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Selecting suitable soybean cultivars is important for food processing and exploring their endowment with desirable physiological functions. We applied the fractionation method previously established to compare soy protein composition among cultivars to promote such a selection. More than 95% of the proteins in soybean cotyledons were extracted from 13 soybean cultivars using a high‐concentration salt solution. The extracted proteins were fractionated into five fractions, namely oil body‐associated protein (OBAP), polar lipid‐associated protein (PLAP), globulins (11S and 7S), and whey by centrifugation after tuning the solubility behavior of the proteins with various solutions. Protein species in each fraction were analyzed by SDS‐PAGE. Protein content in the total extract and five fractions was quantified to characterize the protein composition of soybean cultivars. The correlation between the protein content of each fraction and the total protein in cotyledon was investigated. A strong positive correlation was found only for the 11S fraction (r = 0.82), followed by a positive correlation in the 7S fraction (r = 0.65). Thus, we surmised that the increased protein content in soybean was due to increased globulin content. Furthermore, the calculation of the average ratio of protein content in each fraction indicated the globulin fraction (7S and 11S) to be 52%, the lipophilic protein fraction (OBAP and PLAP) to be 33%, and the whey fraction to be 13%. The preparation method employed in this study is a promising tool for efficiently comparing the protein composition of soybean cultivars to evaluate the potential use of cultivars for food production. [ABSTRACT FROM AUTHOR]

The lateral eyes of the horseshoe crab, Limulus polyphemus, are the largest compound eyes within recent Arthropoda. The cornea of these eyes contains hundreds of inward projecting elongated cuticular cones and concentrate light onto proximal photoreceptor cells. Although this visual system has been extensively studied before, the precise mechanism allowing vision has remained controversial. Correlating high‐resolution quantitative refractive index (RI) mapping and structural analysis, it is demonstrated how gradients of RI in the cornea stem from structural and compositional gradients in the cornea. In particular, these RI variations result from the chitin‐protein fibers architecture, heterogeneity in protein composition, and bromine doping, as well as spatial variation in water content resulting from matrix cross‐linking on the one hand and cuticle porosity on the other hand. Combining the realistic cornea structure and measured RI gradients with full‐wave optical modeling and ray tracing, it is revealed that the light collection mechanism switches from refraction‐based graded index (GRIN) optics at normal light incidence to combined GRIN and total internal reflection mechanism at high incident angles. The optical properties of the cornea are governed by different mechanisms at different hierarchical levels, demonstrating the remarkable versatility of arthropod cuticle. [ABSTRACT FROM AUTHOR]

Background and Objectives: The mechanisms underlying the effects of proteins on the eating quality of rice remain elusive. In this study, the effect of content and secondary structure of four rice proteins (glutelin, globulin, albumin, and prolamin) on eating quality was investigated with rice subjected to nitrogen treatment at 160, 210, 260, 315, and 420 kg N/ha in the field. Findings: The results showed that applying nitrogen fertilizer remarkably increased glutelin and globulin contents (p <.05), especially the methionine content of globulin, leading to increased hardness of cooked rice. Moreover, excessive nitrogen significantly reduced the ratio of the prolamin α‐helix structure (p <.05), which had a significant correlation with hardness and pasting temperature (p <.05), at correlation coefficients of −0.859 and 0.828, respectively. Conclusion: Besides protein content, the changes in amino acid content and protein secondary structure were also closely related to the eating quality of rice. Significance and Novelty: Those results provided a new idea for breeding, cultivating, and processing technology regulation aimed at improving the eating quality of rice. [ABSTRACT FROM AUTHOR]

BACKGROUND: The resistance of proteins to gastrointestinal digestion contributes to their ability to act as allergens. Nearcomplete digestion of protein in wheat products is important with respect to avoiding the potential immunogenic effects of undigested peptides. Five modern US wheat classes (soft red winter, hard winter, hard red spring, club and durum) including 17 wheat varieties, as well as three ancient wheat classes (spelt, emmer and einkorn) including nine wheat varieties, were analyzed for kernel hardness (KH) and flour protein characteristics, in addition to in vitro protein digestibility (IVPD) of cooked flour, flour without albumins and globulins (FWOAG), gluten, albumins, and globulins, aiming to identify the factors influencing the protein digestibility of flour. RESULTS: IVPDs of flour, FWOAG, gluten and albumins of wheat varieties ranged from 86.5% to 92.3%, 85.8% to 90.3%, 90.6% to 94.6% and 74.8% to 85.1%, respectively. The IVPD of gluten was significantly higher than the IVPDs of flour and FWOAG, indicating that non-protein components substantially affect protein digestibility. Significant differences were observed in IVPDs of flour and albumins among eight wheat classes, but not in the IVPDs of FWOAG, gluten and globulins. There were apparent differences in undigested protein bands and intensities of wheat classes with low and high flour IVPDs. KH and albumin proportion exhibited negative and positive relationships, respectively, with flour IVPD. CONCLUSION: The results of the present study demonstrate that KH, non-protein components and albumin proportion have a major influence on protein digestion and need to be considered when developing wheat cultivars with higher protein digestibility. [ABSTRACT FROM AUTHOR]

Background: In recent years there has been a visible trend among consumers to move away from consuming meat in favor of plant products. Meat producers have therefore been trying to meet the expectations of consumers by introducing new products to the food market with a greater proportion of plant ingredients. Meat products are enriched not only by the addition of vegetable oils but also by ground or whole oilseeds or their preparation. In this study, we present in‐solution tryptic digestion and an ultra‐performance liquid chromatography coupled to quadrupole time‐of‐flight mass spectrometry (UHPLC‐Q‐TOF‐MS/MS)‐based proteomics approach to investigate specific proteins and peptides of ten oilseed cakes, by‐products of cold pressing oil from coconut, evening primrose, hemp, flax, milk thistle, nigella, pumpkin, rapeseed, sesame, and sunflower seeds, for authentication purposes. Results: We identified a total of 229 unique oilseed proteins. The number of specific proteins varied depending on the sample, from 4 to 48 in evening primrose and sesame. Moreover, we identified approximately 440 oilseed unique peptides in the cakes of all the analyzed oilseeds; the largest amounts were found in sesame (107 peptides), sunflower (100), pumpkin, hemp (42), rapeseed (36), and flax cake (35 peptides). Conclusions: We provide novel information on unique / species‐specific peptide markers that will extend the scope of testing the authenticity of a wide range of foods. The results of this peptide discovery experiment may further contribute to the development of targeted methods for the detection and quantification of oilseed proteins in processed foods, and thus to the improvement of food quality. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background and objectives: Despite the strong influence of proteins on quality, no research has been performed to determine the association between protein composition and quality improvements of durum wheat produced in North Dakota (ND). This research objected to identify improvements of quality traits and determine its association with variations in protein composition using 32 durum genotypes released between 1956 and 2013 in ND. Findings: Certain durum quality parameters, such as kernel weight, mixing properties, and pasta‐making characteristics, improved over the last 50 years of durum breeding. Total protein content showed nonsignificant variation; however, protein composition parameters varied significantly. Specifically, SDS extractable LMW polymeric proteins and gliadins decreased while unextractable polymeric proteins increased. These changes in protein composition parameters were significantly correlated with dough and pasta cooking quality traits. Conclusions: Enhancement of protein composition is primarily responsible for the improvement of mixing quality and cooked pasta firmness seen in durum cultivars released over the last 50 years. Significance and novelty: These findings demonstrate that genetic advancement of mixing and pasta quality traits can be attained by segregation of genotypes based on protein composition in durum wheat breeding. [ABSTRACT FROM AUTHOR]

Pressed cake from rapeseed ( Brassica napus L.) is a promising plant protein source not yet utilised for human consumption due to the presence of antinutrients such as glucosinolates. Protein solubility is a crucial parameter influencing the functionality and thereby the applicability of proteins as food ingredients. A novel cruciferin-rich rapeseed protein product was produced by an aqueous processing method in pilot plant scale. Intact glucosinolates were conserved by this procedure and largely removed from the protein products. Protein solubility in this product was examined when dispersed in 50 m m phosphate buffer, pH 8.0 with varying NaCl concentration (0-500 m m). Unexpectedly, a salting-out effect was observed of the globulin proteins, as 15.9 ± 0.6% protein was in solution at 500 m m added NaCl, whereas 21.5 ± 1.1% was solubilised without added NaCl; whether the observed effects originates from lipid and fibre constituents in the product remains to be resolved. [ABSTRACT FROM AUTHOR]

BACKGROUND Texture and water holding are important for silken tofu manufacturers and are affected by many factors, including soybean variety and processing conditions. In this study we evaluated these two key quality attributes of silken tofu produced from two soybean varieties - Bunya and Cowrie - using a soak or a dry processing method with glucono-δ-lactone or nigari as coagulant at concentrations of 1.5-5.0 g kg−1. RESULTS The soak method produced substantially firmer silken tofu with either coagulant. The optimum coagulant concentration to achieve maximum hardness was 2.5-3.0 g kg−1. At 3.0 g kg−1, Bunya produced silken tofu with firmer texture for each of the coagulant-method combinations and lower water loss, an indicator for water holding capacity, for the soak method. The two varieties differed significantly in the composition of major protein subunits for the seed and soymilk. Bunya had no 11SA4, less 11S and more 7S and therefore a lower 11S/ 7S ratio. CONCLUSION Both variety and processing conditions affect textural properties and water loss of silken tofu. The absence of 11SA4 and subsequent protein subunit compositions are important in determining these two key quality attributes. Variety Bunya produces silken tofu with firmer texture and lower water loss. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Crevicular fluid (CF) analysis is a potential tool for site-specific diagnosis of periodontal disease activity. In this study, CF was collected using a novel washing method from 91 sites in 18 adult periodontitis patients both before and after conventional periodontal treatment. The sites studied were classified according to their clinical status and the number of polymorpho-nuclear leukocytes (PMN's) in CF samples. CF proteins were analyzed from individual sites with gel electrophoresis (SDS-PAGE). Furthermore, both the cell-bound and soluble neutral proteolytic activities of the samples were determined. Albumin was the main protein both in healthy and slightly inflamed sites. The most severely inflamed sites were characterized by high levels of low molecular weight (LMW) proteins (mol. weight ca. 12000) and strong cell-bound neutral proteolytic activity. Scaling and root planing reduced both the LMW proteins and neutral proteolytic activity markedly in pockets responding well to treatment. The levels of the LMW proteins in CF correlated with the cell-bound neutral proteolytic activity, which reflected the number of PMN's in the sample. The present results suggest that the appearance of the LMW proteins in CF is associated with the periodontal inflammatory status of the site. [ABSTRACT FROM AUTHOR]

The isolated protein bodies of Cytisus scoparius (L.) Link and Cytisus scoparius ssp. maritimus (Rouy) Heywood were observed by scanning electron microscopy; they showed comparable shapes and sizes. The protein content and the sub-unit composition of the fractionated albumins, vicilins and legumins, however, showed significant electrophoretic differences between the two plants, both at the qualitative and quantitative levels. [ABSTRACT FROM AUTHOR]

Protoplasts isolated from pear fruit at the end of the cell-division stage, 30 days after flowering (DAF), had already formed a large central vacuole and the vacuole occupied most of the protoplast. The changes in protein composition and density of the tonoplast (vacuolar membrane) were investigated during fruit development. After a linear sucrose density gradient centrifugation, the distribution of tonoplasts at 30 and 48 DAF was broad and began to narrow with further fruit development. This suggests that the tonoplast of young fruit is heterogeneous and becomes homogeneous with fruit development. The apparent density of the tonoplast at 30 DAF was approximately 1.12 g ml-1; it decreased with fruit development and was finally 1.09 g ml-1 in mature fruit. The phospholipid amount on the basis of tonoplast protein was 0.80 mg mg-1 at 30 DAF. It increased with fruit development, and finally reached 7.49 mg mg-1. This result indicates that the decrease in the density of the tonoplast was caused by the increase in the ratio of phospholipid to membrane protein. The protein composition of the tonoplast at each stage was quite different. The level of polypeptides of 94, 70, 61, 52, 48 and 41 kDa was low in young fruit and high in the middle or later stages of fruit development. In contrast, the level of a 76-kDa polypeptide was high in young fruit and decreased with fruit development. Although their functions are still unclear, these tonoplast proteins may play important roles in fruit development. [ABSTRACT FROM AUTHOR]

The halophyte Mesembryanthemum crystallinum (ice plant) has been suggested as a model for salt-tolerance in higher plants. To investigate salt-induced changes in polypeptide patterns at the cellular level, a light-grown callus of M. crystallinum with substantial chlorophyll content, was established and the effect of NaCI on the composition of phenol-extracted protein was examined by SDS- and 2D-polyacrylamide gel electrophoresis (PAGE). SDS-PAGE showed the accumulation of five polypeptides with estimated molecular masses of 40, 34, 32, 29 and 14 kDa was enhanced by the addition of 200 mM NaCl to the culture media. The addition of ABA (10 μM) or mannitol (400 mM) did not elicit the same degree of accumulation of these salt-specific proteins. These polypeptides were classified into two groups according to their course of induction: early-responsive (40, 34, 29 kDa) and late-responsive (32, 14 kDa) proteins. In addition, two polypeptides (20, 18 kDa) were transiently accumulated during salt treatment. Further separation of soluble proteins by 2-D gel electrophoresis, either isoelectric focusing (IEF) or non-equilibrium pH-gradient electrophoresis (NEPHGE) followed by SDS-PAGE, showed more alterations in accumulation of polypeptides by NaCl than 1-D gel electrophoresis. Overall, levels of more than 30% of basic polypeptides, detected by NEPHGE/SDS-PAGE, were altered by 200 mM NaCl treatment, while only 10% of neutral and acidic polypeptides, detected by IEF/SDS-PAGE, were changed. The enhanced expression of these proteins by salt in cultured cells is most likely related to the cellular responses to salinity, and not to the mechanism of CAM induction in this facultative halophyte. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates high ionic strength soluble (HIS) proteins, low ionic strength soluble (LIS) proteins and insoluble (IN) proteins from lean finely textured tissue (LFTT) derived from beef and pork trimmings. The study found out that LFTT had greater IN and LIS protein fractions and a smaller HIS protein fraction. HIS protein was confirmed as the important functional component in LFTT for gelation.

Many hair characteristics (e.g. color and curl) are genetically determined. Here, we investigated whether hair quality is also genetically controlled and related to differences in hair composition. Female, Caucasian subjects (n = 292) were recruited into this study and segmented by self-perceived hair quality and by permanent colorant usage. Hair fibers were collected and characterized by amino acid analysis, dry tensile elastic modulus testing and two-dimensional electrophoresis of hair protein extracts.Protein analysis revealed a string of 66 kDa proteins that correlated with hair of high quality. Loss of low molecular weight (14–29 kDa) proteins increased with colorant usage, particularly in hair of low quality. Amino acid analysis showed that the levels of serine and threonine across all the subjects followed bimodal frequency distributions suggestive of a genetic influence. Overall, data suggested that perception of quality was linked to high serine and threonine levels. In addition, where hair was colored, quality was associated with lower cysteic acid levels. Lower cysteic acid levels were not linked to lower colorant usage and our data suggest that high quality hair may be more resistant to colorant damage. Elastic modulus was significantly higher in hair of higher quality (4.65 GPa) compared to all medium and low quality hair combined (4.3 GPa),P < 0.02. This suggests a link between altered hair composition and mechanical properties. In conclusion, the composition and mechanical properties of hair have been linked to hair quality. We hypothesize that hair quality is thus likely to be genetically determined. Understanding of the links between hair composition and its properties could be utilized in the future for designing products targeted to each individual's hair make-up, and for producing diagnostic tools for determining hair quality. [ABSTRACT FROM AUTHOR]