The Effect of UV-C Radiation on Key Microorganisms, Detrimental Factors, and Bioactive Compounds of a Fruit and Vegetable Smoothie, and Its Combination with Natural Antimicrobials for Shelf-Life Extension

Abstract

Extending the short shelf-life of natural fruit and vegetable (F&V) beverages while meeting consumer demand for fresh and nutritious products requires innovative preservation methods. This study evaluated the impact of UV-C on key deterioration factors and quality indicators of a mixed F&V smoothie, as well as its combination with natural antimicrobials for shelf-life extension. For this, inactivation and survival of relevant microorganisms were studied, and two equivalent treatments were selected (UVC1: 36 W/m2, 8.45 min; UVC2: 75 W/m2, 3.28 min) to achieve 5 decimal reductions of the most resistant microorganism, which resulted to be Zygosaccharomyces rouxii. In terms of key findings, overall stability and shelf-life studies showed that despite initial reductions in native microflora, both treatments exceeded microbiological limits after approximately three weeks of storage, extending shelf-life by one week compared to the control. Moreover, significant reductions in POD enzymatic activity were showed with values 20-40% lower than the control throughout the storage period. On the other hand, some losses on betalain compounds and, accordingly, a less intense red color were observed. The UVC1 treatment was selected, as it yielded better microbiological results and color preservation, and was combined with the natural antimicrobial natamycin (Na) and/or citric acid (Ci). Through a hurdle technology approach, substantial improvements in microbial quality were achieved, highlighting the great potential of a triple combined treatment (UVC1+Na+Ci), which demonstrated a shelf-life extension of at least 49 days under refrigeration, keeping all microbial counts below the detection limit.