Reduction of Zygosaccharomyces rouxii Population in Concentrated Grape Juices by Thermal Pasteurization and Hydrostatic High Pressure Processing

How to comprehensively improve juice quality: a review of the impacts of sterilization technology on the overall quality of fruit and vegetable juices in 2010-2021, an updated overview and current issues

Fruit and vegetable juices (FVJ) are rich in nutrients, so they easily breed bacteria, which cause microbial pollution and rapid deterioration of their quality and safety. Sterilization is an important operation in FVJ processing. However, regardless of whether thermal sterilization or non-thermal sterilization is used, the effect and its impact on the overall quality of FVJ are strongly dependent on the processing parameters, microbial species, and FVJ matrix. Therefore, for different types of FVJ, an understanding of the impacts that different sterilization technologies have on the overall quality of the juice is important in designing and optimizing technical parameters to produce value-added products. This article provides an overview of the application of thermal and non-thermal technique in the field of FVJ processing over the past 10 years. The operating principle and effects of various technologies on the inactivation of microorganisms and enzymes, nutritional and functional characteristics, physicochemical properties, and sensory quality of a wide range of FVJ are comprehensively discussed. The application of different combinations of hurdle technology in the field of FVJ sterilization processing are also discussed in detail. Additionally, the advantages, limitations, and current application prospects of different sterilization technologies are summarized.

A Comprehensive Review on Grape Juice Beverage in Context to Its Processing and Composition with Future Perspectives to Maximize Its Value

Red and purple grape juices (GJs) have long been consumed worldwide for their unique taste and nutritive value. Moreover, grape is postulated to play an important role in the improvement of cardiovascular risk factors owing to its rich polyphenol content. Little is known regarding GJ’s holistic chemistry and functionality as compared to those of other fruit juices. This review aims to compile the state-of-the art chemistry of colored grape juices and in context to its analysis and nutritional values. Further, a review of potential contaminants to be introduced during manufacturing and other factors that influence juice quality and or health effects are presented to help maximize GJ’s quality. A comparison between analytical methods for juice QC establishment is presented employing hyphenated platforms versus direct spectroscopic techniques. The enrichment of the colored skin with a myriad of phenolics poses it as a functional beverage compared to that of skinless juice.

Graphical abstract

Ifs and buts of non-thermal processing technologies for plant-based drinks' bioactive compounds

Vegetables and fruits contain a variety of bioactive nutrients and non-nutrients that are associated with health promotion. Consumers currently demand foods with high contents of healthy compounds, as well as preserved natural taste and flavour, minimally processed without using artificial additives. Processing alternatives to be applied on plant-based foodstuffs to obtain beverages are mainly referred to as classical thermal treatments that although are effective treatments to ensure safety and extended shelf-life, also cause undesirable changes in the sensory profiles and phytochemical properties of beverages, thus affecting the overall quality and acceptance by consumers. As a result of these limitations, new non-thermal technologies have been developed for plant-based foods/beverages to enhance the overall quality of these products regarding microbiological safety, sensory traits, and content of bioactive nutrients and non-nutrients during the shelf-life of the product, thus allowing to obtain enhanced health-promoting beverages. Accordingly, the present article attempts to review critically the principal benefits and downsides of the main non-thermal processing alternatives (High hydrostatic pressure, pulsed electric fields, ultraviolet light, and ultrasound) to set up sound comparisons with conventional thermal treatments, providing a vision about their practical application that allows identifying the best choice for the sectoral industry in non-alcoholic fruit and vegetable-based beverages.

High Hydrostatic Pressure vs. Thermal Pasteurization: The Effect on the Bioactive Compound Profile of a Citrus Maqui Beverage

The effects of high hydrostatic pressure (HHP) compared to thermal pasteurization (TP) were studied in healthy citrus-maqui beverages. The impact of the processing technologies on the microbiological and phytochemical profile was assessed by applying two HHP treatments at 450 and 600 MPa for 180 s and TP at 85 °C for 15 s. The shelf life under refrigeration (4 °C) and room temperature (20 °C) was monitored for 90 days. All treatments ensured microbiological stability at both storage temperatures. Aside from that, the physicochemical parameters were not significantly different after processing or throughout the storage period. Regarding color parameters, an increase in the reddish coloration was observed during storage for those beverages treated by HHP. In general, phenolic compounds were little affected by the processing technique, even when treatment under HHP was more stable than by TP during storage. On the other hand, vitamin C showed great degradation after processing under any condition. It can be concluded that HHP is an effective alternative to thermal treatments, achieving effective microbial inactivation and extending the shelf life of the juices by contributing to a better preservation of color and bioactive compounds.

Ultrasound-Combined Sterilization Technology: An Effective Sterilization Technique Ensuring the Microbial Safety of Grape Juice and Significantly Improving Its Quality

: The effects of ultrasound (US), thermosonication (TS), ultrasound combined with nisin (USN), TS combined with nisin (TSN), and conventional thermal sterilization (CTS) treatments on the inactivation of microorganisms in grape juice were evaluated. TS, TSN, and CTS treatments provided the desirable bactericidal and enzyme inactivation, and nisin had a synergistic lethal effect on aerobic bacteria in grape juice while not having any obvious effect on the mold and yeast. Compared with CTS, the sensory characteristics of grape juice treated with TS and TSN are closer to that of fresh juice, its microbial safety is ensured, and the physicochemical properties are basically unchanged. More importantly, the total phenolic content and antioxidant capacity of juice treated with TS and TSN were significantly increased, and the total anthocyanin and flavonoid contents were largely retained. Taken together, these findings suggest that TS and TSN has great potential application value and that it can ensure microbial safety and improve the quality of grape juice.

Whole, concentrated and reconstituted grape juice: Impact of processes on phenolic composition, "foxy" aromas, organic acids, sugars and antioxidant capacity

The concentration and reconstitution processes of grape juices can result in losing compounds associated with beverage quality. In this context, three tanks containing 50,000 L of grape juice were individually concentrated up to 68 °Brix using a triple vacuum concentrator. The concentrated juice was reconstituted up to the original °Brix of the whole juice (18.4). Phenolic compounds, sugars and organic acids were quantified by high-performance-liquid-chromatography. "Foxy" aromatic compounds were also quantified by gas-chromatography/mass-spectrometry. The concentration and reconstitution process resulted in significant losses (Tukey test, p < 0.01) of trans-caftaric acid, decreasing from 397.08 to 159.14 mg/L, chlorogenic-acid from 34.97 to 8.44 mg/L, aromatic furaneol compound from 9.06 to 1.93 mg/L, as well as total losses for gallic-acid, caffeic-acid, p-coumaric-acid, syringic-acid, hesperidin, pelargonidin-3-glucoside and epicatechin compounds. The concentration and reconstitution of grape juice preserved the antioxidant capacity and most of the quantified compounds, with the reconstituted juice having good nutritional quality.

Comparison of High Hydrostatic Pressure, Ultrasound, and Heat Treatments on the Quality of Strawberry-Apple-Lemon Juice Blend

Changes in the microbial, physicochemical, and sensory properties of blended strawberry–apple–lemon juice were investigated to comparatively assess the influence of three processing treatments, namely high hydrostatic pressure (HHP) (500 MPa/15 min/20 °C), ultrasound (US) (376 W/10 min/35 °C), and heat treatment (HT) (86 °C/1 min) over 12 days of storage at 4 °C. The results showed that the total aerobic bacteria (TAB) counts in the HHP-, US-, and HT-treated juice blends were less than 2 log₁₀ CFU/mL, the yeast and mold (Y & M) counts were less than 1.3 log₁₀ CFU/mL, and the coliforms most probable number (MPN/100 mL) was less than 3 after 10 days at 4 °C. Anthocyanins were maintained by HHP, but decreased by 16% and 12% after US and HT, respectively. Total phenols increased by 18% and 7% after HHP and US, respectively, while they were maintained by the HT. Furthermore, better maintenance of total phenols, total anthocyanins, ascorbic acid, antioxidant capacity, color, and sensory values were observed in the HHP-treated juice blend stored for 10 days at 4 °C, compared to both the US- and HT-treated samples. Therefore, HHP was proposed to be a better processing technology for juice blend.