Maillard reaction products-based encapsulant system formed between chitosan and corn syrup solids: Influence of solution pH on formation kinetic and antioxidant activity

Structural and functional modifications of quinoa protein via hyaluronic acid-induced Maillard reaction

In recent years, quinoa protein (QP) has attracted attention for its balanced amino acids composition, but its limited techno-functional properties continue to pose challenges for its utilization. Non-enzymatic Maillard glycation is considered as a promising strategy to expand the utilization of plant proteins in food processing due to its cost-effectiveness, spontaneous nature, and the lack of need for additives to initiate the reaction. Furthermore, the use of hyaluronic acid (HA) as an ingredient in food products is becoming increasingly accepted and popular. Therefore, the present study aims to prepare QP-HA glyconjugates by wet heating and to investigate the effects of sugar/protein ratios and reaction times on the structural features and functional properties of QP. The results showed that heating time and sugar/protein concentration ratio obviously affected the degree of grafting, structure and hydrophobicity of the conjugates. The random coil content of QP-HA increased significantly, resulting in a more flexible structure after Maillard glycation. After 3 h of glycation reaction, the QP-HA conjugates showed better emulsification, solubility, thermal stability and antioxidant activity compared to QP. Accordingly, these results indicate that polysaccharide-induced Maillard reaction is a potentially attractive approach for selective functionality enhancement and nutraceutical development of QP, which provides a new way to expand the application range of QP.

Chemical composition and antioxidant activity of Polygonatum kingianum processed by the traditional method of "Nine Cycles of Steaming and Sun-Drying"

Polygonatum kingianum Coll. et (Hemsl) is a famous Chinese traditional food and medicine analogous plant. The rhizome of P. kingianum showed a decrease in levels of alkaloids, amino acids and derivatives, terpenoids, and an increase in organic acid and saccharides when it was processed by the traditional method of "Nine Cycles of Steaming and Sun-Drying". The relative content of 341 metabolites were increased (fold change, FC > 2; variable importance in projection, VIP > 1 and P-value, P < 0.05); while 456 metabolites were decreased (FC < 0.5, VIP > 1, and P < 0.05). The changes in chemical components result in a decrease in numb taste and an increase in sweetness. The increased antioxidant activity was observed in the processed samples. Together, this work has advanced the mechanism of reducing numb taste and enhancing antioxidant activity in the resource plants, such as P. kingianum, processed by the traditional method.

Effects of Reducing Sugars on Colour, Amino Acids, and Volatile Flavour Compounds in Thermally Treated Minced Chicken Carcass Hydrolysate

This study investigated the changes in colour, amino acids, and volatile flavour compounds in the enzymatic hydrolysates of chicken carcasses containing different types and amounts of reducing sugars (xylose, arabinose, glucose, and fructose), so as to develop a chicken-based flavouring agent. Before heat treatment at 100 °C for 60 min, the chosen reducing sugars were separately added to the chicken carcass hydrolysate at its natural pH. Pentoses decreased pH more significantly than hexoses in the chicken carcass hydrolysate. The browning degree followed the pattern of pH decline, as pentoses caused more intense browning than hexoses, with xylose dosage having the greatest effect on the colour changes (ΔE). Fructose addition notably reduced free amino acids (FAAs) and cystine contents. Furthermore, phenylalanine decreased with increasing dosages of arabinose, xylose, and fructose. Glutamic acid content decreased significantly with fructose addition but showed insignificant changes with xylose. At the same dosage, the addition of pentoses resulted in the production of more sulphur-containing volatile compounds like methional, 2-[(methylthio) methyl] furan, and dimethyl disulphide than hexoses. Methional and furfural, which provide a roasted, savoury flavour, were produced by adding more xylose. Heat treatment with xylose also removed hexanal, the main off-odourant.

The effect of Maillard reaction on flavour development of protein hydrolysates from cheese

This study aims to explore the effect of the Maillard reaction (MR) on flavour development of cheese protein hydrolysates. In addition, the effects of proteolysis, lipolysis, and the degreasing process on the MR have been explored. Cheese protein hydrolysates subjected to different treatments were heated with glucose and xylose, and their amino reactant components, colour parameters, and volatile compounds were determined. The results showed that the MR significantly affected the content of free amino acids, peptides, and volatile flavours of cheese protein hydrolysates. Peptides below 1500 Da and most of the free amino acids were the important amino reactants during the MR. 3-Ethyl-2,5-dimethylpyrazine, 2,5-dimethylpyrazine, 2-undecanone and 2-heptanone were the key volatile components of the MR products. The results also indicated that N-terminal amino acids of the peptide chain were easier to be reacted than C-terminal amino acids and thus produce a pyrazine-like flavour in the MR.

Ultrasound-assisted formation of chitosan-glucose Maillard reaction products to fabricate nanoparticles with enhanced antioxidant activity

The influence of ultrasonic processing parameters including reaction temperature (60, 70 and 80 °C), time (0, 15, 30, 45 and 60 min) and amplitude (70, 85 and 100%) on the formation and antioxidant activity of Maillard reaction products (MRPs) in a solution of chitosan and glucose (1.5 wt% at mass ratio of 1:1) was investigated. Selected chitosan-glucose MRPs were further studied to determine the effects of solution pH on the fabrication of antioxidative nanoparticles by ionic crosslinking with sodium tripolyphosphate. Results from FT-IR analysis, zeta-potential determination and color measurement indicated that chitosan-glucose MRPs with improved antioxidant activity were successfully produced using an ultrasound-assisted process. The highest antioxidant activity of MRPs was observed at the reaction temperature, time and amplitude of 80 °C, 60 min and 70%, respectively, with ∼ 34.5 and ∼20.2 μg Trolox mL^-1 for DPPH scavenging activity and reducing power, respectively. The pH of both MRPs and tripolyphosphate solutions significantly influenced the fabrication and characteristics of the nanoparticles. Using chitosan-glucose MRPs and tripolyphosphate solution at pH 4.0 generated nanoparticles with enhanced antioxidant activity (∼1.6 and ∼ 1.2 μg Trolox mg^-1 for reducing power and DPPH scavenging activity, respectively) with the highest percentage yield (∼59%), intermediate particle size (∼447 nm) and zeta-potential ∼ 19.6 mV. These results present innovative findings for the fabrication of chitosan-based nanoparticles with enhanced antioxidant activity by pre-conjugation with glucose via the Maillard reaction aided by ultrasonic processing.

Chaste honey in long term-storage: Occurrence and accumulation of Maillard reaction products, and safety assessment

Honey, a natural sweetener that can be stored long-term, is prone to Maillard reactions. Maillard reaction products (MRPs), such as 5-hydroxymethylfurfural (5-HMF), α-dicarbonyl compounds (α-DCs), and advanced glycation end products (AGEs), negatively affect human health. We analyzed MRP accumulation in chaste honey over four years. In the first year, α-DCs were dominant with total contents of 509.7 mg/kg. In the second year, Amadori compounds increased, accounting for the largest percentage. Their formation at the initial stage showed inhibition of the Maillard reaction over time. AGE contents were approximately 1.00 mg/kg over four years, which is negligible compared to other foods. Increased 5-HMF was significantly correlated with storage time (p < 0.01), making it a suitable indicator of honey quality. Due to the lack of MRP risk assessments, we compared our findings with daily intake of MRPs from other foods, and the levels of MRPs in honey over four years are acceptable.

Understanding the impact of pectin physicochemical variation on browning of simulated Maillard reaction system in thermal and storage processing

Maillard reaction browning is one of the quality deterioration in dried fruit products, but how pectin affects Maillard reaction in the fruit drying and storage process is not clear. This study aimed at investigating the mechanism of pectin variation impact on the browning of Maillard reaction by using simulated system (l-lysine, d-fructose and pectin) in thermal (60 °C and 90 °C for 8 h) and storage (37 °C for 14 days) process. Results showed that apple pectin (AP) and sugar beet pectin (SP) significantly enhanced the browning index (BI) of the Maillard reaction system by 0.01 to 134.51 in the thermal and storage processes, respectively, which were methylation degree of pectin-dependent. The pectin depolymerization product participated Maillard reaction by reacting with l-lysine, and increasing the 5-hydroxymethyl furfural (5-HMF) content (1.25-11.41-fold) and Abs_420nm (0.01-0.09). It also produced a new product (m/z 225.1245), which finally increased browning level of the system.

Acid-induced Poria cocos alkali-soluble polysaccharide hydrogel: Gelation behaviour, characteristics, and potential application in drug delivery

Poria cocos alkali-soluble polysaccharide (PCAP), a water-insoluble β-glucan, is the main component of the total dried sclerotia of Poria cocos. However, its gelation behaviour and properties have yet to be comprehensively studied. In this study, an acid-induced physical hydrogel based on natural PCAP is fabricated. The acid-induced gelation in PCAP is explored with respect to the pH and polysaccharide concentration. PCAP hydrogels are formed in the pH range of 0.3-10.5, and the lowest gelation concentration is 0.4 wt%. Furthermore, dynamic rheological, fluorescence, and cyclic voltammetry measurements are performed to elucidate the gelation mechanism. The results reveal that hydrogen bonds and hydrophobic interactions play a dominant role in gel formation. Subsequently, the properties of the PCAP hydrogels are investigated using rheological measurements, scanning electron microscopy, gravimetric analysis, free radical scavenging, MTT assays, and enzyme-linked immunosorbent assays. The PCAP hydrogels exhibit a porous network structure and cytocompatibility, in addition to good viscoelastic, thixotropic, water-holding, swelling, antioxidant, and anti-inflammatory activities. Furthermore, using rhein as a model drug for encapsulation, it is demonstrated that its cumulative release behaviour from the PCAP hydrogel is pH dependent. These results indicate the potential of PCAP hydrogels for application in biological medicine and drug delivery.