Effect of barrel temperature and feed moisture on protein quality in pre-cooked Kabuli chickpea, sorghum, and maize flours

Impact of cooking on the protein quality of Russet potatoes

Despite being low in crude protein, on a fresh weight basis, given their overall contribution to the North American diet, potatoes contribute approximately 2%-4% of the population's protein intake. However, the quality of the protein remains ill-defined. To that end, Russet potatoes were secured and subjected to various cooking conditions (raw [control], boiled, baked, microwaved, and fried [3, 6, and 9 min]) to determine the impact of cooking method on protein quality, as determined by amino acid score (AAS) and indices of in vivo true fecal protein digestibility (TFPD%; rodent bioassay) and in vitro protein digestibility (pH-drop, pH-Stat, and simulated gastrointestinal digestion both static and dynamic). The AAS of raw Russet potatoes was 0.67 ± 0.01, with histidine being the limiting AA. Frying led to a significant reduction in the AAS, however, other cooking methods yielded similar results to the raw control. The TFPD% of raw potato was low (40.5% ± 3.9%) and was significantly enhanced to over 80% with all cooking methods. Similar patterns were observed with all in vitro measures, however, all methods yielded higher values for the raw control samples. Final protein digestibility-corrected AAS (PDCAAS; product of AAS and TFPD%) values ranged from 0.27 (raw) to a high of 0.57 (boiled), with cooked values being comparable to other plant-based protein sources, including grains, and some nuts and pulses. In vitro PDCAAS values followed similar trends. This study defined the protein quality of cooked Russet potatoes and provides data for use in defining the quality of total protein consumed in the North American diet.

Germinated chickpea-maize extrudates with high protein content and reduced starch digestibility

The objective of this study was to produce maize extrudates supplemented with germinated chickpea flour to increase the contents of resistant starch (RS) and protein. Six extrudates were formulated using maize grits (ME), germinated chickpea flour (GCE) and different blends of maize and 10%, 20%, 30%, or 40% of germinated chickpea flour (MGCE-10, MGCE-20, MGCE-30, or MGCE-40). Increase of RS was observed in the defatted samples due to germinated chickpea flour addition. In the nondefatted samples, the highest content of RS was observed in GCE followed by ME and the different MGCE. Interaction between fat, starch, and protein by improved intramolecular association was assessed by Fourier transform- infrared spectroscopy (FTIR). Amylose-lipid complexes in nondefatted samples increased the content of RS in comparison to defatted samples. The highest expansion index was obtained in MGCE-30 and MGCE-40. ME had the highest hardness and crispiness. Germinated chickpea flour increased the water absorption index (WAI), but reduced water solubility index (WSI) when it was combined with maize grits to produce extrudates. The in vitro protein digestibility (IVPD) was higher in the GCE and MGCE with more than 20% of germinated chickpea flour compared to ME. MGCE-20 and MGCE-30 showed the highest acceptability of the supplemented extrudates with 50% more protein than ME, a similar IVPD to that of GCE, and good functional characteristics. PRACTICAL APPLICATION: Combining maize and germinated chickpea flour is a good strategy to have a controlled digestibility of starch and increase the plant based protein content in healthier snacks.

Technological properties of chickpea (Cicer arietinum): Production of snacks and health benefits related to type-2 diabetes

Chickpea (Cicer arietinum) is one of the most consumed pulses worldwide (over 2.3 million tons enter the world market annually). Some chickpea components have shown, in preclinical and clinical studies, several health benefits, including antioxidant capacity, and antifungal, antibacterial, analgesic, anticancer, antiinflammatory, and hypocholesterolemic properties, as well as angiotensin I-converting enzyme inhibition. In the United States, chickpea is consumed mostly in the form of hummus. However, the development of new products with value-added bioactivity is creating new opportunities for research and food applications. Information about bioactive compounds and functional properties of chickpea ingredients in the development of new products is needed. The objective of this review was to summarize available scientific information, from the last 15 years, on chickpea production, consumption trends, applications in the food industry in the elaboration of plant-based snacks, and on its bioactive compounds related to type 2 diabetes (T2D). Areas of opportunity for future research and new applications of specific bioactive compounds as novel food ingredients are highlighted. Research is key to overcome the main processing obstacles and sensory challenges for the application of chickpea as ingredient in snack preparations. The use of chickpea bioactive compounds as ingredient in food products is also a promising area for accessibility of their health benefits, such as the management of T2D.

Effect of Extrusion Processing Conditions on the Phenolic Compound Content and Antioxidant Capacity of Sorghum (Sorghum bicolor (L.) Moench) Bran

Sorghum is a cereal with little use in human diet; however, this grain can provide several nutrients and, additionally, has a high content of phenolic compounds concentrated in bran, which could be beneficial to human health due to its high antioxidant capacity. However, these bioactive compounds are bound within the cell wall matrix; it is necessary to release these compounds to take advantage of their antioxidant properties. The extrusion process increases the accessibility of bound phenolic compounds, breaking their bonds from the bran matrix. The aim of this study was to determine the optimal extrusion conditions for maximizing the phenolic compound content and antioxidant capacity of sorghum bran extrudate. The extrusion process factors evaluated were feed moisture (FM) from 25 to 35% and the fourth extrusion zone temperature (T) in the range of 140-180 °C. Analysis of variance and response surface analysis were used in the evaluation. The prediction coefficient, (FM)², (T)² and their interaction (FM)(T) significantly affected the free total phenolic compounds. The antioxidant capacity of the free total phenolic compounds was significantly affected by (FM)² and (T)². The optimal extrusion conditions were FM = 30% and T = 160 °C, which provided free total phenolic compounds with a value of 7428.95 μg GAE/g (predicted value: 7810.90 μg GAE/g) and antioxidant capacity with a value of 14.12 μmol TE/g (predicted value: 14.85 μmol TE/g). Results confirmed that extrusion process optimization was useful to increase the content of phenolic compounds and improved the antioxidant capacity of sorghum bran.

Effect of the nixtamalization process on the protein bioaccessibility of white and red sorghum flours during in vitro gastrointestinal digestion

Protein bioaccessibility is a major concern in sorghum (Sorghum bicolor L. Moench) due to potential interactions with tannins affecting its nutritional value. Technological treatments such as boiling or alkaline cooking have been proposed to address this problem by reducing tannin-protein interactions. This research aimed to evaluate the impact of nixtamalization in the protein bioaccessibility from two sorghum varieties (red and white sorghum) during in vitro gastrointestinal digestion. Nixtamalization increased protein bioaccessibility in the non-digestible fraction (NDF) (5.26 and 26.31% for red and white sorghum, respectively). However, cooking showed a higher permeation speed of protein from red sorghum flours at the end of the intestinal incubation (9.42%). The SDS-PAGE profile of the digested fraction (DF) at 90 min of intestinal incubation indicated that, for red sorghum, cooking allows the formation of α and γ-kafirins while nixtamalization increase α-kafirin release. Principal Components Analysis (PCA) showed the association between nixtamalization and dissociation of δα kafirin complexes and increased protein content in the digestible fraction. In silico interactions indicated the highest biding energies for (+)-catechin and kafirin fractions (β-kafirin: -7.0 kcal/mol; γ-kafirin: -5.8 kcal/mol, and δ-kafirin: -6.8 kcal/mol), suggesting a minor influence of depolymerized proanthocyanidin fractions with sorghum proteins as a result of the nixtamalization process. In conclusion, nixtamalization increased the bioaccessibility of sorghum proteins, depolymerizing condensed tannins, and breaking protein-tannin complexes. Such technological process improves the nutrimental value of sorghum, supporting its inclusion in the human diet.