A current review of structure, functional properties, and industrial applications of pulse starches for value-added utilization.

Pulse crops have received growing attention from the agri-food sector because they can provide advantageous health benefits and offer a promising source of starch and protein. Pea, lentil, and faba bean are the three leading pulse crops utilized for extracting protein concentrate/isolate in food industry, which simultaneously generates a rising volume of pulse starch as a co-product. Pulse starch can be fractionated from seeds using dry and wet methods. Compared with most commercial starches, pea, lentil, and faba bean starches have relatively high amylose contents, longer amylopectin branch chains, and characteristic C-type polymorphic arrangement in the granules. The described molecular and granular structures of the pulse starches impart unique functional attributes, including high final viscosity during pasting, strong gelling property, and relatively low digestibility in a granular form. Starch isolated from wrinkled pea-a high-amylose mutant of this pulse crop-possesses an even higher amylose content and longer branch chains of amylopectin than smooth pea, lentil, and faba bean starches, which make the physicochemical properties and digestibility of the former distinctively different from those of common pulse starches. The special functional properties of pulse starches promote their applications in food, feed, bioplastic and other industrial products, which can be further expanded by modifying them through chemical, physical and/or enzymatic approaches. Future research directions to increase the fractionation efficiency, improve the physicochemical properties, and enhance the industrial utilization of pulse starches have also been proposed. The comprehensive information covered in this review will be beneficial for the pulse industry to develop effective strategies to generate value from pulse starch.

Evaluation of pasting and gelling properties of commercial flours under high heating temperatures using Rapid Visco Analyzer 4800.

In this study, pasting and gelling behaviors of flours were investigated at heating temperatures of 95-140 °C. Overall, both peak and breakdown viscosities of the flours were positively correlated with starch contents (p < 0.01) but inversely correlated with protein (p < 0.01) and fiber contents (p < 0.05) at 95-140 °C. When the heating temperature increased, pasting temperatures and peak viscosities of most waxy and normal flours largely remained the same, but their holding strengths and final viscosities gradually decreased. However, pulse and high-amylose maize flours required a holding temperature above 95 °C to achieve the highest peak and final viscosities. Normal maize and pulse flours formed hard gels after cooking at 120 °C, and high-amylose maize flour developed the firmest gel after cooking at 140 °C. Chemical compositions, particle sizes, and thermal properties of the studied flours influenced their pasting and gelling properties to certain levels under the different heating temperatures.

Development, structure and in vitro digestibility of type 3 resistant starch from acid-thinned and debranched pea and normal maize starches.

Type 3 resistant starch (RS3) was developed from native pea starch through acid thinning, debranching and recrystallization, and the resultant pea RS3 was then characterized and compared with that generated from native normal maize starch. Starting from the respective native starches, the modification method yielded 68.1% of RS3 from pea and 59.6% from normal maize. The particles of pea and normal maize RS3 showed a coarse surface and irregular shapes and sizes. Both pea and normal maize RS3 displayed the B-type X-ray diffraction pattern, with 41.0% and 37.7% relative crystallinity, respectively. In vitro starch digestibility assay revealed that pea RS3 - in both uncooked and cooked states - was less digestible by amylolytic enzymes than normal maize RS3 because the former possessed double-helical crystallites of a more compact structure. The information presented in the study is valuable for the development of RS ingredient from pea starch for food applications.

Characteristics of pea, lentil and faba bean starches isolated from air-classified flours in comparison with commercial starches.

This study aimed to isolate starches of a high purity from starch-rich pea, lentil and faba bean flours and to characterize and compare the isolated starches with important commercial starches. Isolated pulse starches had a purity of 94.8-97.9% and contained only 0.9-1.1% damaged starch. The isolated pulse starches showed amylose contents and amylopectin branch-chain-length distributions similar to those of commercial pea starch. Therefore, the granular morphologies, crystalline structure, thermal properties, pasting properties, gelling ability and in vitro digestibility of the isolated pulse starches were comparable to those of commercial pea starch but different from those of commercial maize and tapioca starches. The desirable functionality of the pulse starches (e.g., strong gelling ability) renders them suitable for some specific industrial applications, and further modifications can be utilized to enhance their functionality for broader use. This research provided the fundamental knowledge required for future efforts to promote value-added utilization of pulse starches.