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• Thermosonication had non-significant effect on the physicochemical properties of juice. • Thermosonication promoted higher retention of ascorbic acid in comparison to thermal treatment. • Thermosonication enhanced the bioactive compounds. • Thermosonication significantly inactivated the microbial and enzymatic load. • The findings showed that thermosonication has the potential for industrial applications. The present work explores different conditions of thermosonication (TS) processing that would ensure microbiological and enzymatic safety for guava juice while simultaneously maximizing the preservation of its quality attributes. The guava juice was subjected to TS treatment (frequency: 40 kHz; power: 200 W; Temperature: 40, 60, and 80 °C; Time: 2, 6 and 10 min) and was compared with fresh and pasteurized (90 °C/60 s) juice samples. The objectives of the research work were to determine the effect of thermosonication on the quality attributes such as total soluble solids (TSS), pH, titratable acidity, cloud value, color attributes, total phenolic contents, total flavonoid contents, antioxidant activity, ascorbic acid levels, enzymatic, microbiological, and sensory properties. The thermosonicated and pasteurized samples showed no significant (p > 0.05) changes in pH, total soluble solids, and titratable acidity. TS improved the cloud value and color attributes. Furthermore, TS enhanced total phenols (10 to17%), flavonoids (5 to 25%), antioxidant activity (10.45% to 14.55%) and retention of ascorbic acid (61.98–83.32%) relative to control. Thermosonicated sample at 80 °C/10 min gives the maximum inactivation of Pectin methyl esterase (PME), Peroxidase (POD) and Polyphenol oxidase (PPO) enzymes. While both thermosonication and pasteurization drastically decreased the microbial count to undetectable levels, only TS exhibited modest improvement in sensory qualities. The results demonstrated that TS can enhance the overall safety, quality, and commercial viability of guava juice as a practical substitute to pasteurization. [ABSTRACT FROM AUTHOR]

The present work evaluated the effect of high-power ultrasonication on the structure and properties of guava juice. The microstructure, concentration of lycopene, in vitro accessibility of lycopene and physical properties (pulp sedimentation, turbidity and colour) were evaluated. The results of this study demonstrate that the ultrasonication disrupts the guava cells, releasing their content and altering the juice properties. Although this processing decreases the total amount of lycopene in guava juice, the release of lycopene from the cells increased its in vitro accessibility. Furthermore, the size reduction of the dispersed pulp particles improved the physical stability of the juice, avoiding pulp sedimentation without significant colour changes during storage. In conclusion, it is suggested that ultrasonication is an interesting alternative to improve the physical and nutritional properties of fruit juices. [ABSTRACT FROM AUTHOR]

The objective of the current study is to investigate the hydrolysis of pectinaceous matter in guava juice and to model the depectinization kinetics using commercial pectinase from Aspergillus niger . The procedure involves enzymatic treatment of guava juice at 45 °C with enzyme concentration (% w/w) 0.033, 0.055, 0.078 and 0.1. The degree of hydrolysis of pectinaceous matter and the rate of enzymatic reaction are determined. The results show an increase in the degree of hydrolysis with time for each enzyme concentration. Depectinization kinetics reveal allosteric behavior and is modeled using the Hill Equation. The image analysis of the sample using field emission scanning electron microscopy shows a change in the smoothness and homogeneity of the sample, indicating degradation of pectin network. [ABSTRACT FROM AUTHOR]

The thermophysical properties of guava (Psidium guajava L.) juice of the Thai seedless variety at medium maturity as affected by temperature and concentration were studied. The thermophysical properties were determined at concentrations between 10 and 40 °Brix and temperatures between 30 and 80 °C. The apparent viscosity (μ) and density (ρ) decreased with increase in temperature, while the specific heat capacity (Cps) increased as temperature increased. However, the thermal conductivity (k) was not influenced by temperature. The apparent viscosity (μ), and density (ρ) increased as concentration increased. [Copyright &y& Elsevier]

• Olfactory response in B. tryoni declined with increasing age in both sexes. • Male attraction to cue-lure declined dramatically after 12 weeks of age. • Females' strong attraction to guava-juice declined gradually after 6 weeks of age. • In females the decline was primarily caused by a drop in exploratory activity. • In males the decline was caused by reduced exploration and selective orientation. Olfaction is an essential sensory modality of insects which is known to vary with age. In short-lived insects odour response generally declines rapidly with increasing age, but how increasing age affects the olfactory response of long-lived insects is less known and there may be different life-time patterns of olfactory response. Here, we examine the effect of age on olfactory response and exploratory activity of a long-lived tephritid fruit fly, Bactrocera tryoni from sexual maturity (3 weeks) to advanced age (15 weeks). Males were tested against a male-specific attractant, cue-lure, which is associated with courtship and sexual selection in this species; while females were tested against guava-juice, a highly attractive oviposition host fruit odour. Trials were done in the laboratory using a Y-tube olfactometer at three weekly intervals. The probability of olfactory response of both males and females to tested odours declined with age. Males retained a constant attraction to cue-lure until 12 weeks of age, but then showed a significant drop in olfactory response at 15 weeks. However, females showed the highest attraction to guava-juice odour until six weeks of age and declined gradually thereafter. The change on odour response over time can be associated with an age-related change in initial locomotor activity for females as there was no change, over the life of the experiment, in selective female orientation to the odour source once flies started exploring within the olfactometer. However, for 15 week-old males, there was a simultaneous drop in both locomotor activity and selective olfactory orientation. The consistent attraction of male to cue-lure might be related to life-long reproductive activities of males, as males are thought to mate continuously during life. On the other hand, females' highest attraction to guava-juice odour in early life followed by a gradual decline might be linked with their oviposition rate which peaks in early life. [ABSTRACT FROM AUTHOR]