Reduced in vitro starch hydrolysis and in vivo glycemic effects after addition of soy presscake to corn tortillas.

BACKGROUND: Chronically elevated blood glucose leads to development of prediabetes and type 2 diabetes, as well as increased risk for heart and kidney disease and vision loss. For many, elevated blood glucose can be managed through diet and exercise. Consequently, the availability of foods that limit blood glucose elevation would aid in addressing this global problem. This paper investigated the effect of adding soy presscake (SP) to corn tortillas on starch hydrolysis in vitro as well as the glycemic responses elicited in vivo upon consumption of these modified tortillas. RESULTS: SP in corn tortillas decreased the rate and extent of starch hydrolysis in vitro. The in vivo glycemic index (GI) values decreased from 43 for corn control tortillas to 31 with 40% SP fortification. A high correlation (r = 0.9781) was found between the GI values from in vivo analysis and the area under the curve of starch hydrolysis in vitro. The best correlations (r > 0.96) between GI and degree of hydrolysis were found at 45-90 min of in vitro starch hydrolysis. CONCLUSIONS: Incorporating SP into corn-based tortillas lowers glycemic responses to them. In addition, in vitro starch hydrolysis could be used to estimate the GI values of food products and, in particular, the comparison of multiple items during food product development. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Plant extracts effectiveness to extend bison meat shelf life.

The effectiveness of plant extracts (0.05% rosemary and 0.08% oregano) to extend shelf life of bison strip loin steaks in terms of color stability and consumer acceptability was studied. Steaks treated with oregano presented lower oxygen consumption, higher metmyoglobin-reducing activity (MRA), decreased lipid oxidation, and provided a stable red color with less discoloration during the retail display period than the control and rosemary treated steaks (P < 0.05). Results from consumer sensory evaluation indicated that treated steaks under study were not significantly different from the control (P > 0.05) based on palatability attributes and acceptability. However, rosemary treated steaks were more desirable and palatable than their oregano counterparts (P < 0.05). Overall, plant extracts, particularly oregano, can improve color stability of bison steaks due to its antioxidants properties and ability to increase MRA capacity in fresh bison meat without posing any negative impact on its sensory attributes. PRACTICAL APPLICATION: This study will provide valuable information to the bison meat industry on how to offer a more consistent and acceptable product (in terms of palatability and color) to consumers using plant-based natural antioxidants, without diminishing the palatability of their products. This technology can offer two more days of shelf life in retail overwrap packaging, consequently, opening the possibility for the bison industry to expand its market with a potential to reduce retail losses due to poor color stability and early browning (that is, stock out, markdowns, and waste due to expired display life).

Characteristics of flavonol glycosides in bean (Phaseolus vulgaris L.) seed coats.

Seed coats of coloured dry beans contain biologically active compounds. Flavonol glycosides were identified from acetone extracts of seed coats of black beans, pinto beans, and red kidney beans and evaluated for antioxidant activity. High Performance Liquid Chromatography - Mass Spectrometry/Mass Spectrometry (HPLC-MS/MS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging capacity were used to measure flavonols and antioxidant capacity, respectively. The main flavonol glycosides in black beans were the 3-O-glycosides of kaempferol, quercetin and myricetin; pinto beans contained kaempferol 3-O-glycosides, while red kidney beans contained quercetin 3-O-glycoside and quercetin 3-O-rutinoside (rutin). A flavonol triglycoside was identified in dark red kidney bean. Despite differences in total flavonol content, extracts from Eclipse, (black bean) and Windbreaker (pinto bean) had the significantly higher antioxidant activities than other bean seed coats. Results suggest seed coats of Windbreaker and Eclipse may have potential as functional food ingredients, though benefits may not be simply due to flavonols.

Changes in levels of phytic acid, lectins and oxalates during soaking and cooking of Canadian pulses.

Raw and processed (soaked or cooked) seeds of peas, lentils, chickpeas, fava beans and common beans were studied for their contents of antinutritional factors (lectins, phytic acid, total and soluble oxalates), along with soybean as a control. Analysis of variance indicated that legume type, treatment and their interactive effects were significant on these antinutrients. The raw soybean seed was found to contain the highest levels of lectins (692.8 HU/mg), phytic acid (22.91 mg/g), total oxalate (370.5 mg/100 g) and soluble oxalate (200.7 mg/100 g) among all investigated seeds. Relatively high contents of lectins were detected in beans (87.69-88.59 HU/mg) and other pulses ranging from 2.73-11.07 HU/mg. Phytic acid in Canadian pulses varied slightly from 8.55-22.85 mg/g. Total oxalates were variable, ranging from 244.7-294.0 mg/100 g in peas, 168.6-289.1 mg/100 g in lentils, 241.5-291.4 mg/100 g in fava beans, 92.2-214.0 mg/100 g in chickpeas and 98.86-117.0 mg/100 g in common beans. Approximately 24-72% of total oxalate appeared to be soluble in all investigated pulses. Soaking the seeds in distilled water significantly decreased the contents of lectins (0.11-5.18%), total oxalate (17.40-51.89%) and soluble oxalate (26.66-56.29%), but had no impact on phytic acid. The cooking process was found to be more effective in reducing levels of all the investigated antinutritional factors, except phytic acid in common beans and soybean.

Changes in levels of enzyme inhibitors during soaking and cooking for pulses available in Canada.

The effects of processing (soaking and cooking) on enzyme inhibitors (α-amylase, trypsin and chymotrypsin inhibitors) in a range of pulses (4 peas, 9 lentils, 3 chickpeas, 2 faba beans and 4 beans) were investigated, using soybean as a control. Analysis of variance indicated that pulse type, treatment and their interaction had significant effects on levels of all enzyme inhibitors. Soybean contained the highest levels of trypsin inhibitory activity (TIA) and chymotrypsin inhibitory activity (CIA) among all seeds. α-Amylase inhibitory activity was absent from peas, lentils, chickpeas and faba beans, but was present in beans and soybean. TIA was found to be low in peas but high in beans. Beans contained relatively high CIA levels followed by chickpeas, lentils, peas and faba beans. Soaking markedly decreased the activity of enzyme inhibitors. Cooking of presoaked seeds was even more effective as greater reductions (78.7-100%) were observed for all pulses. The content of enzyme inhibitors in pulses varied widely, but levels of protease inhibitors were generally lower that those found in soybean. Processing, in particular heat treatments, drastically reduced these levels.

Influence of Added Soy Presscake and Soy Flour on Some Physical and Sensory Properties of Corn Tortillas.

Corn tortillas fortified with soybean presscake (SP) and defatted soy flour (SF) were studied and compared. Texture, including firmness and cohesiveness, and color, using a CIE L* a* b* , were determined instrumentally. Physical properties such as size, thickness, and rollability, were also investigated. A consumer acceptance test was conducted to evaluate the acceptance of tortillas at high levels of soy fortification (35% SF and 40% SP). Tortillas fortified with soy were found to be smaller and thicker with increased firmness and cohesiveness. Tortillas made with SF showed the poorest rollability, and were almost unrollable at high SF fortification levels (30% and 35%). Soy fortified tortillas were more red and yellow than control corn tortillas. In the consumer acceptance test, 40% SP and 35% SF had high overall acceptability scores (6 to 6.6 on a 9-point scale) based on all participants (n = 76). In addition, overall flavor and texture of both soy fortified corn tortillas scored above 6. Thus, while fortification with SP and SF had significant effects on tortilla size, thickness, firmness, cohesiveness, rollability, and color, these changes were acceptable to consumers.

Probing the molecular forces involved in binding of selected volatile flavour compounds to salt-extracted pea proteins.

Molecular interactions between heterologous classes of flavour compounds with salt-extracted pea protein isolates (PPIs) were determined using various bond disrupting agents followed by GC/MS analysis. Flavour bound by proteins decreased in the order: dibutyl disulfide>octanal>hexyl acetate>2-octanone=benzaldehyde. Benzaldehyde, 2-octanone and hexyl acetate interacted non-covalently with PPIs, whereas octanal bound PPIs via covalent and non-covalent forces. Dibutyl disulfide reacted with PPIs covalently, as its retention was not diminished by urea and guanidine hydrochloride. Using propylene glycol, H-bonding and ionic interactions were implicated for hexyl acetate, benzaldehyde, and 2-octanone. A protein-destabilising salt (Cl3CCOONa) reduced bindings for 2-octanone, hexyl acetate, and benzaldehyde; however, retention for octanal and dibutyl disulfide increased. Conversely, a protein-stabilising salt (Na2SO4) enhanced retention for benzaldehyde, 2-octanone, hexyl acetate and octanal. Formation of a volatile flavour by-product, 1-butanethiol, from dibutyl disulfide when PPIs were treated with dithiothreitol indicated occurrence of sulfhydryl-disulfide interchange reactions.

Comparison of Phytochemicals and Antioxidant Capacity in Three Bean Varieties Grown in Central Malawi.

The aims of the current work were: (1) to study the influence of variety and geographical production area on the total phenolic content, total anthocyanin content, total flavonoid content, total carotenoid content and antioxidant activity in bean varieties (Dimeta, Napirira and Nanyati) from different growing areas in central Malawi, and (2) to evaluate the possibility of establishing a classification based on the geographical areas of the growing regions. A total of 47 bean samples were collected from Makowe, Mphathi, Chuma-Chitsala and Khulungira Zone. These four locations were segregated based on altitude, latitude and longitude. Principal component and hierarchical cluster analysis were used to distinguish and classify among these samples. Significant differences (P < 0.05) in total phenolic content (2.92-4.97 mg/g), total anthocyanin content (14.52-152.31 µg/g), total flavonoid content (2.01-6.38 mg/g) and oxygen radical absorbance capacity (16.75-24.51 µmol/g) were found among the different sampled villages, showing a significant effect of the producing region on these parameters. The beans in Makowe had lower polyphenols than in other locations. Results of principal component analysis indicate that phytochemicals and antioxidant capacity could serve as parameters to establish a bean classification according to the geographical area of production.

Provitamin A potential of landrace orange maize variety (Zea mays L.) grown in different geographical locations of central Malawi.

The provitamin A potential of landrace orange maize from different locations (A, B, C and D) of central Malawi has been evaluated. Physicochemical compositions, color, total carotenoid content (TCC), carotenoid profiles, and oxygen radical absorbance capacity (ORAC) and 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging activity as antioxidant capacities of maize were determined. Color values of orange maize had correlations with ß-cryptoxanthin (r>0.36). TCC of white and orange maize averaged 2.12 and 59.5 mg/kg, respectively. Lutein was the most abundant carotenoid (47.8%) in orange maize, followed by zeaxanthin (24.2%), ß-carotene (16.4%) and ß-cryptoxanthin (11.6%). Location D showed the highest levels of lutein, zeaxanthin and antioxidant capacity. Provitamin A content of orange maize met the target level (15 µg/g) of biofortification. Retinol activity equivalent (RAE) from ß-cryptoxanthin and ß-carotene in orange maize averaged 81.73 µg/100g. In conclusion, orange maize has the potential to be a natural source of provitamin A.

Binding of carbonyl flavours to canola, pea and wheat proteins using GC/MS approach.

Interactions of homologous aldehydes (hexanal, heptanal, and octanal) and ketones (2-hexanone, 2-heptanone, and 2-octanone) to salt and alkaline-extracted canola and pea proteins and commercial wheat gluten were studied using GC/MS. Long-chain aldehyde flavours exhibited higher binding affinity, regardless of protein type and isolation method. Salt-extracted canola protein isolates (CPIs) revealed the highest binding capacity to all aldehydes followed by wheat gluten and salt-extracted pea protein isolates (PPIs), while binding of ketone flavours decreased in the order: PPIs>wheat gluten>CPIs. Two aldolisation products, 2-butyl-2-octenal and 2-pentyl-2-nonenal, were detected from the interactions between CPIs with hexanal and heptanal, respectively. Protein thermal behaviour in the presence of these compounds was analysed by differential scanning calorimeter, where decreased ΔH inferred potential conformational changes due to partial denaturation of PPIs. Compared to ketones, aldehyde flavours possessed much higher "unfolding capacity" (lower ΔH), which accounted for their higher binding affinities.

Incorporation of pulse flours of different particle size in relation to pita bread quality.

BACKGROUND: To increase pulse consumption, pita bread was fortified with pulse flours milled from green lentils, navy beans and pinto beans, which were ground to produce fine and coarse flours. Pita breads were prepared using composite flours containing pulse flours (25, 50, 75%) and wheat flour or 100% pulse flours and adjusting the amount of water required for mixing based on farinograph water absorption. Pita bread quality was evaluated according to diameter, pocket height, specific loaf volume, texture and crust colour. RESULTS: Blends made from pulse flours with coarse particle size showed higher rates of water absorption. All composite flours and 100% pulse flours produced pitas with pockets, confirming their suitability for this product. Crust colour of pitas was affected less by navy bean flour than by lentil flour. Pita breads made with pinto bean flour were superior in texture. Overall, navy and pinto bean flours appeared more suitable for pita bread. Flours with coarse particle sizes produced pitas with better colour and texture. Sensory parameters of pitas containing 25% coarse pinto or navy bean flour were as good as or better than those from the wheat control. CONCLUSION: Acceptable pita breads can be made using pulse flours, although the substitution level is limited to 25%.

Influence of added bean flour (Phaseolus vulgaris L.) on some physical and nutritional properties of wheat flour tortillas.

Composite flours containing 15%, 25%, or 35% of small red, black, pinto, or navy bean flours (BF) and wheat were made into tortillas. Dough rheology, firmness, cohesiveness, rollability, and some physical properties of tortillas were negatively affected as BF concentration increased regardless of bean cultivar. Nutritionally, all bean tortillas had significantly higher levels of crude protein, total phenols, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS(+)) in vitro antioxidant activity (AA) and antinutritional compounds such as phytic acid (PA) and trypsin inhibitors (TI) than the wheat control. Tortillas to which 35% of small red, pinto and black BF was added had the highest levels of phenols, which were significantly correlated with both DPPH (r=0.99) and ABTS(+) (r=0.99) AA. Compared to raw flours, PA and TI were reduced from 37.37% to 43.78% and from 50% to 66%, respectively, in the tortillas. Overall analysis indicated that tortillas with acceptable texture and improved nutritional profile were produced at 25% substitution.