Thermal kinetics of enzyme inactivation, color changes, and allicin degradation of garlic under blanching treatments

Abstract

Blanching is a feasible and effective method widely applied to prevent greening in garlic puree. However, this processing may cause the physical and chemical changes in garlic puree. Therefore, an investigation was carried out to systematically explore the effects of hot water blanching on enzyme inactivation (alliinase and γ‐glutamyl transpeptidase, GGT), discoloration, allicin degradation, and antioxidant capacity of garlic puree. The results showed that the inactivation of alliinase and GGT was strongly dependent on blanching temperature and time. Garlic puree turned into white when blanched at 80°C for 5 min or at 90°C for 4 min, with a* value of −3.24 ± 0.11, −2.80 ± 0.43, respectively. The inactivation kinetics of alliinase and GGT followed a first‐order reaction, as well as the kinetic of green discoloration. However, allicin content was dropped by 71, 80, and 85% after blanching for 5 min at 70, 80, and 90°C, respectively. A decline in the antioxidant capacity of garlic treated by blanching was also observed. The current findings indicated that blanching could contribute to inhabit garlic greening but had negative effects on the nutritional ingredients of garlic puree. Practical applications Garlic is prone to greening when processed into garlic puree, garlic juice and other products. The occurrence of greening seriously hindered the further processing of garlic. Blanching is an effective and feasible method to prevent greening in garlic puree. In this study, the effects of blanching on enzyme inactivation, color changes, allicin degradation and antioxidant capacity of garlic puree were studied. This study provides a theoretical basis for the deep processing of garlic.

Screening of gamma-aminobutyric acid-producing lactic acid bacteria and the characteristic of glutamate decarboxylase from Levilactobacillus brevis F109-MD3 isolated from kimchi

“…The D value is the decimal reduction time, and the Z value represents the temperature range that resulted in a 10-fold change in the D values. They are important parameters commonly used in the characterization of enzyme stability (Beluhan et al, 2020;Huang et al, 2019;Wehaidy et al, 2018). To our knowledge, this is the first time to determine the Z value of GAD from LAB.…”

Chemometric optimisation of pressurised liquid extraction for the determination of alliin and S‐allyl‐cysteine in giant garlic (Allium ampeloprasum L.) by liquid chromatography tandem mass spectrometry

“…Considering the individual optimal zones observed on response surface plots (Figure 2) and the equipment's routine operational conditions, a simple pressurised liquid extraction condition for both types of samples (with or without blanching) was established using an ethanol percentage of 75% v/v and an extraction temperature of 100 C. Applying these optimised conditions, the experimental yield values were similar to the predicted ones and, as expected, significantly higher alliin yield values (p = 0.0141) were observed in blanched garlic (Table 2) due to inactivation of alliinase enzymes. 27 This increase in extraction yields reached near to 40% using blanching process. Therefore, this technological step seems to be relevant for an adequate extraction and determination of alliin (and its congeners) in garlic.…”

“…90 C) in selfsealing plastic bags (to avoid the contact with water) to inactivate alliinase and γ-glutamyl transpeptidase enzymes. 27 Both types of samples were then frozen for 48 h at −24 C, sliced, and freeze-dried for 24 h at −55 C, using an Alpha 1-2 LD plus freeze dryer (Martin Christ, Osterode am Harz, Germany). Dried garlic samples were ground and homogenised using an A11 basic analytical mill (IKA, Staufen, Germany).…”

Garlic greening: Pigments biosynthesis and control strategies

“…This treatment involves heating at 70-100°C for 1-30 min with hot water or microwaves and is applied to processed vegetables to achieve enzymatic inactivation and reduce microbial contamination. Blanching conditions are poorly tolerated by both GGT and alliinase, whose activity rapidly drops after 10 min at 70°C (Huang et al, 2019;Yin et al, 2009), whereas complete inactivation was reported after 30 min at 70°C for GGT and after 15 min at 90°C for alliinase (Mochizuki et al, 1988;Rejano et al, 1997). However, heat treatments also cause a decrease in the contents of allicin and other antioxidant molecules, leading to impoverishment in the bioactive properties of garlic.…”

“…However, heat treatments also cause a decrease in the contents of allicin and other antioxidant molecules, leading to impoverishment in the bioactive properties of garlic. A recent study calculated the kinetics of GGT and alliinase inactivation along with that of decrease in concentration and antioxidant activity of allicin (Huang et al, 2019). Following a holistic approach, these authors proposed a blanching treatment of 4 min at 90°C, which seemed to be a good compromise to obtain an effective enzyme inactivation and limited losses of allicin and other valuable compounds.…”