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Background: Adding value to conventional fruit juices by including prebiotic compounds into their formulation and preserving them using non-thermal, eco-friendly and safe technologies represent interesting and strategic approaches to diversify healthy and innovative food products. In this context, the effect of ultrasound-assisted processing (for 15 and 30 min, 40 kHz, 180 W) on microbiological, physicochemical, nutritional and sensory quality of prebiotic-rich strawberry juices was investigated during storage (14 days, 5 °C)., Results: Compared to untreated samples, the applied preservation treatments enhanced the microbiological and nutritional quality of samples by significantly reducing native microflora counts (reductions up to 1 log CFU mL -1 at day 14) and increasing the total phenolic content (by more than 25% in comparison to controls at day 14) leading to higher antioxidant capacity of prebiotic-rich strawberry juices. Ultrasound processing and prebiotic enrichment had no negative effect on sensory attributes of enriched samples, suggesting that this non-thermal technique successfully retained the fresh-like attributes of strawberry juices during their shelf-life, contributing to the good sensory stability of juices. In addition, ultrasound treatments had no detrimental impact on physicochemical quality and ascorbic acid content of enriched samples, showing similar stability to control samples during storage., Conclusions: Based on our results, ultrasound processing appears to be a promising non-thermal technique for ensuring a stable product from both microbiological and sensory points of view with improved antioxidant capacity and unaltered physicochemical quality while offering a healthier, nutritive and valuable food alternative. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Background: The quantification of the main carbohydrates present in strawberry juices enriched with inulin and fructo-oligosaccharides (FOS) and preserved by non-thermal techniques (vanillin and ultrasound) was conducted, in addition to an investigation of the evolution of these compounds and their relationship with fungal deterioration over 14 days of refrigerated storage., Results: A simple and environmentally friendly analytical approach based on high-performance liquid chromatography with a reflection index detector was developed for simultaneous determination of inulin, FOS and mono- and disaccharides present in the juices. When analyzing the evolution of carbohydrates during storage, a direct relationship between the consumption of sucrose and the growth of yeasts and molds (main spoilage flora in strawberry) was observed, especially in untreated samples (control). By contrast, no sucrose consumption was observed during storage of the treated sample, thus demonstrating the efficiency of the non-thermal treatments for controlling yeasts and mold growth. In turn, inulin and FOS added to juices were not degraded during storage., Conclusion: The results obtained in the present study demonstrate that non-thermal treatments are adequate for preventing the growth of deteriorative flora in strawberry juices and that the addition of inulin and FOS can be a good strategy for functionalizing them, as well as improving their nutritional properties. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

In this work, a Fourier transform mid-infrared spectroscopy (FTIR)-based method was developed for simultaneously quantifying simple sugars and exogenously added fructooligosaccharides (FOS) in strawberry juices preserved for up to 14 d using nonthermal techniques (geraniol and vanillin+ultrasound). The main spectral differences were observed in the 1200 to 900 cm -1 region. The presence of FOS was identified by the typical bands at 1134, 1034, and 935 cm -1 . During storage, a significant decrease of sucrose was concomitant to an increase of glucose and fructose in juices stored without any previous preservation treatment, as determined by high-performance liquid chromatography (HPLC). A principal component analysis was performed on the FTIR spectra corresponding to the different treatments. The groups observed explained more than 94% of the variance and were related to changes in the carbohydrate composition during storage. Then, different partial least square models (PLS) were defined to determine the concentrations of glucose, sucrose, fructose, and those of exogenously added FOS with degrees of polymerization within 3 and 5. The carbohydrates' concentrations determined by HPLC were used as reference method. The models were validated with independent sets of data. The mean of predicted values fitted nicely those obtained by HPLC (correlation and R 2  > 0.97), thus supporting the use of the PLS models to monitor the quality of strawberry juices in unknown samples. In conclusion, FTIR spectroscopy appears as an adequate analytical tool to quick assess whether juice formulations meet specifications in terms of authenticity, contamination and/or deterioration., Practical Application: FTIR spectroscopy provided a method potentially transferable to the food industry when associated with the multivariate analysis. The robust 21 PLS models defined in this work provided reliable tools for the rapid monitoring of juices' authenticity and/or deterioration. In this regard, FTIR associated to multivariate analysis enabled the determination of different sugars in a single measurement without the need of pure sugars as standards. This experimental simplicity supports the use of FTIR at the production line, and also contributes to save time in determining carbohydrates' composition and stability, in an environmentally friendly way., (© 2017 Institute of Food Technologists®.)