Multiple response surface optimization for effects of processing parameters on physicochemical and bioactive properties of apple juice inoculated with Zygosaccharomyces rouxii and Zygosaccharomyces bailii

• Response surface methodology was used to model growth of Z. rouxii and Z. bailii.
• Mint essential oil was investigated in a real food environment like apple juice.
• Mint essential oil had a remarkable antifungal effect on Z. rouxii and Z. bailii.
• When mint essential oil was combined with sodium benzoate lower inactivation was observed.

In this study, response surface methodology was used to evaluate effect of some processing parameters; namely, sodium benzoate (SB, 0–0.1%), mint essential oil (MEO, 0–1000 ppm), storage temperature (4–20 °C) and time (1–41 days) on physicochemical and bioactive properties of apple juice inoculated with Zygosaccharomyces rouxii and Zygosaccharomyces bailii. A multiple-response optimization was conducted to determine simultaneous effects of the processing variables that maximize and minimize the characterized properties of apple juice. The results showed that MEO had a remarkable anti-yeast effect on Z. rouxii and Z. bailii, which revealed that it had a comparable effect with that of SB in terms of anti-yeast activity. In addition, synergistic/antagonistic effects were investigated; however, it was revealed that there were antagonistic effects between SB and MEO in terms of bioactive properties. The effect of MEO on the bioactive properties was more pronounced in apple juice samples inoculated with Z. bailii than in those inoculated with Z. rouxii. Multiple-response optimization analysis revealed that minimum yeast count (YC) values (0.017 or 0.271 log cfu/ml) would occur at storage time = 15.78 or 15.72 days, storage temperature = 9.28 or 7.47 °C, SB concentration = 0.00% and MEO concentration = 1,000 ppm.