Polyphenoloxidase (PPO): Effect, Current Determination and Inhibition Treatments in Fresh-Cut Produce

Abstract

Fresh-cut produce are quite popular among consumers due to their eating ease, high quality and functional content. However, some of the processing steps taking place during minimal processing (such as cutting, peeling, draining, etc.) might speed up decay, e.g., microbial growth, dehydration or browning. When it comes to the latter, polyphenol oxidase (PPO) plays an important role, being the center of many works focused on the understanding of its reaction mechanism and the application of conservative techniques. The aim of this review study was to compare recent research about the effect of PPO on minimally processed fruits and vegetables, trying to understand the way it acts, the measurement of its activity and current treatments, such as modified atmosphere packaging, washing treatments or edible coatings, among others. In conclusion, the combination of conservation techniques (that is, hurdle technology) is vital to guarantee global quality in minimally processed fruits and vegetables, including synergistic effects which will allow the use of mild treatment conditions to decrease PPO activity. However, further research is required to clearly understand PPO inhibition in trendy techniques such as irradiation.

Enzymatic browning in apple products and its inhibition treatments: A comprehensive review

“…Polysaccharide‐based coatings have been studied by prior research to be effective in fresh‐cut preservation; not only exhibiting desirable mechanical properties, and film‐forming ability, but also having selective gas permeability (Pilon et al., 2015). Polysaccharide‐based coatings also showed antimicrobial action (Pilon et al., 2015) that might be beneficial to inhibit enzymatic browning, noting that microbial growth could increase enzymatic browning activity by worsening the cell integrity of apple tissue, provoking cell lysis, and leading to contact between browning enzymes and substrates (Nogales‐Delgado, 2021).…”

“…While for Red Rome, although it exhibited the highest chlorogenic acid content and high quantified phenolic concentration, it browned minimally (low Δ E and Δ C , moderate PPO and POD activity), which might be due to its less maturity than others (Serra et al., 2021). Maturity, selection of cultivars, and preharvest condition (climate, irrigation, rain conditions) may affect the quality and PPO activity of fresh‐cut fruits and vegetables (Nogales‐Delgado, 2021). However, a study found that the maturity did not significantly affect the PPO activity of Elstar, Fuji, and Mellow pulps, but PPO activity decreased significantly along with the maturity (ripeness) of Aori27 pulp, supported by decreased Δ E (after 24 h of storage) and TPC, compared to the immature and half‐mature Aori27 pulp (Holderbaum et al., 2010).…”

“…Nonconventional processing was conducted by recent studies to inhibit the enzymatic browning of apple products (Table 7) without significantly changing the nutritional value and sensory properties resulting due to shorter treatment time and lower treatment temperature than conventional thermal processing. Nonconventional processing also decontaminates food from microbes, noting that higher microbial activity might increase enzymatic browning activity due to reduction of cell integrity (Nogales‐Delgado, 2021). The possible mechanisms of nonconventional processing to inhibit enzymatic browning are summarized in Table 8.…”

Responsive packaging based on imine-chitosan films for extending the shelf-life of refrigerated fresh-cut pineapple

“…Decompartmentalisation and bruising of tissue lead to oxidative reactions such as enzymatic browning reaction and consequent generation of dark pigments (González-Aguilar, Ruiz-Cruz, Cruz-Valenzuela, Rodríguez-Félix, & Wang, 2004). Several authors have also reported the beneficial effect of essential oils delaying browning (Çandır, 2017;Nogales-Delgado, 2021;Zhou, Sun, Zou, Zhou, & Liu, 2021). Over time, chroma values of the samples tended to diminish indicating that the colour intensity of pineapple chunks decreased with storage, this tendency being significantly less accused in fruit that was stored in responsive packages.…”

Control of Enzymatic Browning in Strawberry, Apple, and Pear by Physical Food Preservation Methods: Comparing Ultrasound and High-Pressure Inactivation of Polyphenoloxidase

“…promotes the enzymatic reaction, with subsequent economic losses to the producers or manufacturers. The much appreciated fresh-cut minimally processed fruit and vegetable products are a class of foods also very susceptible to PPO browning [6]. PPO is an endogenous enzyme, which is naturally present in plant tissues, and it has also been referred to as polyphenol oxidase, catechol oxidase, tyrosinase, phenolase, catecholase, and o-diphenol oxidase.…”