Seed treatments affect milling properties and flour quality of black beans ( Phaseolus vulgaris L.)

Modification of physicochemical, functional properties, and digestibility of macronutrients in common bean (Phaseolus vulgaris L.) flours by different thermally treated whole seeds

The utilization of beans (Phaseolus vulgaris L.) is hindered by unpleasant flavors, low macronutrients digestibility, and long cooking time. The pre-thermally treated beans can overcome these limitations. Therefore, the effect of thermal methods (moist-heat and dry-heat) and bean market classes (black, navy, kidney, and pinto) on functional properties and digestibility of bean flours were compared to raw counterparts. Within bean class, moist-heated samples showed increased water-holding capacities of 2.54-2.87 g H₂O/g sample and starch/protein digestibility whereas dry-heated samples showed enhanced flavor profile and increased oil-holding capacities of 1.04-1.14 g oil/g sample. Among bean classes, moist-heated kidney bean flour showed the highest water-holding capacity of 2.87 g H₂O/g sample and starch/protein digestibility while dry-heated pinto bean flour had the highest oil-holding capacity of 1.14 g oil/g sample. The current result may provide a basis for the development of pre-thermally treated legume flours and facilitate their applications.

Enzyme pre-milling treatments improved milling performance of chickpeas by targeting mechanisms of seed coat and cotyledon adhesion with various effects on dhal quality

BACKGROUND

Dehulling and splitting are important elements of the milling process to produce dhal from pulses. However, grain that is difficult-to-mill because of tightly adhered seed coats or cotyledons that resist separation makes it difficult to achieve high quality dhal. Milling yields are reduced, energy inputs into the milling process are increased, and the resulting dhal can be of poorer quality, chipped or abraded.

RESULTS

Eight enzyme pre-treatments were chosen based on the hypothesised mechanisms of seed coat and cotyledon adhesion established previously. Using a difficult-to-mill chickpea (Cicer arietinum L.) genotype, we examined the effects of these pre-treatments, over time, on laboratory-scale milling performance and dhal quality. We pioneered a texture analyser method to measure the flex of the cotyledons and the force required to cleave the cotyledons. The enzyme-induced changes ranged from negative (tough seed coat, weight loss, deleterious colour and texture, increased visual damage to cotyledons and increased kibble loss, concave cotyledons, increased flex, and changes in taste) to positive (brittle seed coat, increased seed volume, improved dehulling efficiency and splitting yield, reduced cotyledon cleavage force, and acceptable dhal quality and taste).

CONCLUSION

All pre-treatments improved milling performance compared to milling the raw seed, although there was considerable variation between them. Two pre-treatments showed no improvement in milling yields compared to the water control, and several pre-treatments resulted in unacceptable qualities. Three pre-treatments, endo-polygalacturonanase, α-galactosidase and cellulase, show potential for commercial milling applications and could assist pulse millers globally to achieve high quality dhal at the same time as minimising milling effort. © 2021 Society of Chemical Industry.