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In order to determine the impact of fermentation on protein quality, pea protein concentrate (PPC) was fermented with for 11 h and total phenol and tannin contents, protease inhibitor activity, amino acid composition and protein digestibility were analyzed. Phenol levels, expressed as catechin equivalents (CE), increased on dry mass basis from 2.5 at 0 h to 4.9 mg CE per 1 g of PPC at 11 h. Tannin content rose from 0.14 at 0 h to a maximum of 0.96 mg CE per 1 g of PPC after 5 h, and thereafter declined to 0.79 mg/g after 11 h. After 9 h of fermentation trypsin inhibitor activity decreased, however, at all other fermentation times similar levels to the PPC at time 0 h were produced. Chymotrypsin inhibitor activity decreased from 3.7 to 1.1 chymotrypsin inhibitory units (CIU) per mg following 11 h of fermentation. Protein digestibility reached a maximum (87.4%) after 5 h of fermentation, however, the sulfur amino acid score was reduced from 0.84 at 0 h to 0.66 at 11 h. This reduction in sulfur content altered the protein digestibility-corrected amino acid score from 67.0% at 0 h to 54.6% at 11 h. These data suggest that while fermentation is a viable method of reducing certain non-nutritive compounds in pea protein concentrate, selection of an alternative bacterium which metabolises sulfur amino acids to a lesser extent than should be considered.

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Surface characteristics and functional attributes of protein isolates prepared from different pea cultivars using isoelectric precipitation were investigated. Protein levels of isolates ranged from 81-89% with isoelectric points occurring between pH 4.7-4.9. Surface hydrophobicity values differed among cultivars with CDC Dundurn and CDC Striker isolates having the lowest and highest values, respectively. Protein solubility values at pH 7.0 varied with MFR042 and CDC Dundurn isolates displaying the lowest (approximately 54%) and highest (approximately 76%) values, respectively. No significant (p>0.05) differences existed between cultivar isolates for water hydration and oil holding capacity values. Cooper and CDC Dundurn isolates had significantly (p<0.05) lower emulsifying activity indices (EAI) (approximately 31-33 m 2 /g) than the other cultivars. Emulsifying stability index values were all similar. EAI values were positively correlated with surface hydrophobicity values and negatively correlated with solubility values. Varietal differences for the functional attributes of solubility and emulsification were identified.

The pressing need for protein supply growth gives rise to alternative protein sources, such as insect proteins. Commercial cricket and mealworm powders were examined for their protein quality, surface charge and functional attributes. Both insect powders had similar proximate compositions with protein and ash contents of * 66% db (dry weight basis) and 5% db, respectively, however cricket powder contained more lipid (16.1%, db) than mealworm powder (13.7%, db). Mealworm protein had an amino acid score of 0.71 and was first limiting in lysine, whereas cricket protein was first limiting in tryptophan with an amino acid score of 0.85. In vitro protein digestibility values of 75.7% and 76.2%, and in vitro protein digestibility corrected amino acid scores of 0.54 and 0.65, were obtained for mealworm and cricket powders, respectively. Zeta potential measurements gave isoelectric points near pH 3.9 for both insect powders. Mealworm and cricket powders had water hydration capacities of 1.62 g/g and 1.76 g/g, respectively, and oil holding capacities of 1.58 g/g and 1.42 g/g, respectively. Both insect proteins had low solubility (22-30%) at all pHs (3.0, 5.0, and 7.0) measured. Cricket powder had a foaming capacity of 82% and foam stability of 86%, whereas mealworm powder was non-foaming. Values for commercial pea and faba bean protein concentrates were reported for comparative purposes. The insect proteins had similar protein quality as the pulse proteins and had higher solubility at pH 5.0 but were much less soluble at pH 7.0.

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stability, oil-holding capacity and water hydration capacity were insignificant. As for the protein concentrates' solubility, the effect of genotype and the interaction between genotype and environment were significant, with values of solubility ranging between 82.3 and 88.0 %.