Pulsed Light: Challenges of a Non-Thermal Sanitation Technology in the Winemaking Industry

Abstract

Pulsed light is an emerging non-thermal technology viable for foodstuff sanitation. The sanitation is produced through the use of high energy pulses during ultra-short periods of time (ns to µs). The pulsed light induces irreversible damages at the DNA level with the formation of pyrimidine dimers, but also produces photo-thermal and photo-physical effects on the microbial membranes that lead to a reduction in the microbial populations. The reduction caused in the microbial populations can reach several fold, up to 4 log CFU/mL decrement. A slight increase of 3 to 4 °C in temperature is observed in treated food; nonetheless, this increase does not modify either the nutritional properties of the product or its sensory profile. The advantages of using pulsed light could be used to a greater extent in the winemaking industry. Experimental trials have shown a positive effect of reducing native yeast and bacteria in grapes to populations below 1–2 log CFU/mL. In this way, pulsed light, a non-thermal technology currently available for the sanitation of foodstuffs, is an alternative for the reduction in native microbiota and the later control of the fermentative process in winemaking. This certainly would allow the use of fermentation biotechnologies such as the use of non-Saccharomyces yeasts in mixed and sequential fermentations to preserve freshness in wines through the production of aroma volatile compounds and organic acids, and the production of wines with less utilization of SO2 in accordance with the consumers’ demand in the market.

Keywords

• antimicrobial
• food technology
• non-<i>Saccharomyces</i>
• enzymatic activity
• wine quality