Green Tea Polyphenols Decrease Strecker Aldehydes and Bind to Proteins in Lactose-Hydrolyzed UHT Milk

Abstract

The effect of epigallocatechin gallate enriched green tea extract (GTE) on flavor, Maillard reactions and protein modifications in lactose-hydrolyzed (LH) ultrahigh temperature (UHT) processed milk was examined during storage at 40 °C for up to 42 days. Addition of GTE inhibited the formation of Strecker aldehydes by up to 95% compared to control milk, and the effect was similar when GTE was added either before or after UHT treatment. Release of free amino acids, caused by proteolysis, during storage was also decreased in GTE-added milk either before or after UHT treatment compared to control milk. Binding of polyphenols to milk proteins was observed in both fresh and stored milk samples. The inhibition of Strecker aldehyde formation by GTE may be explained by two different mechanisms; inhibition of proteolysis during storage by GTE or binding of amino acids and proteins to the GTE polyphenols.

Application of PTR‐TOF‐MS for the quality assessment of lactose‐free milk: Effect of storage time and employment of different lactase preparations

“…Benzaldehyde can be considered a thermally induced compound in milk 38 . The formation may occur alongside Maillard reaction starting from phenylalanine 6 . The mechanism involves the conversion of the amino acid to phenylacetaldehyde via Strecker degradation and subsequent oxidation to benzaldehyde 39 .…”

“…Focusing on LFM, manufacturing is not trivial, and it poses additional challenges. For example, even though heating the milk at ultrahigh temperature (UHT) guarantees a prolonged shelf life 5 , the presence of free glucose and galactose produced by lactose hydrolysis renders the product susceptible to Maillard reaction 6 . Moreover, most UHT LFMs are produced by adding free soluble β‐1,4‐galactosidase (lactase) to the milk 3 .…”

“…Together with other analysis, the study demonstrated stronger occurrence of Maillard reaction in LFM. As a solution, the same research group published an article proposing the addition of green tea extract (GTE) to UHT LFM to inhibit the proceeding of the reaction 6 . They studied the volatiles profile of UHT LFM added with GTE again by DHS GC‐MS, and a significant decrease of specific VOCs was demonstrated.…”

Evaluation of the effect of berry extracts on carboxymethyllysine and lysine in ultra-high temperature treated milk

“…Nevertheless, these experiments were studying the effect of the extracts on simple model systems. On the other hand, green tea polyphenols decreased Strecker aldehydes in lactosehydrolysed UHT milk (Jansson et al, 2017) but their effect on CML was not assessed.…”

Characterisation of protein-polyphenol interactions in beer during forced aging

“…In beer, potential pathways for their formation have been suggested ( 5 ) , but the exact nature of these covalent bonds has not yet been clarified. In contrast, covalent protein‐polyphenol bonds have been investigated in other foods and beverages, such as meat and dairy products ( 12–15 ) . The key difference is that these animal derived products do not naturally contain polyphenols, however they may be added during production to protect against oxidation or Maillard reactions (i.e.…”