, tea and coffee, tree nuts, fruits, and berries), extraction strategies of phenolic compounds from plant material, and the influence of processing and storage on the content of natural antioxidants in foods and their antioxidant activity. Thermal processing, if not releasing bound phenolics from the structural matrices of the food, tends to decrease the antioxidant potential or, in the best case scenario, has no significant negative impact. Gentler sterilization processes such as high-pressure processing tend to better retain the antioxidant potential of a foodstuff than thermal treatments such as steaming, boiling, or frying. The impact of processing can be assessed by determining the antioxidant potential of foodstuffs either at the point of formulation or after different periods of storage under specified conditions.

Improving the shelf life of fresh-cut 'Royal Delicious' apple with edible coatings and anti-browning agents

The objective of this study was to monitor overall quality and to extend the shelf life of fresh-cut apple wedges. Fresh-cut apple wedges were treated with anti-browning agents and edible coatings alone as well as in combination and packed in polypropylene trays. Packed apple wedges were stored at 5 ± 2 °C and monitored for physical (colour, physiological loss in weight and firmness), bio-chemical (ascorbic acid, total antioxidant, phenol, polyphenol oxidase and peroxidase enzymes) and microbial quality. In general carboxymethyl cellulose and aloe vera coatings along with anti-browning agents helped in preserving quality of apple slices during storage. Microbial load was significantly low for wedges coated with carboxymethyl cellulose and aloe vera. Polyphenol oxidase and peroxidase enzyme activity was also low in the coated samples. Firmness of the uncoated apple wedges declined more rapidly than the coated ones during storage. The results showed that carboxymethyl cellulose and aloe vera coating in combination with anti-browning agents improved the quality of stored apple wedges.

Physicochemical, sensory, and nutritional quality of fresh-cut “Rojo Brillante” persimmon affected by maturity stage and antibrowning agents

To prevent enzymatic browning of fresh-cut ‘Rojo Brillante’ persimmon, different combinations of ascorbic acid (AA) and citric acid (CA) with calcium chloride (CaCl2) were tested in fruit harvested at two maturity stages (MS1 and MS2). Color, firmness, sensory quality, total vitamin C, radical scavenging activity, total phenolic content, and carotenoids were evaluated over nine days of storage at 5 ℃. Antibrowning dips reduced enzymatic browning if compared with the control samples. Selecting fruits with good firmness and the addition of 10 g/l CaCl2 help prevent loss of firmness of fresh-cut “Rojo Brillante” persimmons treated with acidic solutions as antibrowning agents to control enzymatic browning. The limit of marketability of the persimmon fruit processed at MS1 was significantly reduced by the burst of the disorder known as “flesh browning,” and only the samples treated with 10 g/l CA + 10 g/l CaCl2 maintained a limit of marketability close to seven days. At MS2, all the antibrowning solutions allowed a limit of marketability of seven storage days at 5 ℃. Nutritional quality was not affected by either antibrowning dips or cutting processes, but MS at harvest was.

Effect of soaking in noni (Morinda citrifolia) juice on the microbiological and color behavior of Haden minimally processed mango

The purpose of this study was to evaluate the effect of soaking in noni juice on the microbiological and color behavior of minimally processed mango. Two batches of Haden mango cubes were treated by immersion in noni juice for 2.5 or 5.0 min. Each batch was packed in polypropylene boxes and stored at 6 °C for up to 15 days; in addition, a control group of mango cubes was prepared by immersion in sterile water for the same duration. According to the results, the soaking of mango cubes in noni juice had an antimicrobial effect on mesophilic aerobic bacteria, molds and yeasts during storage at 6 °C for 15 days, without significantly (P < 0.05) affecting the CIE L*, a*, b*, chroma and hue angle values, in comparison with the control after 12 days of storage. The noni juice soaking treatment was demonstrated to be a potentially valuable technology for decontamination of fresh-cut fruit surfaces.

Application of edible coating and acidic washing for extending the storage life of mushrooms (Agaricus bisporus)

Hydrocolloid-based materials have been extensively used to coat fruit and vegetables to prolong shelf-life. The effects of different concentrations of acidic washing (acetic, ascorbic, citric and malic acids) followed by coating with gum arabic (GA), carboxymethyl cellulose and emulsified gum arabic (EGA) were evaluated on the weight loss (WL), firmness and color of mushroom. The WL of the uncoated mushrooms was significantly (p < 0.05) greater than that of the coated ones, and the minimum WL was obtained with EGA coating. The mushrooms washed with malic and ascorbic acids showed minimum and maximum of WL, respectively. Loss in firmness of the EGA-coated mushrooms was by 21% (the minimum of loss), while loss value of the uncoated ones was by 39% (the maximum of loss). Firmness of mushrooms was not influenced by the acid type. Concentration of the acid significantly (p < 0.05) influenced the firmness of mushrooms, and at the lowest concentration of acid (1%), the mushrooms tissue was firmest. The L* value of the mushrooms coated with GA was higher than that of others. A significant (p < 0.05) decrease in L* value and a significant (p < 0.05) increase in a* and b* values occurred in the mushrooms washed with acetic acid. Overall, washing with 1% citric or malic acid followed by coating with EGA resulted in minimum decrease in WL and firmness of the mushrooms.

Evaluation of the antioxidant properties of litchi fruit phenolics in relation to pericarp browning prevention

Phenolics were extracted from litchi fruit pericarp (LFP) tissues, purified and their antioxidant properties analyzed. LFP phenolics strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH*) and hydroxyl radicals and superoxide anions. The degradation of deoxyribose by hydroxyl radicals was inhibited by phenolics acting mainly as iron ion chelators, rather than by directly scavenging the radicals. Phenolics from litchi fruit pericarp were found to display similar reducing power activity as ascorbic acid. The effect of phenolic compound treatment on pericarp browning and electrolyte leakage of litchi fruit was also evaluated and it was observed that application of exogenous litchi phenolics to harvested litchi fruit significantly prevented pericarp browning and delayed increases in electrolyte leakage. These results suggest that litchi pericarp tissue phenolics could be beneficial in scavenging free radicals, maintaining membrane integrity and, thereby inhibiting pericarp browning of litchi fruit.