Glycine

Glycine, serine, and γ-aminobutyric acid are effective scavengers of reactive carbonyl species and should inhibit the formation of advanced glycation end products (AGEs). However, here we found that amino acids unexpectedly increased the intensity of fluorescent AGEs in biscuits. This study aimed to elucidate these contradictory findings and highlight concerns regarding the determination of fluorescent AGEs in foods. In gliadin-methylglyoxal (MGO) glycation model, amino acids were found to induce formaldehyde formation from MGO. Thereafter, formaldehyde and MGO reacted with the amino acids to generate imidazole salts. The imidazole salts exhibited broad fluorescence range, overlapping with the fluorescence range used to determine fluorescent AGEs in foods, thus resulting in an apparent increase in fluorescent AGEs content after amino acid addition. Since amino acids are ubiquitous in food materials, the formation of imidazole salts during food processing may result in an overestimation of fluorescent AGEs in foods.

The study prepared an edible packaging material for peony seed oil by adding natural antioxidant vanillin to a microbial Levan composite film. The presence of highly branched Levan, containing polyhydroxyl groups, significantly enhanced the maximum tension (26.57 N), tensile strength (36.31 MPa), and elongation at break (42.15 %) of the Aga/Lev film. The values were 9.84-fold, 5.74-fold, and 1.11-fold higher than those of Aga films, respectively. Furthermore, SEM and FTIR analysis revealed that Levan increased the intermolecular force of the vanillin composite film (Aga/Lev/Gly/Van), forming a dense gel network with a Schiff base reaction occurring between vanillin and glycine. The addition of vanillin and glycine slightly lowered the transparency of the film but enhanced the ultra violet (UV)-blocking with 100 % UV-region and 91 % visible region light screening. The Aga/Lev/Gly/Van films showed strong antioxidant efficacy with 91.85 % ABTS and 44.33 % DPPH radical scavenging potential. The electrical conductivity, P-anisidine value, thiobarbituric acid value, and fatty acid distribution of peony seed oil samples were analyzed after accelerated storage. The Aga/Lev/Gly/Van group had a significantly higher retention rate (95.65 %) for total conjugated fatty acids compared to the control group (84.17 %). The utilization of Aga/Lev/Gly/Van film packaging effectively extended the shelf life of peony seed oil and retarded the degradation of unsaturated fatty acids in the oil. Therefore, Levan composite films incorporating vanillin can be used as sustainable packaging materials to minimize the oxidation of susceptible foods.