Quality-Related Enzymes in Plant-Based Products: Effects of Novel Food-Processing Technologies Part 3: Ultrasonic Processing

Abstract

High-power ultrasound is a versatile technology which can potentially be used in many food processing applications including food preservation. This is part 2 of a series of review articles dealing with the effectiveness of nonthermal food processing technologies in food preservation focusing on their effect on enzymes. Typically, ultrasound treatment alone does not efficiently cause microbial or enzyme inactivation sufficient for food preservation. However, combined with mild heat with or without elevated pressure (P ≤ 500 kPa), ultrasound can effectively inactivate enzymes and microorganisms. Synergistic effects between ultrasound and mild heat have been reported for the inactivation of both enzymes and microorganisms. The application of ultrasound has been shown to enhance the rate of inactivation of quality degrading enzymes including pectin methylesterase (PME), polygalacturonase (PG), peroxidase (POD), polyphenol oxidase (PPO), and lipoxygenase (LOX) at mild temperature by up to 400 times. Moreover, ultrasound enables the inactivation of relatively heat-resistant enzymes such as tomato PG1 and thermostable orange PME at mild temperature conditions. The extent to which ultrasound enhances the inactivation rate depends on the type of enzyme, the medium in which the enzyme is suspended, and the processing condition including frequency, ultrasonic intensity, temperature, and pressure. The physical and chemical effects of cavitation are considered to be responsible for the ultrasound-induced inactivation of enzymes, although the dominant mechanism depends on the structure of the enzyme.

Thermal and non‐thermal processing technologies on intrinsic and extrinsic quality factors of tomato products: A review

“…However, there is no evidence in literature to show that sonication (together with heat or pressure) causes higher quality degradation than an equivalent thermal process (Terefe, Buckow, & Versteeg, 2015). In general, when US is applied at suitable power density, it has great potential in inhibiting decay, maintaining flavor and nutritional quality of tomato products.…”

Gene-Based Developments in Improving Quality of Tomato: Focus on Firmness, Shelf Life, and Pre- and Post-Harvest Stress Adaptations

“…When considering the post-harvest stability of horticulture crops, the attribute of texture holds significant importance. Multiple enzymes including polygalacturonase (PG), pectin methylesterase (PME), endo-b-(1,4)-glucanase (EG), β-galactosidase (β-gal), and expansion (EXP), as well as N-glycoprotein-modifying enzymes like α-mannosidase (α-Man) and β-D-N-acetylhexosaminidase (β-Hex), play crucial roles in determining the degree of firmness and softening processes in various plants [14,15]. Several studies have highlighted the suppression of key gene expressions in strawberries and tomatoes.…”

Application of High-Power Ultrasound in the Food Industry

“…However, when combined with heat (thermo-sonication, TS), pressure (MS), or heat and pressure (MTS), processing times can also be reduced. For example, the application of MTS is able to reduce the heat resistance of enzymes by 2-400-fold such as alkaline phosphatase, polyphenol oxidase, peroxidase, lipase, lipoxygenase, pectin methylesterase, and polygalacturonase compared to heat treatments applied at the same temperature [32,[39][40][41][42][43][44][45]. As an example, Figure 3 shows the activity reduction of pectin methylesterase of tomato juice treated by heat, MS, and MTS treatments at 62.5°C and 1 minute.…”