Use of Ultra-High Pressure Homogenization processing in winemaking:Control of microbial populations in grape musts and effects in sensory quality

Abstract

Ultra-High Pressure Homogenization (UHPH) is a fast and efficient technique that can sterilizefluid foods at lowtemperatures or even under cooling conditions. A white must (Vitis viniferaL.) was processed at 300 MPa (inlettemperature 20 °C, in-valve temperature 98 °C, outlet temperature 25 °C, and time in valve 0.02 s) and theirperformance was compared with two untreated controls, a must that underwent a spontaneous fermentation(without SO2addition) and another must that was sulfited with 35 mg/L of total SO2and inoculated with thesameSaccharomyces cerevisiaeyeast as the UHPH-treated must. UHPH treatment led to the total elimination ofgrape microorganisms considering an initial population of 1 × 106CFU/mL in average of wild yeasts and fungiin must, and approximately 7 × 103CFU/mL of background bacteria. In a parallel assay, UHPH-processed mustwithout yeast inoculation showed absence of fermentation for eight days at 18 °C. The musts treated with UHPHshowed a lighter appearance (10%) before fermentation compared to the control. The triangular test verified theexistence of sensory differences between the wines obtained and the preference tests showed that the judgesfound the wine obtained from the UHPH-treated must more fruity (3.5/5 compared with 1.5–2 in controls) andwith better aroma.Industrial relevance:UHPH is an interesting way to process the must before fermentation allowing the reductionof sulfite addition while controlling wild and spoilage microorganisms.