Effects and mechanism of free amino acids on browning in the processing of black garlic

Abstract

BACKGROUND Black garlic is produced by heating raw garlic at a high temperature for a long time without any additives. The thermal processing induces many chemical reactions, such as the Maillard reaction, which causes the color change from white to dark brown. Garlic contains a variety of amino acids, and the effect of each amino acid on browning is not fully understood. This work investigated the effect and mechanism of free amino acids on the browning of black garlic using model solutions containing garlic neutral polysaccharide, hydrolyzed garlic neutral polysaccharide, fructose, and free amino acids. RESULTS A significant increase in reducing sugar was detected when garlic neutral polysaccharide was heated with glycine. The browning intensity of garlic neutral polysaccharide‐glycine model solution was obviously higher after heating at 80 °C compared with that of garlic neutral polysaccharide solution. The model solution containing histidine had the greatest browning degree. The histidine model has a stable pH value, and almost no 5‐hydroxymethylfurfural (5‐HMF) was detected. CONCLUSION Amino acid can promote the breaking of the garlic neutral polysaccharide chain and can react with the fructose generated to form browning. Histidine has the greatest effect on the browning, because histidine could eliminate the inhibiting effect of organic acid on Maillard reaction due to the buffer ability, and histidine had high reactivity in the late stage of Maillard reaction. © 2019 Society of Chemical Industry

Maillard Reaction Intermediates and Related Phytochemicals in Black Garlic Determined by EPR and HPLC Analyses

“…Note that the soft state of the black garlic after 28 days made it difficult to handle, and the EPR intensity was very high at 28 days ( Figure 3 and Figure 4 ). Although Amadori and Heyns contents as the indication of the Maillard reaction were reported [ 6 , 8 ], a positive correlation between EPR intermediate and melanoidin suggests that EPR intensity may be a good index of garlic browning.…”

“…Moreover, human taste-active compounds of the Maillard reaction products in roasted garlic were reported [ 7 ]. The effect of browning due to sugar and amino acid reaction during the processing of black garlic was also reported [ 8 , 9 ]. Melanoidin and other brown polymer compounds produced from the Maillard reaction give food a characteristic dark brown color.…”

Effects of Anaerobic Fermentation on Black Garlic Extract by Lactobacillus: Changes in Flavor and Functional Components

“…A possible reason is that the reducing sugars may be the preferred carbon source compared with sources such as polysaccharides. Therefore, the reducing sugars would be used first during the early fermentation stages until they are relatively low in abundance, at which point the probiotics may begin to consume other carbon sources (e.g., polysaccharides), which could produce high levels of reducing sugars (25,32,33).…”

Ethylene and its inhibitors affect the quality of processed sweet potatoes

“…This process is initiated when the carbonyl group of the reducing sugar reacts with an amino group of free amino acids. The initial products of the reaction are N-glycosylamines or N-fructosylamines, which give rise to intermediate products and final heterocyclization and polymerization (Liu et al, 2019). Unlike potatoes, sweet potatoes contain low asparagine levels and high reducing sugar levels, therefore, asparagine is probably a limiting factor in the acrylamide formation in fried sweet potato chips (Truong et al, 2014).…”