Pyropia columbina phycocolloids as microencapsulating material improve bioaccessibility of brewers’ spent grain peptides with ACE-I inhibitory activity

The effects of wall hydrocolloids on delivery and bioaccessibility of encapsulated brewers’ spent grain ACE-I inhibitory peptides after simulated gastrointestinal digestion were assessed. Microencapsulation of peptides was carried out by spray drying using locust bean gum, P. columbina phycocolloids, or its mixtures as wall materials. Microcapsules presented round external surfaces with some concavities, negative surface charge and encapsulation efficiencies higher than 90%. The incorporation of phycocolloids to formulations increased the encapsulation efficiency, negative surface charge and resistance against digestive enzymes of microcapsules. Encapsulated peptides with P. columbina phycocolloids showed lower IC₅₀ value of ACE-I inhibition than un-encapsulated peptides (2.4 ± 0.2 vs. 7.2 ± 0.3 mg mL⁻¹ protein), but higher than that obtained for hydrolysate (1.5 ± 0.2 mg mL⁻¹ protein), indicating a 75% protection of bioactivity. Electrostatic and hydrophobic interactions between P. columbina phycocolloids and brewers’ spent grain peptides could be implicated in the protection of peptides during gastrointestinal digestion.     

Effect of preincubation of sorghum flour with enzymes on the digestibility of sorghum gruel

A low-tannin sorghum cultivar M-35-1 was used in this study. Sorghum was germinated for 6 days and protease and amylase activities were measured every 24 h. Results showed that the 5th day germinated sorghum had a higher protease activity and a lower amylase activity. Sorghum flour was incubated for 30 min with the extract from germinated sorghum or with 0.01, 0.05 or 0.1 mg ml⁻¹ papain or trypsin prior to cooking in water. Results showed increase in in vitro protein digestibility (IVPD) with the 5th day germination extract. Pretreatment of sorghum flour with small amounts of papain or trypsin (0.01 mg ml⁻¹) improved the IVPD without affecting the paste viscosity, whereas the germinated sorghum extract led to very low paste viscosity. ©     

Selective separation and characterisation of dual ACE and DPP-IV inhibitory peptides from rainbow trout (Oncorhynchus mykiss) protein hydrolysates

Microwave pretreatment and hydrolysis were applied to rainbow trout (Oncorhynchus mykiss) by-products to produce bioactive peptides with dual in vitro angiotensin-I converting enzyme (ACE) and dipeptidyl-peptidase IV (DPP-IV) inhibitory activities. Peptides were fractionated using the single step electrodialysis with ultrafiltration membrane (EDUF). Concentration of cationic peptides (CP) increased in the recovery solution, reaching 125 μg mL⁻¹ after a 4-h treatment with migration rate of 15.68 ± 2.98 g m⁻² h. CP fractions displayed ACE and DPP-IV I inhibitory properties, with IC₅₀ values of 0.0036 mg mL⁻¹ and 1.23 mg mL⁻¹ respectively. The bioactivity was attributed to the low molecular weight peptides (300–500 Da) recovered. CP exhibited non-competitive inhibition patterns for ACE and DPP-IV, which were dose dependent. These results showed that bioactive peptides can successfully be separated from complex hydrolysate mixtures by EDUF. The fractionated peptides can serve as potential functional food ingredients or nutraceuticals for the management of hypertension and diabetes.     

Novel β-casein derived antioxidant and ACE-inhibitory active peptide from camel milk fermented by Leuconostoc lactis PTCC1899: Identification and molecular docking

Antioxidant and angiotensin-I converting enzyme inhibitory (ACE-I) activities of bioactive peptide fractions from camel milk fermented by Leuconostoc lactis PTCC 1899 were assessed. The fraction <3 kDa obtained from ultrafiltration showed ACE-I (IC₅₀ = 1.61 ± 0.18 mg mL⁻¹) and ABTS radical scavenging (1883.39 μm TE mg⁻¹ protein) activities and was purified through RP-HPLC. The active peptide, MVPYPQR, with antioxidant (8933.05 μm TE mg⁻¹ peptide) and ACE-I (IC₅₀ = 30 μm) activities was identified. To investigate the ACE-I mechanism of the purified peptide the docking study was performed. The presence of hydrogen bond between Gln 162 (S'1 pocket of ACE) and Arg in the C terminal of the peptide was identified and the peptide could distort the Zn²⁺ tetrahedral geometry of the enzyme. This study showed the ability of Leuc. lactis to produce a novel and safe functional food by hydrolysing the milk proteins during the fermentation.     

Amaranth functional cookies exert potential antithrombotic and antihypertensive activities

In this study, amaranth flour was used as an ingredient to prepare gluten-free cookies. The production process and attributes of amaranth cookies were characterised, and the potential use of amaranth flour as a functional ingredient was analysed. Cookies exhibited a non-uniform reddish brown colour and a cookie factor ratio of 4.5 ± 0.6. Storage studies indicated that after 3 weeks at room temperature cookies presented slight variations in the texture. Simulated gastrointestinal digestion of this product was able to release peptides capable of exerting potential antithrombotic and antihypertensive activities, IC₅₀ values of 0.22 ± 0.04 and 0.23 ± 0.03 mg mL⁻¹ protein, respectively. This work demonstrates for the first time that food made with amaranth flour exerts potential antithrombotic and antihypertensive activity. In conclusion, these amaranth cookies could be an alternative way of incorporating potentially health beneficial products for people who choose a conscious diet, including coeliac or vegan consumers.     

Changes in phenolics, γ-aminobutyric acid content and antioxidant,antihypertensive and hypoglycaemic properties during ale white sorghum (Sorghum bicolor (L.) Moench) brewing process

Effects of white sorghum brewing process on free amino-acids, γ-aminobutyric acid (GABA), phenolics and bioactivity, including antioxidant (by ABTS⁺ and reducing power, RP, methods), antihypertensive (angiotensin converting enzyme-I, ACE-I inhibition assay), and hypoglycaemic activity (α-glucosidase inhibition assay) were evaluated. From the wort to the beer, free amino acids decreased, but GABA and phenolics increased significantly, positively modifying the bioactive potential. ABTS and α-glucosidase inhibition activity correlated positively with at least one of the phenolic acids evaluated. Ale white sorghum beer presented high content of GABA (7.8 mg L⁻¹), phenolics (40.7 mg total phenolic acids L⁻¹), antioxidant activity (9.14 mmol Trolox equivalent L⁻¹, and 48.8 mmol ascorbic acid equivalent L⁻¹, for ABTS⁺ and RP, respectively), and exhibit ACE-I inhibition (1.0 μg captopril equivalent L⁻¹) and α-glucosidase inhibition (34.5 mg acarbose equivalent L⁻¹) activities. The level of bioactive compounds and its low ethanol content (2.3%), make beer obtained from malted white sorghum a potential functional beverage.     

Exploring the effect of microwave treatment on phenolic flavonoids,antioxidant capacity,and phenolic in vitro bioaccessibility of sorghum

The effect of microwave treatment on phenolics, flavonoids, antioxidant capacity, and phenolic in vitro bioaccessibility of white and red sorghum was evaluated. After microwave treatment for 40 s, the contents of free, bound, and total phenolics in white and red sorghum increased by 15.6–42.6, 4.0–23.4, and 19.7–66.0 mg gallic acid equivalents 100 g⁻¹ dry weight (DW), respectively, and the contents of free, bound, and total flavonoids increased by 9.4–11.2, 4.8–5.4, and 14.2–16.6 mg rutin equivalents 100 g⁻¹ DW, respectively. With increasing microwave treatment time, the contents of phenolic acids and flavonoids in white and red sorghum first increased and then decreased. Additionally, the changes in antioxidant capacity indicated a similar trend with phenolic contents for white and red sorghum. In vitro gastrointestinal digestion indicated that microwave treatment had no effect on the phenolic bioaccessibility of white and red sorghum but increased the release amount of phenolic acid and antioxidant capacity.     

Replacement of buckwheat by black sorghum flour on soba-type noodles

Incorporation of black sorghum flour containing high levels of polyphenols and slowly digestible starch could provide opportunity to enhance nutritional functionality of noodles. Soba-type noodles were prepared based on a typical wheat-buckwheat (65:35) formulation by replacement of buckwheat flour with black sorghum flour at 0%, 25%, 50%, 75% and 100%. Noodle colour, texture, total phenolics, antioxidant capacity, in vitro starch digestibility and sensory acceptability were evaluated. Increasing the addition of black sorghum flour significantly (P < 0.05) decreased the firmness (g) in noodles and imparted a darker colour but increased total polyphenolics and antioxidant capacity. Significantly (P < 0.05) lower rapidly digestible starch and higher resistant starch was found in noodles with >50% replacement with black sorghum flour. Overall acceptability of noodles showed preference for noodles containing 25%–75% black sorghum flour. This study demonstrates the potential of using black sorghum as a novel functional food ingredient in noodle manufacturing.     

Development of weaning food formulations based on malting and roller drying of sorghum and cowpea

Sorghum and cowpea were steeped in water for 16 h, allowed to germinate for 72 and 24 h respectively, then dried to about 14% moisture. Roots and shoots of sorghum sprouts were cleaned off and the devegetated malt was kilned at 70°C, moistened with 3% added water, heaped for about 10 min, milled and sieved to obtain debranned malt flour. Cowpea sprouts were split, dehusked, kilned at 85°C and milled. Malted sorghum and malted cowpea flours were blended in the proportion of 70:30 to prepare the malted weaning food (MWF). A precooked weaning food (RDF) was prepared by roller drying a cold water slurry consisting of 70% pearled sorghum flour and 30% toasted cowpea flour. The cooked paste viscosity of MWF was considerably lower than that of RDF and the blend of raw sorghum (70%) and cowpea (30%), at all comparable slurry concentrations. The protein content of MWF was 13.4% and that of RDF was 13.0%, but the available lysine content of MWF protein was 3.85% and that of RDF protein was 2.95%. The protein efficiency ratio for MWF (2.26) was significantly higher than that for RDF (1.87).     

Impact of moisture and grinding on yield,physical, chemical and thermal properties of wholegrain flour obtained from hydrothermally treated sorghum grains

The present work evaluates the potential of sorghum with high content of tannins for wholegrain flour production. Two types of mills were used: a roller mill (RM) and a blade (BM) mill. The impact of moisture and grinding on yield, physical, chemical and thermal properties were evaluated. Maximum yield was obtained using a BM with 25% moisture in the grain, resulting in 60.9% versus 28% (g flour g⁻¹ of wholegrain sorghum) for the RM. Grain moisture and milling type affected flour colour and ashes. For both mills, the pasting and thermal properties of flour with grain moisture variation were significantly different from the untreated control sample. By studying the procedures for flour production and quality characteristics, it is possible to produce flour with good physical attributes, which can contribute to the development of gluten-free foods based on sorghum for the coeliac population.     

Effect of malt pretreatment on phytate and tannin level of two sorghum (Sorghum bicolor) cultivars

The seeds of two cultivars of Sudanese sorghum (Sorghum bicolor), namely Wad Ahmed and Tabat, were germinated for 4 days to obtain 1‐, 2‐ and 4‐day‐old malts. Sorghum malt (5% and 10%) was added to sorghum flour. The mixtures were incubated at 30 °C with shaking for 30, 60, 90 and 120 min. Malting loss was very slight for both cultivars and for all incubation periods. Phytic acid and tannin contents were assayed for all treatments. The results revealed that phytate and tannin contents were significantly (P ≤ 0.05) reduced when sorghum flour was pretreated with malt. When a mixture containing 10%, 4‐day‐old malt and sorghum flour was incubated for 120 min, it significantly (P ≤ 0.05) reduced phytate and tannin contents by 92% and 98%, respectively, for Wad Ahmed cultivar, while for Tabat they were reduced by 93% and 96%, respectively. The rate of reduction of phytate and tannin content increased with incubation time and malt age and concentration.     

Improving the quality of sorghum injera by decortication and compositing with tef

Injera is an Ethiopian fermented pancake‐like bread made from cereals, with tef being preferred. Decortication and compositing with tef were evaluated as methods to improve the injera‐making quality of red tannin‐free and tannin‐containing sorghums. Both decortication and compositing improved sorghum injera quality. Concerning decortication, mechanical abrasion was found to be more effective than hand pounding because acceptable injera was obtained with lower milling loss. Good quality injera was produced at an extraction rate of 540 g kg^?1 for tannin‐containing and 830 g kg^?1 for tannin‐free sorghum. With compositing, good quality injera was produced with a 50:50 (w/w) composite of whole tannin‐containing sorghum and tef. Both processes reduced the tannin content of the flours, which appeared to relieve the inhibiting effects of tannins on the fermentation. Decortication also seemed to improve sorghum flour injera‐making quality by improving flour pasting as a result of reducing the level of interfering substances such as lipids and proteins. In contrast, the improvement brought about by compositing with tef seemed to be due to inherent differences between tef and sorghum starch granules and an increase in the water solubility index of the flour. Compositing seems to be a more useful method of improving sorghum injera quality than decorticating as it avoids the grain loss associated with decortication. Copyright © 2005 Society of Chemical Industry     

Dextrin,sugar and organic acid profiles of spontaneous and modified gowe: a malted and fermented sorghum beverage from Benin

Gowé is a traditional Beninese fermented red sorghum beverage made from a blend of malted and precooked nonmalted flour. The main objective of this work was to evaluate the degradation of starch during the production of gowé and to characterise the organic acid and sugar profiles of the product obtained using starter cultures. Inoculation was performed with strains of Lactobacillus fermentum or Weissella confusa and of Kluyveromyces marxianus or Pichia anomala used singly or in combination. Size exclusion chromatography revealed that starch was hydrolysed into high molecular weight dextrins (DP over 35), oligosaccharides and glucose, mainly due to the malting and precooking steps. Glucose was the main free sugar, and lactic acid was the main organic acid. The choice of the inoculation strain directly influenced the acidity but also indirectly the sugar content of the resulting gowé and will thus affect consumer acceptability.     

Effects of germination time on phenolics,antioxidant capacity,in vitro phenolic bioaccessibility and starch digestibility in sorghum

The effects of germination time on phenolic, flavonoid, anthocyanin, antioxidant capacities, inhibition capacity of α-amylase, bioaccessibility of phenolic and digestibility of starch in sorghum were evaluated in this study. The levels of total phenolic, flavonoid and anthocyanin in germinated sorghum for 48 h increased by 39.74%, 37.28% and 52.21%, respectively. Germination also increased the composition of phenolic, flavonoid and anthocyanin in sorghum, and their antioxidant capacity and inhibitory rates of α-amylase. Additionally, in vitro digestion results showed that phenolic bioaccessibility increased by 10.18%, and digestibility of starch and expected glycaemic index (eGI) decreased by 13.87% and 5.26 in germinated sorghum for 48 h compared with the ungerminated sorghum. These results indicate that germination might be a green method to improve the nutritional quality of sorghum and promote the development of germinated whole-grain food.     

ACE-inhibitory activity of probiotic yoghurt

In this study, the in vitro angiotensin-converting enzyme (ACE)-inhibitory (ACE-I) activity of peptide fractions from different yoghurt batches was assessed. Inhibition of ACE activity resulted in an overall antihypertensive effect. Yoghurts were prepared either using a sole yoghurt culture including Lactobacillus delbrueckii ssp. bulgaricus Lb1466 and Streptococcus thermophilus St1342, or L. acidophilus L10, L. casei L26 and Bifidobacterium lactis B94 in addition to yoghurt culture. ACE-I activity was determined at weekly intervals during 28 days of cold storage. Peptide fractions showing high ACE-I activity were further purified using multiple-steps of RP-HPLC. All probiotic yoghurts showed appreciable ACE-I activity during initial stages of storage compared with the control yoghurt, with a significant (p<0.05) decrease afterwards. The ACE-I activity ranged from IC₅₀ of 103.30–27.79 μg mL⁻¹ with the greatest ACE inhibition achieved during first and third week of storage. The in vitro ACE-I activity could be related to the peptide liberation via degradation of caseins. In total, 8 ACE-I peptides were characterized originating from α_s2-casein (1), κ-casein (2) and β-casein, of which two well-known ACE-inhibiting peptides, namely Val–Pro–Pro (VPP) and Ile–Pro–Pro (IPP), were identified. These peptides are already used in commercial products.     

Production and characterization of angiotensin converting enzyme (ACE) inhibitory peptides from apricot (Prunus armeniaca L.) kernel protein hydrolysate

Six different proteases (Flavourzyme^®, Neutrase^®, Protamex^®, Alcalase^® 2.4L, Proleather^® FG-F, and papain) were employed to hydrolyze apricot kernel protein (AKP). Alcalase^® is an inexpensive and non-specific protease that has been shown to be useful for the generation of bioactive peptides from AKP. Alcalase^® 2.4L was selected for further study on enzymatic preparation of ACE inhibitory peptide from AKP. After 60-min hydrolysis, the highest ACE inhibition was 82 ± 0.14%. Results of molecular weight distribution revealed that most of ACE inhibition activity was probably attributed to low-molecular weight peptide fraction ranging from 200 to 900 Da. Ultrafiltration on membranes with several molecular weight cutoffs (MWCFs) demonstrated that most of the ACE inhibitory activity was due to peptides with a less than 1,000 Da molecular weight: the IC₅₀ value of the 1-kDa ultrafiltrate was 0.15 ± 0.007 mg mL^?1, while it was 0.378 ± 0.015 mg mL^?1 before ultrafiltration. Additionally, further separation and purification of the ACE inhibitory peptides were carried out using gel filtration and C₁₈ RP-HPLC. The result of research can be used to optimize AKP enzymatic hydrolysis for producing ACE inhibitory peptides which could be used for food industry and nutraceuticals.     

Inhibition of dipeptidyl peptidase IV (DPP-IV) by proline containing casein-derived peptides

Dipeptides with a C terminal Pro inhibit dipeptidyl peptidase IV (DPP-IV), a key enzyme in incretin hormone processing. It was hypothesised that tri- and tetrapeptides with a proline at the C-terminus may also be DPP-IV inhibitors. Therefore, an in silico hydrolysis approach was used to release short (4 ? amino acids) C terminal Pro peptides from the individual caseins which constitute Pro rich substrates. This was achieved using theoretical digestion of caseins with a prolyl oligopeptidase activity. Fifteen peptides were subsequently selected for in vitro DPP-IV inhibitory analysis. Stability of these peptides to gastrointestinal enzymes was also evaluated in silico and the predicted breakdown peptides were assessed for their DPP-IV inhibitory and antioxidant potential. New DPP-IV inhibitors were identified, the most potent being Phe-Leu-Gln-Pro (IC₅₀ 65.3 ± 3.5 μM). A low in vitro antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging) activity was also associated with the peptides studied. The strategy presented highlights the utility of employing an in silico approach for the prediction of food-derived peptides with a potential role in glycaemic management for subsequent development of functional foods.     

Chymotryptic hydrolysates of α-kafirin,the storage protein of sorghum (Sorghum bicolor) exhibited angiotensin converting enzyme inhibitory activity

Kafirin is the main storage protein (prolamin) in sorghum grains. α-Kafirin, the alcohol soluble fraction, was isolated from sorghum flour. Treatment of α-kafirin with chymotrypsin yielded a hydrolysate which on fractionation, using Sephadex G-25 column, yielded four fractions with significant angiotensin converting enzyme (ACE) inhibitory activity in vitro. The IC₅₀ values of these fractions ranged from 1.3 to 24.3 μg/ml. Two of the fractions were found to be competitively inhibiting the enzyme, while two other fractions were non-competitive inhibitors. These results demonstrate that chymotryptic hydrolysates of sorghum prolamin could serve as a good source of peptides with angiotensin I converting enzyme inhibitory activity.     

The choline content of feed ingredients and mixed feeds determined by an enzymatic assay

A recently developed procedure for the determination of choline in ingredients and feeds was utilised to establish the levels and the variability of choline in a series of ingredients and to compare the analysed and calculated choline values of mixed feeds. The concentrations of choline in samples of maize (7), canola meal (3), wheat middlings (1) and dehydrated bakery product (1) were, respectively, 1·55±0·18, 7·59±0·08, 2·35 and 2·39 g kg⁻¹, all higher than ingredient composition table values. Choline contents lower than table values were found in samples of poultry by-products (7) and meat and bone meal (6): 2·18±0·87 and 1·08±0·29 g kg⁻¹, respectively. The average choline concentration found in samples of dehulled soybean meal (7) was 2·73±0·18 g kg⁻¹, similar to table values. The choline in samples of poultry fat (2) averaged 0·48±0·02 g kg⁻¹. Significant correlations between the concentrations of choline and of some components of the proximate analysis were found. The analysed choline concentrations in mixed feeds were only 1·4% lower than the calculated levels based on the ingredient analyses. The procedure was adequate for choline determination in ingredients or mixed feeds. The high variability in the choline content of some ingredients may require analysis for proper feed formulation. © 1998 Society of Chemical Industry.     

Investigation into the potential of commercially available lesser mealworm (A. diaperinus) protein to serve as sources of peptides with DPP-IV inhibitory activity

Food-derived peptides are known to possess inhibitory activity against the dipeptidyl-peptidase IV (DPP-IV) enzyme, a target in the management of type 2 diabetes. While proteins from commonly consumed food commodities have been investigated as precursors of DPP-IV-inhibiting peptides, studies on novel protein sources, such as those from insects, are sparse. This research aimed to determine if DPP-IV inhibitors can be generated upon in vitro digestion or enzymatic hydrolysis of lesser mealworm protein isolate and concentrate. Treatment of the proteins with digestive enzymes and proteases generated hydrolysates with varying potency, thermolysin being the most effective at releasing active peptides (IC₅₀ = 0.63 and 0.60 mg mL⁻¹ for the isolate and concentrate). Ultrafiltration of the thermolysin-treated hydrolysates did not significantly improve the potency. This study shows that DPP-IV inhibitors can be generated from lesser mealworm protein and provides insight on the potential of insects to serve as functional food ingredients.