In vitro gastrointestinal digestion of glabrous canaryseed proteins as affected by variety and thermal treatment

Effects of Genotype and Growing Year on the Nutritional Composition and Pasting Properties of Glabrous Canary Seed (Phalaris canariensis L.) Groat Flours

Canary seed flour is a new food ingredient that the United States Food and Drug Administration (FDA) and Health Canada recently granted Generally Regarded as Safe (GRAS) status. Stability in nutritional composition and functional properties is an essential characteristic of food ingredients for consistency in nutritional quality and performance in processing. This work assessed the effect of genotypic and environmental variation on the nutritional (protein, starch, amylose, oil, dietary fiber, minerals and fat-soluble vitamins) and pasting (as measured in viscosity (peak, trough, breakdown, final, and setback), peak time, and pasting temperatures) properties of Canary seed. The samples included four Canary seed varieties grown in randomized complete block design experiments at one location for two growing seasons. In general, the nutritional composition of Canary seed flour was not affected by genotype, growing year, and their interaction except for starch content, which was significantly affected by the growing year (p < 0.0001), and iron content, which was affected by genotypic variation (p < 0.0001). The pasting properties of Canary seed flour were significantly (p < 0.001) affected by both genotypic and growing year variation but not their interaction. Our results suggest that the food industry should measure starch and iron content prior to processing to ensure consistency in nutritional labeling. Also, for those applications where starch pasting properties are essential, the manufacturer should consider measuring the RVA pasting viscosities for every batch of raw material. The results have provided the baseline knowledge of which nutritional or functional properties of Canary seed flour can be improved through breeding and agronomy programs to ensure the reliability of Canary seed as an ingredient.

Effect of processing on in vitro digestibility (IVPD) of food proteins

Proteins are important macronutrients for the human body to grow and function throughout life. Although proteins are found in most foods, their very dissimilar digestibility must be taking into consideration when addressing the nutritional composition of a diet. This review presents a comprehensive summary of the in vitro digestibility of proteins from plants, milk, muscle, and egg. It is evident from this work that protein digestibility greatly varies among foods, this variability being dependent not only upon the protein source, but also the food matrix and the molecular interactions between proteins and other food components (food formulation), as well as the conditions during food processing and storage. Different approaches have been applied to assess in vitro protein digestibility (IVPD), varying in both the enzyme assay and quantification method used. In general, animal proteins tend to show higher IVPD. Harsh technological treatments tend to reduce IVPD, except for plant proteins, in which thermal degradation of anti-nutritional compounds results in improved IVPD. However, in order to improve the current knowledge about protein digestibility there is a vital need for understanding dependency on a protein source, molecular interaction, processing and formulation and relationships between. Such knowledge can be used to develop new food products with enhanced protein bioaccessibility.

Hairless canary seeds (Phalaris canariensis L.) as a potential source of antioxidant, antihypertensive, antidiabetic, and antiobesity biopeptides

Rising consumer concerns with synthetic drugs to treat non-communicable diseases (NCDs) have promoted a shift towards using natural biological active constituents that offer similar health benefits. Hairless canary seed (Phalaris canariensis L) is an emerging crop traditionally used in Mexico to treat NCDs. Peptides liberated during simulated digestion of canary seed protein are believed to be responsible for their biological activity; however, no studies have shown the effect of controlled protein hydrolysis using commercial proteases on canary seed protein’s biological activity. Therefore, this study aimed to explore the in vitro antihypertensive, antidiabetic, and anti-obesity activity of canary seed peptides derived from proteolysis with Alcalase®. Protein fractions were primarily composed of prolamins (54.07 ± 1.8%), glutelins (32.19 ± 3.18%), globulins (5.97 ± 0.52%) and albumins (5.97 ± 0.52%). The < 3 kDa and 3–10 kDa peptide fractions showed the highest inhibition capacity (p < 0.05) towards angiotensin-converting enzyme (IC50= 0.028–0.032 mg/mL) lipase (IC50= 2.15–2.27 mg/mL), α-glucosidase (IC50= 0.82–1.15 mg/mL), and dipeptidyl-peptidase-IV (IC50= 1.27–1.60 mg/mL). Additionally, these peptide fractions showed high antioxidant activity against DPPH (134.22–150.66 μmol TE/mg) and ABTS (520.92–813.33 μmol TE/mg). These results provide an insight into the potential development of functional foods using commercial enzymatic hydrolysis of canary seed proteins for treating hypertension, type-2 diabetes, and obesity.

Hairless Canaryseed: A Novel Cereal with Health Promoting Potential

Glabrous canaryseeds were recently approved for human consumption as a novel cereal grain in Canada and the United States. Previously, canaryseeds were exclusively used as birdseed due to the presence of carcinogenic silica fibers; therefore the nutritional value of the seeds has been seriously overlooked. Two cultivars of glabrous canaryseeds (yellow and brown) were created from the hairy varieties. They are high in protein compared to other cereal grains, and contain high amounts of tryptophan, an amino acid normally lacking in cereals, and are gluten-free. Bioactive peptides of canaryseeds produced by in vitro gastrointestinal digestion have shown antioxidant, antidiabetic, and antihypertensive activity. The seeds contain other constituents with health promoting effects, including unsaturated fatty acids, minerals, and phytochemicals. Anti-nutritional components in the seeds are comparable to other cereal grains. Because of their beneficial health effects, canaryseeds should be regarded as a healthy food and have immense potential as a functional food and ingredient. Further research is required to determine additional bioactive peptide activity and capacity, as well as differences between the yellow and brown cultivars.

Antioxidant and Antihypertensive Potential of Protein Fractions from Flour and Milk Substitutes from Canary Seeds (Phalaris canariensis L.)

Canary seed (Phalaris canariensis) is used to feed birds but it has been recently considered a promising cereal with nutraceutical potential for humans. The aim of this work was to analyze the protein fractions from canary seed flour and from milk substitutes (prepared by soaking the seeds in water 12 and 24 h), and to evaluate antioxidant and antihypertensive capacity of peptides obtained after in vitro digestion. Prolamins were the major protein fraction, followed by glutelins. After digestion, albumins and prolamins fractions from milks presented higher levels of peptides than flour, globulins showed more peptides in flour and glutelins were found in similar concentrations in all samples; 24 h milk prolamins had the highest concentration of peptides. Purification by high performance liquid chromatography (HPLC), sequencing of peptides, in vitro antioxidant ABTS (2,2'-azino-bis, 3-ethylbenzothiazoline-6-sulphonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays, and antihypertensive capacity (angiotensin converting enzyme (ACE) assay), indicated that peptides from canary seed prolamins were the most efficient compounds with antioxidant and antihypertensive activity. Canary seeds may be considered an accessible and cheap source to prepare milk substitutes with high contents of bioactive peptides with remarkable functional properties to promote better human health and healthy ageing.

In vitro digestibility, protein composition and techno-functional properties of Saskatchewan grown yellow field peas (Pisum sativum L.) as affected by processing

Saskatchewan grown yellow field pea was subjected to different processing conditions including dehulling, micronization, roasting, conventional/microwave cooking, germination, and combined germination and conventional cooking/roasting. Their nutritional and antinutritional compositions, functional properties, microstructure, thermal properties, in vitro protein and starch digestibility, and protein composition were studied. Processed field peas including conventional cooked yellow peas (CCYP), microwave cooked yellow peas (MCYP), germinated-conventional cooked yellow peas (GCCYP), and germinated-roasted yellow peas (GRYP) exhibited the significantly higher in vitro protein digestibility (IVPD), which was in accordance with their significantly lower trypsin inhibitor activity and tannin content. The SDS-PAGE and size exclusion HPLC profiles of untreated pea proteins and their hydrolysates also confirmed the IVPD result that these four treatments facilitated the hydrolysis of pea proteins to a greater extent. The CCYP, MCYP, GCCYP, and GRYP also exhibited significantly higher starch digestibility which was supported by their lower onset (To), peak (Tp), and conclusion (Tc) temperatures obtained from DSC thermogram, their lower pasting properties and starch damage results, as well as their distinguished amorphous flakes' configuration observed on the scanning electron microscopic image. LC/ESI-MS/MS analysis following in-gel digests of SDS-PAGE separated proteins allowed detailed compositional characterization of pea proteins. The present study would provide fundamental information to help to better understand the functionality of field peas as ingredients, and particularly in regards to agri-food industry to improve the process efficiency of field peas with enhanced nutritional and techno-functional qualities.

Digestibility and structural properties of thermal and high hydrostatic pressure treated sweet potato (Ipomoea batatas L.) protein

This study assessed the effects of thermal (40, 60, 80, 100 and 127 °C) and high hydrostatic pressure (HHP, 200, 400 and 600 MPa) treatments on the in vitro digestibility and structural properties of sweet potato protein (SPP). The results showed that the in vitro digestibility of SPP increased significantly with increasing heating temperature and heating time (0-60 min), while HHP treatment had little or no effect. Native SPP denaturation temperature (T d ) and enthalpy change (ΔH) were 89.0 °C and 9.6 J/g, respectively. Thermal and HHP treated SPP had T d of 84.6-88.9 °C and 86.4-87.6 °C, respectively. ΔH of thermal treated SPP was 3.6-6.4 J/g, while that of HHP treated SPP was 5.9-7.8 J/g. The differential scanning calorimetry (DSC) results demonstrated that HHP and thermal treatments both significantly reduced SPP thermodynamic stability. Circular dichroism analyses revealed that native SPP contains α-helixes, β-sheets and random coils (4.3, 48.0 and 47.7%, respectively). After thermal treatment at 127 °C for 20 min, the content of α-helixes and turns increased significantly (13.2 and 27.6%, respectively), whereas the content of β-sheets decreased significantly (12.3%). In contrast, HHP treatment increased the content of β-sheets, but decreased the content of random coils. This study suggested that the SPP structure changes might be the main reason affecting the in vitro digestibility of SPP, and thermal treatment was more effective at changing SPP secondary structures and improving in vitro SPP digestibility than HHP treatment.