Functional Proteins from Biovalorization of Peanut Meal: Advances in Process Technology and Applications

Physicochemical, techno-functional, biochemical and structural characterization of a protein isolate from groundnut (Arachis hypogaea L.) paste treated with high-intensity ultrasound

The objective of this research was to evaluate the effect of ultrasound (HISound) (200, 400 and 600 W; 15-30 min) on the physicochemical, biochemical and structural techno-functional properties of a groundnut paste protein isolate (GPPI). HISound increased the contents of free sulfhydryls (552.22 %), total sulfhydryls (124.68 %) and α-helix (389.75 %), as well as molecular flexibility (50.91 %), hydrophobic surface (38.99 %), and particle size (171.45 %) of GPPI, which improved protein solubility by 8.05 %, oil holding capacity by 73.54 %, emulsifying stability index by 226.25 % and foaming capacity by 216.00 %, compared with non-sonicated GPPI. Also, the microstructure analysis revealed smooth structures, with molecular weights in the range of 13.88-67.07 kDa. Pearson analysis determined some highly significant correlations (r ≥ 0.90, p < 0.01) between some GPPI protein properties. The improvement of GPPI properties by HISound could contribute to its use as an ingredient for human consumption.

Isolation, identification, and chelation mechanism of ferrous-chelating peptide from peanut protein hydrolysate

BACKGROUND

Peanut peptides can chelate iron but their chelation mechanism remains unclear. The purpose of this study is to separate peanut ferrous-chelating peptides and explore the chelation mechanism of peanut peptides with iron.

RESULTS

Peanut peptide component F-122, which had a higher chelation rate, was separated using ultrafiltration, gel filtration chromatography, and ion exchange chromatography, achieving a ferrous chelation rate of 90.7%. Six peptide segments were screened and their amino acid sequences were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Spectral analysis confirmed that the chelation between peanut peptides and ferrous ions occurred and a new substance was formed. Molecular docking simulation indicated that the amino acids in peanut peptides involved in the chelating reaction were glutamic acid, arginine, glycine, threonine, phenylalanine, and lysine. The binding sites included the main chain oxygen atom, side chain oxygen atom, and carboxyl oxygen atom of amino acid.

CONCLUSION

The isolated peanut peptide had a higher ferrous-chelation rate. The chelating mechanism of peanut peptide with ferrous ion was elucidated. This study provides a theoretical basis for the development of new peptide-ferrous preparations. © 2024 Society of Chemical Industry.

Identification of calcium chelating peptides from peanut protein hydrolysate and absorption activity of peptide-calcium complex

BACKGROUND

Peanut peptides have good chelating ability with metal ions. However, there are few studies on the chelation mechanism of peanut peptides with calcium and absorption properties of peptide-calcium complex.

RESULTS

Peptides with high calcium chelating rate were isolated and purified from peanut protein hydrolysate (PPH), and the chelation rate of component F21 was higher (81.4 ± 0.8%). Six peptides were identified from component F21 by liquid chromatography-tandem mass spectrometry, and the frequency of acidic amino acids and arginine in the amino acid sequence was higher in all six peptides. Peanut peptide-calcium complex (PPH21-Ca) was prepared by selecting component F21 (PPH21). Ultraviolet analysis indicated that the chelate reaction occurred between peanut peptide and calcium ions. Fourier transform infrared analysis showed that the chelating sites were carboxyl and amino groups on the amino acid residues of peptides. Scanning electron microscopy revealed that the surface of peanut peptide had a smooth block structure, but the surface of the complex had a granular morphology. Caco-2 cell model tests revealed that the bioavailability of PPH21-Ca was 58.4 ± 0.5%, which was significantly higher than that of inorganic calcium at 37.0 ± 0.4%.

CONCLUSION

Peanut peptides can chelate calcium ions by carboxyl and amino groups, and the peptide-calcium complex had higher bioavailability. This study provides a theoretical basis for the development of new calcium supplement products that are absorbed easily. © 2024 Society of Chemical Industry.

Assessment of Peanut Protein Powder Quality by Near-Infrared Spectroscopy and Generalized Regression Neural Network-Based Approach

The global demand for protein is on an upward trajectory, and peanut protein powder has emerged as a significant player, owing to its affordability and high quality, with great future market potential. However, the industry currently lacks efficient methods for rapid quality testing. This research paper addressed this gap by introducing a portable device with employed near-infrared spectroscopy (NIR) to quickly assess the quality of peanut protein powder. The principal component analysis (PCA), partial least squares (PLS), and generalized regression neural network (GRNN) methods were used to construct the model to further enhance the accuracy and efficiency of the device. The results demonstrated that the newly established NIR method with PLS and GRNN analysis simultaneously predicted the fat, protein, and moisture of peanut protein powder. The GRNN model showed better predictive performance than the PLS model, the correlation coefficient in calibration (Rcal) of the fat, the protein, and the moisture of peanut protein powder were 0.995, 0.990, and 0.990, respectively, and the residual prediction deviation (RPD) were 10.82, 10.03, and 8.41, respectively. The findings unveiled that the portable NIR spectroscopic equipment combined with the GRNN method achieved rapid quantitative analysis of peanut protein powder. This advancement holds a significant application of this device for the industry, potentially revolutionizing quality testing procedures and ensuring the consistent delivery of high-quality products to fulfil consumer desires.

Studies on the Increasing Saltiness and Antioxidant Effects of Peanut Protein Maillard Reaction Products

The salt taste-enhancing and antioxidant effect of the Maillard reaction on peanut protein hydrolysates (PPH) was explored. The multi-spectroscopic and sensory analysis results showed that the Maillard reaction products (MRPs) of hexose (glucose and galactose) had slower reaction rates than those of pentose (xylose and arabinose), but stronger umami and increasing saltiness effects. The Maillard reaction can improve the flavor of PPH, and the galactose-Maillard reaction product (Ga-MRP) has the best umami and salinity-enhancing effects. The measured molecular weight of Ga-MRP were all below 3000 Da, among which the molecular weights between 500-3000 Da accounted for 46.7%. The products produced during the Maillard reaction process resulted in a decrease in brightness and an increase in red value of Ga-MRP. The amino acid analysis results revealed that compared with PPH, the content of salty and umami amino acids in Ga-MRPs decreased, but their proportion in total free amino acids increased, and the content of bitter amino acids decreased. In addition, the Maillard reaction enhances the reducing ability, DPPH radical scavenging ability, and Fe2+ chelating ability of PPH. Therefore, the Maillard reaction product of peanut protein can be expected to be used as a substitute for salt seasoning, with excellent antioxidant properties.

Unlocking the Nutraceutical Potential of Legumes and Their By-Products: Paving the Way for the Circular Economy in the Agri-Food Industry

Legumes, including beans, peas, chickpeas, and lentils, are cultivated worldwide and serve as important components of a balanced and nutritious diet. Each legume variety contains unique levels of protein, starch, fiber, lipids, minerals, and vitamins, with potential applications in various industries. By-products such as hulls, rich in bioactive compounds, offer promise for value-added utilization and health-focused product development. Various extraction methods are employed to enhance protein extraction rates from legume by-products, finding applications in various foods such as meat analogs, breads, and desserts. Moreover, essential fatty acids, carotenoids, tocols, and polyphenols are abundant in several residual fractions from legumes. These bioactive classes are linked to reduced incidence of cardiovascular diseases, chronic inflammation, some cancers, obesity, and type 2 diabetes, among other relevant health conditions. The present contribution provides a comprehensive review of the nutritional and bioactive composition of major legumes and their by-products. Additionally, the bioaccessibility and bioavailability aspects of legume consumption, as well as in vitro and in vivo evidence of their health effects are addressed.

Research Advances in the High-Value Utilization of Peanut Meal Resources and Its Hydrolysates: A Review

Peanut meal (PM) is a by-product of extracting oil from peanut kernels. Although peanut meal contains protein, carbohydrates, minerals, vitamins, and small amounts of polyphenols and fiber, it has long been used as a feed in the poultry and livestock industries due to its coarse texture and unpleasant taste. It is less commonly utilized in the food processing industry. In recent years, there has been an increasing amount of research conducted on the deep processing of by-products from oil crops, resulting in the high-value processing and utilization of by-products from various oil crops. These include peanut meal, which undergoes treatments such as enzymatic hydrolysis in industries like food, chemical, and aquaculture. The proteins, lipids, polyphenols, fibers, and other components present in these by-products and hydrolysates can be incorporated into products for further utilization. This review focuses on the research progress in various fields, such as the food processing, breeding, and industrial fields, regarding the high-value utilization of peanut meal and its hydrolysates. The aim is to provide valuable insights and strategies for maximizing the utilization of peanut meal resources.

Microbial proteases and their applications

Proteases (proteinases or peptidases) are a class of hydrolases that cleave peptide chains in proteins. Endopeptidases are a type of protease that hydrolyze the internal peptide bonds of proteins, forming shorter peptides; exopeptidases hydrolyze the terminal peptide bonds from the C-terminal or N-terminal, forming free amino acids. Microbial proteases are a popular instrument in many industrial applications. In this review, the classification, detection, identification, and sources of microbial proteases are systematically introduced, as well as their applications in food, detergents, waste treatment, and biotechnology processes in the industry fields. In addition, recent studies on techniques used to express heterologous microbial proteases are summarized to describe the process of studying proteases. Finally, future developmental trends for microbial proteases are discussed.