Application of ohmic heating to extend shelf life and retain the physicochemical, microbiological, and sensory properties of pulque

Pulque is a Mexican alcoholic, probiotic beverage with shelf life of 3 days. The physicochemical, probiotic, and sensory properties of pulque depend on its content of lactic acid bacteria (LAB) and yeasts. The aim of this study was to apply ohmic heating (OH) in order to extend the shelf life of pulque without altering its properties. Pulque processed by conventional pasteurization (63 °C, 30 min) was used as control. Parameters such as electrical conductivity (0.22 S/m) and optimal pasteurization conditions by OH (65 °C, 5 and 7 min; 70 °C, 3 and 5 min) were determined. Shelf life was evaluated with these parameters during 22 days of storage at 4 ± 1 °C. A higher content of LAB (6.68 and 5.96 log₁₀ CFU/mL) was obtained at 65 °C for 5 and 7 min, respectively, compared with conventional pasteurization (3.54 log₁₀ CFU/mL). After 22 days, physicochemical properties (pH, color, and alcohol content) were stable for both methods of pasteurization. However, the pulque treated with OH had greater sensory acceptance. For the first time, OH was used to process pulque, and results revealed that is an effective technology for extending the shelf life until 22 days, preserving microbiological and physicochemical properties. Microorganisms as surviving the OH treatments were identified as Lactobacillus acidophilus, Lactobacillus kefiri, and Saccharomyces cerevisiae.