Cross-linking reactions in food proteins and proteomic approaches for their detection

Optimizing aquasoya protein: Insights of various pre-treatments for enhancing the upcycling potential from small black bean by-product

To minimize resource waste and promote recycling, it is essential to recover nutritional components from by-products. This study aimed to optimize of Aquasoya protein (AS-P) recovery from small black bean by-products, focusing on the effects of pH adjustments, sonication, and fractionation on protein yield, solubility, and structural integrity. Alkaline treatment at pH 8.5 significantly enhanced AS-P recovery yield (77.60 %) and protein concentration (421.16 μg/mL), attributed to the increased solubility and effective removal of non-protein components. Sonication for 10 min exhibited the highest protein solubility (88.69 %) post-fractionation, indicating reduced protein aggregation. Fractionation was crucial in minimizing browning reactions and enhancing protein purity by eliminating oligosaccharides and impurities. SDS-PAGE analysis revealed distinct protein bands from alkaline treatment, while sonication resulted in lipoxygenase (LOX) protein degradation. Principal Component Analysis (PCA) emphasized that fractionation notably enhances the stability and quality of AS-P, making it as a viable ingredient for food applications.

Empowering canonical biochemicals with cross-linked novelty: Recursions in applications of protein cross-links

Diversity in the biochemical workhorses of the cell-that is, proteins-is achieved by the innumerable permutations offered primarily by the 20 canonical L-amino acids prevalent in all biological systems. Yet, proteins are known to additionally undergo unusual modifications for specialized functions. Of the various post-translational modifications known to occur in proteins, the recently identified non-disulfide cross-links are unique, residue-specific covalent modifications that confer additional structural stability and unique functional characteristics to these biomolecules. We review an exclusive class of amino acid cross-links encompassing aromatic and sulfur-containing side chains, which not only confer superior biochemical characteristics to the protein but also possess additional spectroscopic features that can be exploited as novel chromophores. Studies of their in vivo reaction mechanism have facilitated their specialized in vitro applications in hydrogels and protein anchoring in monolayer chips. Furthering the discovery of unique canonical cross-links through new chemical, structural, and bioinformatics tools will catalyze the development of protein-specific hyperstable nanostructures, superfoods, and biotherapeutics.

Optimization of liquid chromatography and mass spectrometry parameters based on LC-QQQ: A case study on lysinoalanine

Lysinoalanine (LAL), commonly formed in high-protein foods, raises concerns due to its nephrotoxicity and potential reduction in nutritional properties, making its accurate detection crucial for food safety. Liquid chromatography-tandem quadrupole mass spectrometry (LC-QQQ) plays a pivotal role in the quantification of compounds, and its accuracy and sensitivity are significantly influenced by specific liquid chromatography (LC) and mass spectrometry (MS) parameters. However, the procedure and considerations for LC and MS parameters optimization have often not been discussed in depth in existing literature. Therefore, this study used LAL as a model compound to systematically optimize the key LC and MS parameters using LC-QQQ. The optimized MS parameters were as follows: parent ion m/z-234.2, capillary voltage-3.5 kV, cone voltage-30 V, desolvation temperature-500 °C, daughter ion m/z-84.2, and collision voltage-20 V. The optimized LC parameters were as follows: buffer-0.1 % formic acid (v/v), column, Polaris 3 Amide-C18 (150 × 3 mm, 3 μm). Under these optimized conditions, the limit of detection (LOD) for LAL was detected as 13 ng/mL in multiple reaction monitoring mode, which is considerably lower than the 125 ng/mL detected by LC-QQQ and marginally lower than the 15.23 ng/mL detected by LC-quadrupole Exactive Orbitrap MS reported in previous studies. Additionally, this study elucidates the critical factors to be considered when selecting LC and MS parameters, providing valuable insights into the detection of other compounds using LC-QQQ.

Determination of process parameters and precipitation methods for potential large-scale production of sugar beet leaf protein concentrate

BACKGROUND

Sugar beet is one of the most produced industrial plants in the world, and during manufacturing it produces a large quantity of leaf waste. Because this waste is rich in protein, this study aimed to identify an efficient method for producing large-scale protein concentrate from sugar beet leaves.

RESULTS

Results showed that protein extraction from fresh leaves was more effective than from dried leaves. Maximum protein extraction was achieved at pH 9, compared with pH 7 or 8. Blanching as a pretreatment reduced protein yield during isoelectric precipitation, with a yield of 2.31% compared to 20.20% without blanching. Consequently, blanching was excluded from the extraction process. After extraction, isoelectric precipitation, heat coagulation, and isoelectric-ammonium sulfate precipitation were compared. Although the latter resulted in the highest protein yield, Fourier transform infrared analysis revealed that excessive salt was not removed during dialysis, making it unsuitable for scale-up due to its additional cost and complexity. Therefore, isoelectric precipitation was selected as the appropriate method for protein precipitation from sugar beet leaves. To increase yield, extractions were assisted by ultrasound or enzyme addition. Ultrasound-assisted extraction resulted in an increased protein yield from 20.20% to 28.60%, while Pectinex Ultra SP-L-assisted extraction was the most effective, increasing protein yield from 20.20% to 38.09%.

CONCLUSION

Proteins were extracted from fresh sugar beet leaves using optimum conditions (50 °C, 30 min, pH 9) and precipitated at isoelectric point, with enzymatic-assisted extraction yielding the maximum protein recovery. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Formation of di-Tyrosine in pasteurized milk during shelf storage

Formation of the protein crosslink di-Tyrosine was studied in PET-bottled pasteurized milk exposed to fluorescent light in a commercial display cabinet. An HPLC method with fluorescence detection was developed and intra-laboratory validated using pure di-Tyrosine synthesized on purpose. Di-Tyrosine was detected after 1-day lightening and increased up to 7 days, reaching around 250 and 320 µg/g protein in whole and partly skimmed milk, respectively. Afterward, a progressive decrease occurred. By transmission electron microscopy with specific immune gold labelling, presence of di-Tyrosine was observed for the first time on the surface of casein micelles of lightened milk. The crosslink formation, however, did not bring to protein aggregation phenomena detectable by laser light scattering measurements. Exposure to light also induced degradation of riboflavin and decrease of yellowness index. Di-Tyrosine proved to be a suitable indicator to evaluate the progress of protein oxidation in pasteurized milk during storage on the market.

Proteomic Characterization of Wheat Protein Fractions Taken at Different Baking Conditions

Food processing conditions affect the structure, solubility, and therefore accurate detection of gluten proteins. We investigated the influence of dough, bread, and pretzel making on the composition of different wheat protein fractions obtained by Osborne fractionation. The albumin/globulin, gliadin, and glutenin fractions from flour, dough, crispbread, bread, and pretzel were analyzed using RP-HPLC, SDS-PAGE, and untargeted nanoLC-MS/MS. This approach enabled an in-depth profiling of the fractionated proteomes and related compositional changes to processing conditions (mixing, heat, and alkali treatment). Overall, heat treatment demonstrated the most pronounced effect. Label-free quantitation revealed significant changes in the relative abundances of 82 proteins within the fractions of bread crumb and crust in comparison to flour. Certain gluten proteins showed shifts or reductions in particular fractions, indicating their incorporation into the gluten network through SS and non-SS cross-links. Other gluten proteins were enriched, suggesting their limited involvement in the gluten network formation.

IgE Recognition and Structural Analysis of Disulfide Bond Rearrangement and Chemical Modifications in Allergen Aggregations in Roasted Peanuts

Given that roasting changes the structure and allergenicity of peanut allergens, the structural information of peanut allergens must be expounded to explain the alteration in their allergenicity. This work focused on allergen aggregations (AAs) in roasted peanuts. IgE recognition capability was assessed via western blot analysis. The disulfide bond (DB) rearrangement and chemical modification in AAs were identified by combining mass spectroscopy and software tools, and structural changes induced by cross-links were displayed by molecular dynamics and PyMOL software. Results showed that AAs were strongly recognized by IgE and cross-linked mainly by DBs. The types of DB rearrangement in AAs included interprotein (98 peptide pairs), intraprotein (22 peptide pairs), and loop-linked (6 peptides) DBs. Among allergens, Ara h 2 and Ara h 6 presented the most cysteine residues to cross-linkf with others or themselves. DB rearrangement involved IgE epitopes and induced structural changes. Ara h 1 and Ara h 3 were predominantly chemically modified. Moreover, chemical modification altered the local structures of proteins, which may change the allergenic potential of allergens.

Proteomics as a promising biomarker in food authentication, quality and safety: A review

Adulteration and mislabeling have become a very common global malpractice in food industry. Especially foods of animal origin are prepared from plant sources and intentionally mislabeled. This type of mislabeling is an important concern in food safety as the replaced ingredients may cause a food allergy or toxicity to vulnerable consumers. Moreover, foodborne pathogens also pose a major threat to food safety. There is a dire need to develop strong analytical tools to deal with related issues. In this context, proteomics stands out as a promising tool used to report the aforementioned issues. The development in the field of omics has inimitable advantages in enabling the understanding of various biological fields especially in the discipline of food science. In this review, current applications and the role of proteomics in food authenticity, safety, and quality and food traceability are highlighted comprehensively. Additionally, the other components of proteomics have also been comprehensively described. Furthermore, this review will be helpful in the provision of new intuition into the use of proteomics in food analysis. Moreover, the pathogens in food can also be identified based on differences in their protein profiling. Conclusively, proteomics, an indicator of food properties, its origin, the processes applied to food, and its composition are also the limelight of this article.

Focus on the Protein Fraction of Sports Nutrition Supplements

Increasing awareness of balanced diet benefits is boosting the demand for high-protein food and beverages. Sports supplements are often preferred over traditional protein sources to meet the appropriate dietary intake since they are widely available on the market as stable ready-to-eat products. However, the protein components may vary depending on both sources and processing conditions. The protein fraction of five commercial sports supplements was characterized and compared with that of typical industrial ingredients, i.e., whey protein concentrates and isolates and whey powder. The capillary electrophoresis profiles and the amino acid patterns indicated that, in some cases, the protein was extensively glycosylated and the supplemented amino acids did not correspond to those declared on the label by manufacturers. The evaluation by confocal laser scanning microscopy evidenced the presence of large aggregates mainly enforced by covalent crosslinks. The obtained findings suggest that, beside composition figures, provisions regarding sports supplements should also consider quality aspects, and mandatory batch testing of these products would provide more reliable information to sport dieticians.

Effective Use of Plant Proteins for the Development of "New" Foods

Diversity in our diet mirrors modern society. Affluent lifestyles and extended longevity have caused the prevalence of diabetes and sarcopenia, which has led to the increased demand of low-carb, high-protein foods. Expansion of the global population and Westernization of Asian diets have surged the number of meat eaters, which has eventually disrupted the supply–demand balance of meat. In contrast, some people do not eat meat for religious reasons or due to veganism. With these multiple circumstances, our society has begun to resort to obtaining protein from plant sources rather than animal origins. This “protein shift” urges food researchers to develop high-quality foods based on plant proteins. Meanwhile, patients with food allergies, especially gluten-related ones, are reported to be increasing. Additionally, growing popularity of the gluten-free diet demands development of foods without using ingredients of wheat origin. Besides, consumers prefer “clean-label” products in which products are expected to contain fewer artificial compounds. These diversified demands on foods have spurred the development of “new” foods in view of food-processing technologies as well as selection of the primary ingredients. In this short review, examples of foodstuffs that have achieved tremendous recent progress are introduced: effective use of plant protein realized low-carb, high protein, gluten-free bread/pasta. Basic manufacturing principles of plant-based vegan cheese have also been established. We will also discuss on the strategy of effective development of new foods in view of the better communication with consumers as well as efficient use of plant proteins.