Nutritional value of cooked beans (Phaseolus vulgaris) and their isolated major protein fractions

The digestibility and nutritional properties of whole cooked beans (Phaseolus vulgaris L) and their isolated and cooked major protein fractions were evaluated in rats. Isolated globulin GI was highly digestible (89.5%) but had a low NPR value (1.51). The albumins and glutelins exhibited intermediate digestibilities (79.1 and 73.2%) and a biological utilisation NPR of 3.18 and 2.91, respectively, 30% lower than casein. Whole beans exhibited the poorest digestibility (62.8%) with a faecal excretion of more than 30% of the ingested nitrogen and an intermediate NPR of 2.27. There was a direct relation between the amount of ingested dietary fibre and dry matter and N excretion. Enrichment of whole beans with the isolated albumin fraction, rich as it is in sulphur amino acids, did not improve NPR value. Dry beans apparently contain components producing undigestible protein complexes which affect amino acid availability and increase endogenous nitrogen excretion.     

Protein quality and energy density of green peas as influenced by seed size and time of harvest

Green peas (Pisum sativum L) were harvested at three different time points—3 days apart—and subsequently sorted into four fractions according to seed size (diameter > 10.2 mm; 10.2–8.75 mm; 8.75–8.2 mm and 8.2–6.0 mm). Three varieties from two years were investigated. The study comprised a total of 31 green pea samples. The average protein content of the samples was 276 g kg^?1 DM with relatively low variation (SE = 5.7). Protein content was highest in the smallest seeds. The average energy content was 18.6 MJ kg^?1DM. Dietary fibre content was 226 g kg^?1 DM, the major part (77%) as insoluble fibre. Seeds of early harvest and seeds with the smallest diameter had the lowest fibre (IDF and TDF) content and at the same time the highest energy digestibility. The average energy digestibility was 83.2%. Protein digestibility was relatively high (average 92.1%), while biological value (BV) and net protein utilisation (NPU) were moderate to low (60.6% and 55.8% respectively) due to low contents of the essential amino acids (g per 16 g N), especially tryptophan, methionine + cystine and lysine. Contents of lysine, tryptophan and methionine + cystine were more than 20% higher in the smallest seeds compared to the larger seeds. Similar differences were observed in seeds of late harvest as compared with seeds of early harvest. Correlation coefficients revealed a strong positive correlation between lysine, tryptophan and methionine + cystine content and the biological value of green pea protein. The three varieties investigated showed no differences in the chemical parameters although small differences in BV and NPU were observed.     

Influence of natural and controlled fermentations on α-galactosides, antinutrients and protein digestibility of beans (Phaseolus vulgaris L.)

The influence of natural fermentation (NF) and controlled fermentation (CF) in diminishing the content of antinutrients, α‐galactosides and increments in in vitro protein digestibility was investigated. The dry bean (Phaseolus vulgaris) flour was the substrate used in this research study. A decrease in raffinose oligosaccharide, antinutritional components and pH was observed in both types of fermentation. The natural lactic fermentation of ground beans produced significant increase (P < 0.05) in protein digestibility. For all varieties of beans, raffinose concentration reduced significantly to an undetectable level after 96 h of NF. CF did not have any significant effect on the reduction of the α‐galactosides content of the flours during fermentation. NF is an inexpensive method by which consumers can obtain good‐quality protein. Both types of fermentation diminish antinutrients and improve the nutritional value of the bean flour, and indicate the potential to use bean flour as an ingredient for fabricated foods.     

Chemical composition,in vitro starch digestibility and amino acid analysis of a underexplored kidney bean (Phaseolus vulgaris. L.) grown in Chongqing,China

Chemical composition, mineral analysis, in vitro starch digestibility, and amino acid analysis of a kidney bean (Phaseolus vulgaris. L.), grown in Chongqing, China, were carried out in 2011. The results showed that the bean flour contained low reducing sugar (0.79%) and fat (2.72%), but high protein (24.8%) and starch (44.84%). Mineral analysis indicated high Mg and Ca contents with low Na/K ratio (0.04). The proportions of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) were 39.64%, 41.46% and 18.90% respectively. And the variation in their proportions, along with prolonged heating time, showed increase in RDS, and decrease in SDS and RS, but the SDS + RS amount can still account for major parts (51.63%) of the total starch after a 90‐min pre‐cooking. Comparing the amino acid contents of the bean sample with recommended profile FAO/WHO/UNU (1985), the results fulfil the standard except threonine and lysine, whose contents are slightly lower than the requirements (0.93 and 0.85).     

Chemical analysis of French beans (Phaseolus vulgaris L.) by headspace solid phase microextraction (HS-SPME) and simultaneous distillation/extraction (SDE)

Headspace Solid Phase Microextraction (HS-SPME) involving divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibre and simultaneous distillation/extraction (SDE) techniques were applied to study the volatile and semi volatile compounds of thawed and cooked Phaseolus vulgaris L. A total of 104 compounds were detected by GC and GC/MS. Thereof, 76 compounds were identified for the first time in this species. The major differences between HS-SPME and SDE were found in the content of identified alcohols (23.62% SDE versus 62.20% SPME), terpenoids (39.15% SDE versus 2.45% SPME), heterocyclic compounds (13.78% SDE versus 1.21% SPME), hydrocarbons (2.22% SDE versus 13.87% SPME) and esters (0.98% SDE versus 12.98% SPME). The SPME technique was found to be useful for rapid and routine quality controls of thawed French beans, while SDE is favourable to study the entire set of flavour volatiles in the corresponding cooked samples.