The potential of nonthermal techniques to achieve enzyme inactivation in fruit products

The inherent acidity of fruit products acts as a hurdle to microbial growth; however, enzymatic stability is still a concern for its shelf-life. In the last two decades, the fruit processing industry has shifted to nonthermal treatments to fulfill the demand for microbial and enzymatic stability. Nevertheless, while deciding the nonthermal process intensity for a fruit product, microbial safety is targeted along with maximum retention of phytochemicals to fulfill the demands of both manufacturers and consumers. However, retailers demand a stable fresh-like product devoid of enzymatic spoilage. This review briefs about enzymatic spoilage in fruit products and the mechanism of nonthermal inactivation of enzymes such as polyphenoloxidase and pectinmethylesterase. The extent of enzyme inactivation in fruit products by various nonthermal treatments with or without any added hurdle is discussed. The hurdles include coupling a nonthermal treatment with other nonthermal treatments, mild thermal treatment, antimicrobials, coatings, etc. The intensity of a nonthermal treatment may not often be sufficient to achieve a complete inactivation of spoilage enzymes. The product matrix, viz., fruit pieces, purees, or juice, plays a vital role in the extent of enzyme inactivation. Hurdle technology of nonthermal treatment with mild heat treatment (40–70 °C) is better for achieving adequate inactivation. Nevertheless, there is enough evidence that the enzyme might regain its activity during storage. To satisfy the demands of all the stakeholders, the nonthermal process design for a fruit product should emphasize achieving enzyme inactivation while ensuring microbial safety and quality retention. • The review briefs about the enzymatic spoilage in fruits products. • The nonthermal inactivation of spoilage enzymes in fruit products is discussed. • Limited studies exist on the stability of those spoilage enzymes during storage. • The enzyme might regain its activity during storage after the treatment. • The nonthermal treatment should achieve enzymatic stability and quality retention.