Combined treatments of benzoic acid and pasteurization factors for controlling microbiological and physico-chemical quality in asparagus stalk juice using response surface methodology

Asparagus stalks are classified as agricultural by-products owing to their antioxidant and phytochemical properties. In this study, it was used as a raw material for asparagus stalk juice, a new value-added product. Response Surface Methodology (RSM) equations were generated using the Box-Behnken design with three replications, while pasteurization temperature (65 degrees C, 75 degrees C, and 85 degrees C), pasteurization time (15, 20, and 25 min), and benzoic acid (0, 0.5, and 1 mg/mL) were used as the independent variables. All RSM models indicated that total viable count, CIE color, pH, total phenolic content, and DPPH scavenging activity were the main parameters affecting the physicochemical characteristics and microbiological quality of asparagus stalk juice products. The normal % probability and externally studentized residuals of all RSMs demonstrated that their predictive modelling was a promising method for quality control and assurance during asparagus stalk juice pasteurization using benzoic acid as a preservative agent. Based on the experimental data, the optimal conditions for asparagus stalk juice were obtained using 1 mg/mL benzoic acid at 75 degrees C for 25 min, and a pH value of approximately 3.83, which corresponded to good microbiological quality and antioxidant activity. This scientific evidence could be used as a guideline for developing quality control and quality assurance systems for asparagus stalk juice and/or vegetable juice-based products.