Effects of thermal and non-thermal processing treatments on fatty acids and free amino acids of grape juice

Common thermal and pulsed electric field (PEF) treatments have been evaluated to assess their effect on fatty acids and free amino acids contents of Parellada grape juice. These compounds have great importance in winemaking as nutritive compounds for yeasts growth. The effect of thermal and PEF treatments has also been determined on several physicochemical properties and a population of inoculated Saccharomyces cerevisiae. Both technologies reduced the population of the spoilage microorganism inoculated in grape juice. No viable cells were observed after thermal processing of grape juice whereas PEF treatment achieved four logarithmic reductions of the microbial viability. No significant changes were noticed on physicochemical properties measured such as reducing sugar content, total acidity and pH. Neither thermal nor PEF treatments modified the total content of fatty acids and free amino acids of Parellada grape juice. However, the concentration of lauric acid diminished after PEF processing and the concentration of some amino acids varied after both treatments.