Effect of an UV-C Light-Based Hurdle Strategy for Carrot-Orange Juice Processing on Candida parapsilosis Inactivation and Physiological State: Impact on Juice Sensory and Physicochemical Quality Parameters

A multidimensional evaluation of the effects of sweetener selection and UV-C treatment on orange juice and pectin-based confectionery gels

BACKGROUND

Consumers are seeking healthier alternatives to traditional confectioneries. They value the use of sugar replacers, more natural ingredients and/or environmentally friendly preservation technologies. UV-C light is considered an emerging alternative to thermal pasteurization that leaves no residue and requires minimal energy. The present study aimed to investigate the effect of novel sweetener combinations and juice UV-C assisted by mild heat treatment (UV-C/H) on the physicochemical, microbiological, morphological, rheological and sensory properties of orange juice pectin-based confectioneries stored at 5 ± 1 °C for 35 days.

RESULTS

For orange juice processing, UV-C/H (pilot-scale Dean-flow reactor; 892 mJ cm-2 ; 50 ± 1 °C) and thermal (T-coil, 80 °C; 6 min) treatments were used. Low-calorie confectionery gels were elaborated using the treated juices, low-methoxyl pectin and various sweetener combinations. UV-C/H and T-coil effectively inactivated juice native microbiota. The proposed formulations, derived from a previous Box-Behnken optimization study, included partial (F1: 3%-sucrose-S + 0.019%-rebaudioside-A-RA) or complete sucrose replacement (F2: 5.5%-erythritol-E + 0.019%-RA), and one control (C:10%-S). In general, the microbiota of the gels prepared with the UV-C/H or T-coil treated juices did not recover during storage. The physicochemical and mechanical parameters of the formulations were significantly influenced by the choice of sweetener and the duration of storage. The gel surface got smoother and had fewer holes when the sucrose level dropped, according to a scanning electron microscopy study. The UV-C/H-treated samples did not differ in acceptability, whereas the measured sensory attributes approached ideal levels. F1 and F2 showed distinctive temporal-dominance-of-sensations profiles, mainly dominated by sweetness and orange taste, respectively. However, consumers perceived sourness and astringency in C during consumption.

CONCLUSION

The present study provides significant evidence in support of the development of confectionery gels F1 and F2 made from fruit juice treated by UV-C light assisted by mild heat and combinations of sucrose-alternative sweeteners. In terms of the properties investigated, these confectionery gels were comparable to, or even outperformed the full-sucrose option. © 2023 Society of Chemical Industry.

Inactivation of Alicyclobacillus acidoterrestris spores, single or composite Escherichia coli and native microbiota in isotonic fruit-flavoured sports drinks processed by UV-C light

Pasteurized sports drinks and other fruit-based beverages are susceptible to deterioration due to thermal processing ineffectiveness to inactivate certain spoilage microorganisms, like Alicyclobacillus acidoterrestris. This represents a major challenge for the beverage industry. The goals of this study were to: i) investigate the UV-C inactivation (annular thin film unit, actinometrical delivered fluence: 795-1270 mJ/cm², 10-15 min, 20 °C, 1.8 L/h, Re_h = 391-1067, recirculation mode operation) and the evolution during refrigerated storage of A. acidoterrestris ATCC 49025 spores and single or composite Escherichia coli ATCC 25922 in isotonic sports drinks (ISDs) made from orange (orange-ISD, UVT% = 81) or orange-banana-mango-kiwi-strawberry-lemon juices (multi-fruit-ISD, UVT% = 91), compared to a turbid orange-tangerine juice (OT juice, UVT% = 40); ii) assess the effect of pH, °Brix, A_254nm, turbidity, colour and particle size of the ISDs and juice on microbial inactivation, iii) evaluate the evolution of native microbiota during cold storage, iv) investigate the Coroller, biphasic, Weibull, and Weibull-plus-tail models' ability to describe microbial inactivation and v) measure 5-hydroxymethylfurfural (HMF) formation. The modified biodosimetry method was used to calculate the germicidal UV-C fluences. Heat pasteurization (T-coil, 80 °C/6 min) was evaluated as the control treatment. UV-C was highly effective at inactivating E. coli as 4.1-5.1 and 4.5-5.6 log reductions were determined in the multi-fruit-ISD and orange-ISD, respectively, barely impacted by the background microbiota. No significant differences were recorded for the inactivation of E. coli in the UV-C and T-coil systems. Whereas, a significantly higher inactivation of A. acidoterrestris spores was achieved by UV-C (3.7-4.0 log reductions), compared to the negligible one achieved by the thermal treatment. Even though E. coli inactivation curves were similar in shape, UV-C was less effective when a cocktail of other E. coli strains was present. In comparison to the OT juice, the ISDs' inactivation kinetics were markedly different in shape, with a rapid decrease in population during the first minutes of treatment. The germicidal fluence (H_{d biod}) corresponding to A. acidoterrestris (19.1 mJ/cm²) was selected as it was higher than the one obtained for E. coli (11.0 mJ/cm²). UV-C induced 2.8- or 1.3 and 2.3- or 0.8 log-reductions of total aerobes or moulds and yeasts in the multi-fruit-ISD and orange-ISD, respectively. Compared to the other models, the Coroller and biphasic models showed a better fit and more accurate parameter estimates. UV-C-induced HMF production was not significant in the ISDs. The current study found that the UV-C treatment was more effective than typical heat pasteurization for inactivating A. acidoterrestris spores in isotonic drinks, following a similar trend for E. coli and native microbiota.