Molecular structure characteristics, functional parameters andin vitroprotein digestion of pressure-cooked soya bean flours with different amounts of water

Optimization of Soybean Protein Extraction Using By-Products from NaCl Electrolysis as an Application of the Industrial Symbiosis Concept

Defatted soybean flour is generated during the oil extraction process of soybean, and it has a protein content of ~50%. On the other hand, an alkaline solution of NaOH is produced during the electrolysis process of NaCl in a novel method used to make a potent disinfectant/antiseptic (HOCl). In the present work, we suggest using these two products to produce soy protein isolate (SPI), aiming to create an industrial symbiosis. A Box–Behnken experimental design was executed, and a surface response analysis was performed to optimize temperature, alkaline solution, and time used for SPI extraction. The SPI produced at optimal conditions was then characterized. The experimental results fit well with a second-order polynomial equation that could predict 93.15% of the variability under a combination of 70 °C, alkaline solution 3 (pH 12.68), and 44.7 min of the process. The model predicts a 49.79% extraction yield, and when tested, we obtained 48.30% within the confidence interval (46.66–52.93%). The obtained SPI was comparable in content and structure with a commercial SPI by molecular weight and molecular spectroscopy characterization. Finally, the urease activity (UA) test was negative, indicating no activity for trypsin inhibitor. Based on the functional properties, the SPI is suitable for food applications.

Effect of processing on in vitro digestibility (IVPD) of food proteins

Proteins are important macronutrients for the human body to grow and function throughout life. Although proteins are found in most foods, their very dissimilar digestibility must be taking into consideration when addressing the nutritional composition of a diet. This review presents a comprehensive summary of the in vitro digestibility of proteins from plants, milk, muscle, and egg. It is evident from this work that protein digestibility greatly varies among foods, this variability being dependent not only upon the protein source, but also the food matrix and the molecular interactions between proteins and other food components (food formulation), as well as the conditions during food processing and storage. Different approaches have been applied to assess in vitro protein digestibility (IVPD), varying in both the enzyme assay and quantification method used. In general, animal proteins tend to show higher IVPD. Harsh technological treatments tend to reduce IVPD, except for plant proteins, in which thermal degradation of anti-nutritional compounds results in improved IVPD. However, in order to improve the current knowledge about protein digestibility there is a vital need for understanding dependency on a protein source, molecular interaction, processing and formulation and relationships between. Such knowledge can be used to develop new food products with enhanced protein bioaccessibility.

Effects of heat treatment under low moisture conditions on the protein and oil in soybean seeds

The effects of autoclave and microwave heating on the protein and oil in soybean seeds were investigated under low moisture conditions. The nitrogen solubility index (NSI) decreased on heating. The reduction in the NSI was accompanied by an increase in the size and deformation of the oil bodies in the cellular tissue of soybean seeds. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that lipoxygenase was susceptible to heat denaturation, but 7S and 11S globulins were only partially denatured. The partial denaturation of the proteins was confirmed by Fourier transform infrared spectroscopy measurements. The ratio of oil to protein peaks increased with increasing heating, suggesting the exudation of oil to the surface or outside of oil bodies. Microwave heating is more efficient in changing the oil distribution in soybean seeds than autoclave heating. On the other hand, the degree of protein denaturation is lower after microwave heating.

Diversity in protein secondary structure, molecular weight, mineral and amino acid composition of lentil and horse gram germplasm

Lentil and horse gram germplasm was assessed for variety in seed and flour properties. Horsegram grains showed higher a* and b* and lower L* values as compared to lentil grains indicating lentil grains were lighter in color as compared to horse gram. Both the pulses showed significant differential accumulation of minerals. Flours from horse gram lines showed higher Mn, K, Mg, Na, Zn and Ca content and lower Cu and Fe content as compared to lentil lines. Polypeptide of 42 kDa was present in IC94636 and IC139555 only and 35 kDa PP subunit was absent in all the horse gram lines except IC94636. Major polymorphism among lentil lines was observed in 10, 35-37 and 55-49 kDa PP subunits. Amount of β-sheets and β-turns was the highest whereas that of antiparallel β-sheets was the lowest. NIC17550, NIC17551 and NIC17552 showed higher content of antiparallel β-sheets and random coils among lentil lines. PL1 showed the highest portion of α-helixes and β-turns whereas PL57 showed the highest proportion of β-sheets among lentil lines. Lentil flours showed higher proportion of aspartic acid, glutamic acid, asparagine, serine, citrulline and serine and lower proportion of histidine, threonine, GABA, tyrosine and cystine as compared to horse gram.

Deodorization of Arthrospira platensis biomass for further scale-up food applications

BACKGROUND

Given the importance of A. platensis as a potential food protein source, we describe an affordable deodorization process that does not significantly affect the nutritional value of algae biomass.

RESULTS

Ethanol, acetone or hexane were used to deodorize algae biomass and then to identify the profile of volatile compounds associated with its distinctive odor. Sensorial characteristics were improved in the biomass cake after the proposed solvent extraction. Panelists identified the ethanolic extract with the most pronounced algae-related odor. Gas chromatography-mass spectrometry analysis showed that a mixture of 20 different compounds derived from fatty acids and amino acids contributed to the characteristic smell of A. platensis biomass. The results of the present study show that the ethanol solvent-free A. platensis biomass contained > 600 g kg^-1 protein, < 10 g kg^-1  crude fat and > 65% in vitro protein digestibility, similar to the original biomass. The Fourier transform infrared spectroscopy secondary protein structure was comparable among samples, indicating that the only change after ethanol extraction was a reduction of the algae smell.

CONCLUSION

The various extraction procedures investigated in the present study were effective in deodorizing the algae biomass. The most effective protocol was the removal of odoriferous compounds with ethanol. This particular procedure yielded an algae biomass with an improved sensorial traits. The results of the present study should help with the identification of odoriferous compounds derived from fatty acids, pigments and proteins associated with A. platensis. © 2017 Society of Chemical Industry.