Optimization of Prickly Pear Juice Clarification for Better Retention of Betalain and Color Properties

Background: Prickly pear juices are considered as valuable ingredient for sports and energy drinks due to its higher amino acids contents, minerals and attractive red color. Hence, prickly pear fruit has received renewed interest for the production of juice. Up to date, relatively little work has been reported regarding the manufacturing of prickly pear products. Enzyme has proved to be the key element for producing clear and stable fruit juice. The present study aimed to optimize the processing parameters for enzymatic clarification of prickly pear juice. The results of this investigation are expected to provide the suitable process technology for the production of prickly pear juice with better retention of betalain content and color value. Methods: Prickly pear pulp was treated with pectinase enzyme at different concentrations (0.01-0.09%), incubation temperatures (40-60°C) and incubation time (60-180 min). The effect of enzymatic treatments on clarity, color index, betalain content and ascorbic acid content of juice were studied through response surface methodology by employing second order central composite rotatable design. Result: Response surface analysis determined the optimum condition for clarifying prickly pear juice as 0.036% enzyme concentration, 46°C incubation temperature and 112 min incubation time. At this condition, it was predicted to produce the prickly pear juice with clarity of 48.59% T, color index of 0.603 abs, betalain content of 542.93 mg/L of juice and ascorbic acid content of 9.35 mg/100 g with the desirability of 0.780.

Phenolics Profile, Antioxidant Activity and Flavor Volatiles of Pear Juice: Influence of Lactic Acid Fermentation Using Three Lactobacillus Strains in Monoculture and Binary Mixture

The aim of this study was to evaluate the effects of lactic acid fermentation using three Lactobacillus strains (Lactiplantibacillus plantarum 90, Lactobacillus helveticus 76, and Lacticaseibacillus casei 37) in monoculture and binary mixture on phenolics profile, antioxidant activity and flavor volatiles in pear juice. Results showed that the colony counts of binary mixture were higher than monoculture in fermented pear juice. The total content of phenols was increased, while that of flavonoids was decreased significantly during fermentation (p < 0.05). Antioxidant activities in fermented peer juice including DPPH and ABTS radical scavenging abilities and ferric reducing antioxidant power (FRAP) were significantly improved (p < 0.05). Binary mixture of Lactiplantibacillus plantarum 90 and Lacticaseibacillus casei 37 fermentation exhibited strong DPPH radical scavenging ability, due to the increase in vanillic acid and arbutin contents. Furthermore, lactic acid fermentation improved the formation of alcohols, esters, acids and terpenoids, and reduced the contents of aldehydes and ketones. Thirty new compounds including 15 alcohols, seven esters, five acids, and three terpenoids were observed in fermented pear juice. Hierarchical cluster revealed that flavor volatiles in pear juice were improved dramatically by Lactobacillus strains fermentation, and there were dramatic differences between monoculture and binary mixture.

Clarification Processes of Orange Prickly Pear Juice (Opuntia spp.) by Microfiltration

In this study, fresh orange prickly pear juice (Opuntia spp.) was clarified by a cross-flow microfiltration (MF) process on a laboratory scale. The viability of the process—in terms of productivity (permeate flux of 77.80 L/h) and the rejection of selected membranes towards specific compounds—was analyzed. The quality of the clarified juice was also analyzed for total antioxidants (TEAC), betalains content (mg/100 g wet base), turbidity (NTU) and colorimetry parameters (L, a*, b*, Croma and H). The MF process permitted an excellent level of clarification, reducing the suspended solids and turbidity of the fresh juice. In the clarified juice, a decrease in total antioxidants (2.03 TEAC) and betalains content (4.54 mg/100 g wet basis) was observed as compared to the fresh juice. Furthermore, there were significant changes in color properties due to the effects of the L, a*, b*, C and h° values after removal of turbidity of the juice. The turbidity also decreased (from 164.33 to 0.37 NTU).

Characteristics of Volatile Compounds and Sensory Properties of Mixed Organic Juices Based on Kiwiberry Fruits

Nowadays, the trend related to healthy eating is constantly growing among consumers. The juices based on kiwiberry containing over 20 vital nutrients may have a potential for usage in developing innovative products targeting health-concerned consumers. The aims of the study were: (1) to identify the volatile compounds of kiwiberry juice and its mixes with basic organic juices; (2) to determine the sensory characteristics and level of liking with regard to the tested samples and (3) to select the juice-mix with the highest sensory quality properties and liking. The measurements of volatile compounds in juices were made using a Heracles Neo ultrafast gas chromatograph (HS-GC). The sensory characteristics of the juices were assessed by Descriptive Quantitative Analysis, whereas the consumers’ overall liking was assessed on a 9-point hedonic scale. It was stated that the examined juices differed in the pattern of volatile compounds as well as in the sensory properties and the level of liking. The increasing addition of apple and pear juice to kiwiberry based juices in different ratios contributed to the exposed volatile compounds responsible for floral, sweet and fruity odours. The juice mixes with higher addition of apple or pear juices were more harmonized in terms of sensory image and represented higher levels of overall liking among consumers.