Process optimization and the relationship between the reaction degree and the antioxidant activity of Maillard reaction products of chicken liver protein hydrolysates

Unlocking the potential of chicken liver byproducts: Identification of antioxidant peptides through in silico approaches and anti-aging effects of a selected peptide in Caenorhabditis elegans

Chicken meat processing generates a substantial number of byproducts, which are either underutilized or improperly disposed. In this study, we employed in silico approaches to identify antioxidant peptides in chicken liver byproducts. Notably, the peptide WYR exhibited remarkable 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity with an IC50 of 0.13 ± 0.01 mg/mL and demonstrated stability under various conditions, including thermal, pH, NaCl, and simulated gastrointestinal digestion. Molecular docking analysis revealed significant hydrogen bonding interactions, while molecular dynamics showed differential stability with ABTS and 2,2-Diphenyl-1-picrylhydrazyl (DPPH). WYR exhibited improved stress resistance, decreased levels of reactive oxygen species (ROS), elevated the activities of superoxide dismutase (SOD) and catalase (CAT), and modulated the expression of crucial genes through the insulin/insulin-like growth factor (IIS) signaling pathway, mitogen-activated protein kinase (MAPK), and heat shock transcription factor-1 (HSF-1) pathways. These effects collectively contributed to the extension of Caenorhabditis elegans' lifespan. This study not only provides an effective method for antioxidant peptide analysis but also highlights the potential for enhancing the utilization of poultry byproducts.

Controlled Selective Formation of Amadori Compounds from α/ε Mono- or Di-glycation of Lysine with Xylose

Three Amadori rearrangement products (Xyl-α-Lys-ARP, Xyl-ε-Lys-ARP, and diXyl-α,ε-Lys-ARP) were observed in the xylose-lysine (Xyl-Lys) Maillard reaction model. They were separated and characterized by liquid chromatography with tandem mass spectrometry and NMR. The crucial roles of reaction temperature, pH, molar ratio of Xyl to Lys, and reaction time in the formation of different Xyl-Lys-ARPs were investigated. The proportion of Xyl-α-Lys-ARP among all Xyl-Lys-ARPs was increased to 48.41% (its concentration was 25.31 μmol/mL) after the reaction at pH = 5.5 and a molar ratio of 3:1 (Xyl: Lys) for 9 min, while only Xyl-ε-Lys-ARP was generated at a higher pH (7.5) and a lower molar ratio of 1:5. Moreover, the much higher activation energy (84.08 kJ/mol) of diXyl-α,ε-Lys-ARP than Xyl-α-Lys-ARP (34.19 kJ/mol) and Xyl-ε-Lys-ARP (32.32 kJ/mol) indicated a pronounced promoting effect on diXyl-α,ε-Lys-ARP formation by high temperatures. A complete conversion from Xyl-α-Lys-ARP and Xyl-ε-Lys-ARP to diXyl-α,ε-Lys-ARP was achieved through the reaction time prolongation and Xyl concentration increase at a higher temperature; the concentration of diXyl-α,ε-Lys-ARP was 39.05 μmol/mL at a molar ratio of 5:1 for 40 min. Accordingly, the selective preparation of Xyl-α-Lys-ARP, Xyl-ε-Lys-ARP, and diXyl-α,ε-Lys-ARP could be achieved through adjusting the Xyl-Lys ratio, pH, and reaction time.

Preparation of modified Jiuzao glutelin isolate with carboxymethyl chitosan by ultrasound-stirring assisted Maillard reaction and its protective effect of loading resveratrol/quercetin in nano-emulsion

Jiuzao glutelin isolate (JGI) was reported to possess interface and functional properties. To enhance the stability and properties of JGI, conjugation between JGI and carboxymethyl chitosan (CTS) through ultrasound-stirring assisted Maillard reaction (UTSA-MR) was investigated and optimized. The changes of molecular distribution, secondary structure, morphology, and amino acid composition of JGI were detected after conjugation with CTS. The solubility, foaming property and stability, viscosity, and thermal stability of four conjugates (CTS-JGI, with weight ratios of 0.5:1, 1:1, 2:1, and 4:1) were significantly increased compared to native JGI. Under the optimal glycation, the conjugate (CTS/JGI, 2:1, w/w; CTS-JGI-2) exhibited the best emulsifying ability and stability against NaCl solution, in vitro antioxidant activity, and cholesterol-lowering ability. CTS-JGI-2 stabilized oil-in-water nano-emulsion improved resveratrol (RES) and quercetin (QUE) encapsulation efficiency (80.96% for RES and 93.13% for QUE) and stability during the simulated digestion process (73.23% for RES and 77.94% for QUE) due to the connection through hydrogen bonds, pi-anion, pi-sigma, and donors between CTS-JGI and RES/QUE. Taken together, the modification of JGI by conjugating with CTS through UTSA-MR could be an excellent method to improve the functional properties of JGI. CTS-JGI-2 is a potential conjugate with functions that can be used to encapsulate functional substances in the stabilized nano-emulsion.

Effect of ultrasound pretreatment on the functional and antioxidant properties of fermented and germinated Lupin protein isolates grafted with glucose

BACKGROUND

This study examined the functional and antioxidant properties of Maillard reaction (MR) products of lupin protein isolate (LPI), fermented (FLPI), and germinated (GLPI) with glucose (G), treated with ultrasound (US) at different power levels (20-40-60-80%) for 15 min. The MR was conducted in a water bath for 180 min at 90 °C.

RESULTS

The Trolox-equivalent antioxidant capacity (TEAC) values were found to be 46.79%, 56.43%, and 35.56% for the control (C), 58.99%, 80.17%, and 69.73% for conjugates of LPI-G, FLPI-G, and GLPI-G treated at 80% US, respectively. The maximum 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of LPI-G, FLPI-G, and GLPI-G was found to be 39.68%, 59.54%, and 48.41%, respectively after 80% US. The FLPI-G sample showed the highest antioxidant activity compared with the samples treated at the same power level for DPPH and TEAC. The Fe-chelating activity of GLPI-G showed significant differences when compared with FLPI-G. The solubility of LPI-G, FLPI-G, and GLPI-G increased with increasing US power. The highest solubility was 74.29% for 80% US-treated GLPI-G. The emulsifying activity index (EAI) increased at 20% US and decreased with further increase in the US power. The EAI and emulsifying stability index (ESI) were negatively affected by the MR and US processes.

CONCLUSION

The findings of current study proved that conjugation of LPI with G with the MR and with US pretreatment is an effective method for improving the bio- and techno-functional properties of LPI. It is therefore likely that the properties of plant proteins modified by biochemical and physical treatments may widen their applications in the food industry. © 2021 Society of Chemical Industry.

Growth performance and meat quality from broiler chickens reared with zeolite and halloysite in feed and straw pellet

The study's aim was to analyze the effects of different levels of halloysite (H) and zeolite (Z) in feed and pellets on the growth and meat quality in chickens; 500 Ross 308 broilers were assigned to five groups (1 g, control; 2-5 g, experimental). In Groups 2-5, different proportions of Z and H in feed (25:75 ratio; 0.5% to 2%) and pellet in kg/m² (2, 0.650H; 3, 0.325H and 0.325Z; 4, 0.650Z; 5, 0.160H and 0.490Z) were used. Body weight was higher than 1 in all experimental groups, and carcass weight was higher, except for Group 2. The feed consumption was lower in Groups 3 and 5 than in Group 4. The breast muscle weight was higher in Group 3 than in the control group. In Groups 2, 3, and 5, the water holding capacity in the breast muscles was better than in Group 4 and in the leg muscles in Groups 3 and 4 than in Groups 1 and 5. Most of the tested characteristics indicate a beneficial effect of aluminosilicates in feed and litter on the growth and quality of meat.

Effects of sugars on the flavor and antioxidant properties of the Maillard reaction products of camellia seed meals

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MRPs were obtained by heating camellia seed meal hydrolysates, and different sugars.

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The ratio of essential amino acids in R-MRPs was increased and the antioxidant activity was the highest.

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MR could improve the flavor and antioxidant activity of camellia seed meal.

In the present study, camellia seed meal Maillard reaction products (MRPs) were prepared using camellia seed meal protein as a raw material. The effects of MR on protein structure and volatile components of camellia seed meal were investigated by fluorescence, UV absorption, infrared spectroscopy, and gas chromatography-mass spectrometry. Not only the change of amino acid content in MRPs, but also the antioxidant capacity of MRPs and the antioxidant capacity after in vitro digestion were determined. Our result showed that the ratio of essential amino acids in R-MRPs was increased and the antioxidant activity was the highest. For the potential of MRPs as flavoring, our sensory evaluation results showed improved flavor and antioxidant activity of camellia seed meal after MR which can be used as flavoring agents at industrial level.

Structural, antioxidant, aroma, and sensory characteristics of Maillard reaction products from sweet potato protein hydrolysates as influenced by different ultrasound-assisted enzymatic treatments

Effects of energy-divergent ultrasound (EDU), energy-gathered ultrasound (EGU), and energy-gathered ultrasound-microwave (EGUM) on structure, antioxidant activities, aroma, and sensory attributes of Maillard reaction products (MRPs) from sweet potato protein hydrolysates (SPPH) were investigated. EGU and EGUM markedly enhanced the Maillard reaction (MR) progress. FTIR results revealed significant peptide structure changes in MRPs as compared to their SPPHs counterparts. EGU-MRPs exhibited the highest percentages in lower MW fractions of 200-3,000 Da, and presented a significantly enhanced ORAC value of 92.10 µg TE/mL (p < 0.05). Besides, EGU-MRPs and EGUM-MRPs showed higher content and quality of aroma compounds than other MRPs, and presented increased umami, sweetness, and sourness attributes, but decreased bitterness (p < 0.05). Their stronger umami taste was highly correlated to 1-naphthalenol, dodecanoic acid, <200, 200-500, 500-1,000 and 1,000-3,000 Da. Thus, EGU and EGUM assisted enzymatic hydrolysis coupled with MR might be promising ways to produce natural flavoring with improved antioxidant activities.

Impact of pH-dependent succinylation on the structural features and emulsifying properties of chicken liver protein

This work aims at investigating the pH-regulated relationship between the structural features and emulsifying properties of chicken liver protein (CLP) during succinylation and related mechanisms behind. The results demonstrated that the major succinylation sites occurred at lysine, histidine and tyrosine of CLP, and the succinylation degree increased by 30.66% as pH increased to 10. The succinylation pH elevation increased the solubility and oil absorption capacity of CLP, thus favoring its improvement in emulsifying properties, due to the succinylation process-induced increase in surface charge density and amphiphilic balance as well as modified network structure. However, the surface hydrophobicity of succinylated products decreased by 10.75% when the pH increased from 7 to 10. Besides, succinylation-induced variations in electrostatic repulsive and particle size distribution greatly improved the storability of the emulsions. These results suggested the great potential of pH-modulated succinylation to regulate the structure-property relationship of protein-based products.

Glucan Conversion and Membrane Recovery of Biomimetic Cellulosomes During Lignocellulosic Biomass Hydrolysis

Enzyme immobilization has been identified as one way to recycle enzymes and reduce processing costs during enzymatic hydrolysis of lignocellulosic materials. However, most immobilization methods have not been attractive to lignocellulosic processing plants. In this study, cellulase enzymes were attached to a copolymer of glycidyl methacrylate (GMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) to make polymer-enzyme conjugates (PECs) and facilitate recovery using a 50-kDa molecular weight cutoff membrane. Glucan conversion during biomass hydrolysis was investigated using new PECs and PECs recovered after an initial hydrolysis stage. Enzyme immobilization on PECs did not reduce effectiveness during the initial hydrolysis. Temperature and pH showed similar effects on free enzymes and PECs. PECs facilitated higher conversion rates than free enzymes at high biomass loadings. Recovered PECs were used to achieve approximately 100% glucan conversion in a subsequent hydrolysis step when supplemented with 40% of the free enzyme used in the first stage. The combination of PECs and membrane recovery has the potential to reduce hydrolysis cost during cellulosic bioprocessing.

Structural and antimicrobial properties of Maillard reaction products in chicken liver protein hydrolysate after sonication

This study aimed to investigate the structural and antimicrobial properties of Maillard reaction products (MRPs) in chicken liver protein (CLP) and its hydrolysate (CLPH) after sonication (SCLPH). The MRPs of CLP (CLPM), CLPH (CLPHM) and SCLPH (SCLPHM) were analyzed by several spectrometric techniques. The molecular weights of the CLPHM and SCLPHM were primarily between 1.35 kDa and 17 kDa. Moreover, the molecular weights in the CLPHM and SCLPHM below 1.35 kDa were increased, which indicated that cross-linking and thermal degradation occurred during the Maillard reaction (MR). The SCLPHM showed an obvious network skeleton, and the surface had many small crystal-shaped particles after ultrasound treatment and MR by scanning electron microscopy. The SCLPHM had more negative charges than the CLPHM, thus effectively inhibiting the growth of S. saprophyticus and E. coli. MR and ultrasound treatment could be a promising technology to expand the application prospects of low-value meat byproducts.