Effects of particle size on physiochemical and in vitro digestion properties of durum wheat bran

In order to promote the potential health benefits of high fibre products, wheat bran is the main focus of the food industry. The physiochemical and in vitro digestion properties of wheat bran containing different particle size were investigated and compared against raw bran samples. Firstly, the bran sample containing superfine particles (11.63 μm) was hydrolyzed by the α-amylase, pepsin, and pancreatin enzymes separately using a single factor and orthogonal test. Secondly, optimized hydrolysis parameters of superfine particles were employed to measure in vitro digestibility of macronutrients in raw, coarse, medium, and superfine bran particles. The maximum degree of hydrolysis obtained via α-Amylase (concentration 10 mg mL⁻¹, pH 6.6, and time 12.5 min) was 55.71%; pepsin (concentration 50 mg mL⁻¹, pH 1.2, and time 9 h) was 82.10%; and pancreatin (concentration 100 mg mL⁻¹, pH 7.0 and time 12 h) was 84.71%, respectively. The highest in vitro digestibility rate of reducing sugar, protein, fat, and soluble fibre content was observed in superfine bran samples to 33.4%, 82.55%, 91.53%, and 21.66%, respectively.     

Inhibition of the in vitro activities of α-amylase, α-glucosidase and pancreatic lipase by yellow field pea (Pisum sativum L.) protein hydrolysates

The aim of this work was to produce yellow field pea protein-derived peptides as inhibitors of α-amylase, α-glucosidase and pancreatic lipase activities. A pea protein concentrate was hydrolysed with alcalase, chymotrypsin, pepsin or trypsin and the hydrolysates separated into different fractions (<1, 1–3, 3–5, 5–10 kDa) by membrane ultrafiltration. Peptide sequence analysis showed that the alcalase hydrolysate had higher levels of di- and tripeptides when compared with the chymotrypsin, pepsin and trypsin hydrolysates. The peptide fractions inhibited α-amylase and α-glucosidase activities at levels that were similar to the unfractionated hydrolysates. The peptides were more active against α-amylase (inhibition at μg level) than α-glucosidase (mg level). In contrast, the fractionated peptides had reduced ability (IC₅₀ >4.2 mg mL⁻¹) when compared with the unfractionated hydrolysate (IC₅₀ <4.2 mg mL⁻¹) to inhibit lipase activity. Enzyme kinetic studies revealed that the peptides reduced α-amylase activity through competitive inhibition. However, inhibition of α-glucosidase activity was non-competitive.     

Quantification of major camel milk proteins by capillary electrophoresis

Proteins from dromedary camel milk (CM) produced in Europe were separated and quantified by capillary electrophoresis (CE). CE analysis showed that camel milk lacks β-lactoglobulin and consists of high concentration of α-lactalbumin (2.01 ± 0.02 mg mL⁻¹), lactoferrin (1.74 ± 0.06 mg mL⁻¹) and serum albumin (0.46 ± 0.01 mg mL⁻¹). Among caseins, the concentration of β-casein (12.78 ± 0.92 mg mL⁻¹) was found the highest followed by α-casein (2.89 ± 0.29 mg mL⁻¹) while κ-casein represented only minor amount (1.67 ± 0.01 mg mL⁻¹). These results were in agreement with sodium dodecyl sulphate-polyacrylamide gel electrophoresis patterns. Overall, CE offers a quick and reliable method for the determination of major CM proteins, which may be responsible for the many nutritional and health properties of CM.     

Evaluation of various Bacillus coagulans isolates for the production of high purity L-lactic acid using defatted rice bran hydrolysates

Defatted rice bran (DRB) constitutes an abundant by-product stream, generated during rice milling and subsequent bran oil extraction. Enzymatic hydrolysis of starch and protein content in DRB was optimised in terms of solid loading. Among the four solid loadings evaluated (10%, 15%, 20% and 25%), the hydrolysate derived from 20% solids resulted in the highest concentration of glucose (82.3 g L⁻¹) and free amino nitrogen (234.8 mg L⁻¹). The fermentability of the hydrolysate was evaluated via screening of sixteen isolates. All the strains were able to grow and produce high purity L-lactic acid, utilising the DRB as sole carbon and nutrient source. Among the studied strains, the Bacillus coagulans A107 isolate presented the most promising results in terms of final lactic acid concentration (75.9 g L⁻¹), yield (0.90 g g⁻¹) and productivity (2.7 g L⁻¹ h⁻¹). The results of this study indicate that DRB could be employed as an inexpensive, alternative substrate for L-lactic acid production.     

Dietary interference on the oxidation and hydrolysis of liposomes during in vitro digestion

In this study, the influence of dietary compounds, including antioxidants (ethylenediaminetetraacid, ascorbic acid, catechin), chitosan and lactoferrin, on the stability of liposomes during in vitro adult and infant digestion was investigated in terms of formation of thiobarbituric acid-reactive substances (TBARS) and free fatty acid release. Liposomes were more sensitive to degradation in adults than in infants, suggesting lower pH (1.5) and higher concentration of pancreatic enzymes (3.2 mg mL⁻¹) and bile salts (5 mg mL⁻¹) that indicated greater damage to the structure of liposomes. Compared to ethylenediaminetetraacid and ascorbic acid, catechin presented the most apparent protective effect against liposomal oxidation by scavenging free radicals. Chitosan promoted the formation of TBARS, while lactoferrin facilitated the hydrolysis rate of liposomes under both adult and infant conditions. This study provided an insight into the development of healthcare products and functional foods related to liposomes for special populations.     

Angiotensin-converting enzyme inhibitory activity of hydrolysates generated from whey protein fortified with salal fruits (Galtheria shallon) by enzymatic treatment with Pronase from Streptomyces griseus

Whey proteins mixed with salal fruits extract (0–20% w/w) were hydrolysed with Pronase E from Streptomyces griseus for a period of 8 h. The angiotensin-converting enzyme (ACE) inhibitory activity of the hydrolysates was highest (IC₅₀: 0.087 mg mL⁻¹) for samples fortified with the highest extract concentration (20%). Peptides (>7 amino acids) with documented ACE inhibitory activity (DAQSAPLRVY, ALPMHIR, DKVGINY, LHLPLPL, YPFPGPI, YPFPGPIPN, VYPFPGPIPN) were identified bv LC-MS/MS data analysis using a database search approach. Fluorescence spectra of the whey proteins mixed with salal fruits extract indicates fluorescence quenching for α-lactalbumin. SDS-PAGE analysis suggests that α-lactalbumin is less susceptible to proteolysis when the extract is included in the formula. Data indicate that α-lactalbumin may be interacting with phenolic compounds naturally present in salal fruits. These interactions and the formation of complexes between a-Lac and phenolic compounds may affect the hydrolysis pattern of whey protein and the release of peptides with ACE-inhibitory activity.     

Mixed fermentation of jujube juice (Ziziphus jujuba Mill.) with L. rhamnosus GG and L. plantarum-1: effects on the quality and stability

This study was conducted aiming at improving the quality of jujube juice by mixed fermentation of lactobacilli. Selection of favourable lactobacilli and addition of nitrogen sources were explored as an efficient method to improve the viability of probiotic in jujube juice. After fermentation, the viability increased to 9.15 ± 0.10 Log CFU mL⁻¹, while the content of lactic acid increased to 5.61 ± 0.03 mg mL⁻¹. The total phenolic and total flavonoid content were 2663.03 ± 11.95 μg mL⁻¹ and 163.95 ± 0.47 μg mL⁻¹ respectively. Moreover, the stability of fermented jujube juice during refrigeration was investigated, which showed that the viability dropped to 8.84 ± 0.6 Log CFU mL⁻¹ and the concentration of lactic acid slowly increased to 6.51 ± 0.04 mg mL⁻¹; the ABTS value showed a 4.26% reduction and FRAP value did not significantly (P < 0.05) change during refrigerated storage. In addition to the existing knowledge, our data aid to the future applications of the jujube as a potential ingredient in novel probiotic foods formulation.     

Antioxidant function of tea dregs protein hydrolysates in liposome–meat system and its possible action mechanism

Tea dregs possess abundant proteins, and the objective of this study was to investigate the antioxidant activity of tea dregs protein hydrolysate with limited hydrolysis by protamex and its possible action mechanism. Tea dregs protein was hydrolysed by alcalase, protamex or neutrase. The hydrolysis condition was optimised, and the hydrolysate was characterised for 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) radical‐scavenging activity, hydroxyl radical‐scavenging activity and antioxidant activity in linoleic acid (LA) system and in chicken products. Tea dregs protein hydrolysate (TDPH) was formulated (0.1%, 0.5%, 1.0%, w/w) into chicken products to determine in situ antioxidant efficacy. Thiobarbituric acid‐reactive substances (TBARS) and peroxide value (POV) formed in chicken products during storage (4 °C, 0–7 days) were analysed. Results showed that the optimum hydrolysis condition was at 50 °C, pH 7.0 for 20 min, and the concentration of tea dregs protein was 1.5%; ratio of protamex to substrate was 6000 U g^?1. The radical‐scavenging ratio of TDPH to 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) was 90.30% at the concentration of 0.1 mg mL^?1 and that to hydroxyl radical was 65.18% at the concentration of 1.0 mg mL^?1. Moreover, it also showed strong antioxidant activity both in linoleic acid (LA) system and in chicken products. The molecular weight distribution of tea dregs hydrolysates was determined by nanofiltration tubular membrane, and the protein hydrolysates with molecular weight above 8000 Da had more effective antioxidant activity. The radical‐scavenging activities to DPPH and hydroxyl radical were 85.72% at 0.1 mg mL^?1 and 71.52% at 1.0 mg mL^?1, respectively. These findings suggest that the enzymatic hydrolysate of tea dregs protein probably possesses the specific peptides/amino acids which could stabilise or terminate the radicals through donating hydrogen. In addition, the hydrolysate could form a physical barrier around the fat droplets.     

An eco-friendly pressure liquid extraction method to recover anthocyanins from broken black bean hulls

This study aimed to recover the anthocyanin-rich extract from broken black bean hulls by pressurized liquid extraction (PLE) and to study their chemical stability, inhibition capacity toward carbohydrate-enzymes and application in gelatin. A Box-Behnken design (BBD) coupled to response surface methodology (RSM) was applied in order to maximize the anthocyanin extraction conditions. Optimum PLE conditions obtained were ethanol:citric acid solution 0.1 mol L⁻¹ (30:70, v/v), a flow rate of 4 mL min⁻¹_, and 60 °C. Delphinidin-3-glucoside was the main anthocyanin quantified. The PLE crude and purified anthocyanin-rich extracts inhibited α-amylase (IC₅₀: 0.52 and 2.85 mg mL⁻¹) and α-glucosidase (0.03 and 0.15 mg mL⁻¹) enzymes, respectively. The PLE anthocyanin-rich extracts showed higher stability in low temperatures and in the absence of light. Besides, the application in gelatin provided a natural color and supplementation with antioxidant compounds. Overall, anthocyanin-rich extract obtained from black bean by-product using an eco-friendly PLE method shows potential as natural colorant and supplement.Industrial relevancePLE method is an emerging technique that performs fast and efficient extractions under high temperature and pressure conditions. The association of green technologies with green solvents makes PLE an eco-friendly technology. This article provides information about the extraction of anthocyanin-rich extracts from the broken black bean hulls by green PLE process under optimized conditions. The process allowed to obtain antioxidant-rich extracts with high application potential in food, supplements, and pharmaceutical industries.     

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.     

Isolation of bovine serum albumin from whey using affinity chromatography

The adsorption of bovine serum albumin (BSA) to a chromatography resin with immobilised llama antibody fragments as affinity ligands was investigated. The maximum adsorption capacity of the affinity resin was 21.6 mg mL⁻¹ with a Langmuir equilibrium constant of 20.4 mg mg⁻¹. Using packed bed chromatography, BSA was adsorbed from pure BSA solutions. Recovery was achieved by desorption at pH 3. In experiments with initial BSA concentrations of 1 mg mL⁻¹ and 0.1 mg mL⁻¹, BSA could be concentrated to 6.9 and 7.7 mg mL⁻¹, respectively. BSA was also isolated from filtered bovine cheese whey containing less than 0.1 mg mL⁻¹ BSA. The purified BSA was in this case concentrated to 7.4 mg mL⁻¹ BSA. The presence of other components in the feedstock did not alter the adsorption capacity of the affinity resin. The results show that high recovery combined with high purity can be obtained using affinity chromatography.     

Inhibitory effect of Zanthoxylum bungeanum maxim. and Capsicum annuum L. on the activities of pancreatic lipase and α-amylase

Zanthoxylum bungeanum maxim. (ZBM) and Capsicum annuum L. (CAL) are popular condiments in China. In this study, the inhibition of pancreatic lipase and α-amylase by ZBM and CAL extracts, as well as catechin, rutin, hydroxy-α-sanshool (from ZBM extract) and capsaicin (from CAL extract), was determined. The half maximal inhibitory concentration (IC₅₀) values of ZBM extract, CAL extract, rutin, hydroxy-α-sanshool and capsaicin against pancreatic lipase were 82.1, 533.5, 583.8, 565.7 and 62.4 μg mL⁻¹, respectively, while that against α-amylase were 125.6, 1167.2, 213.2195.6 and 163.2 μg mL⁻¹, respectively. Catechin had no detectible inhibition on the two enzymes even at 4 mg mL⁻¹. The combination of hydroxy-α-sanshool and capsaicin against the two enzymes showed similar inhibition trends to that of ZBM and CAL extracts (synergism at low concentrations but antagonism at high concentrations), suggesting the two compounds were closely associated with the functions of the crude extracts. The results obtained from the in vitro digestion were similar but with a lower inhibition rate. Kinetic studies revealed that ZBM extract, hydroxy-α-sanshool and capsaicin showed mixed-type inhibition for pancreatic lipase and α-amylase. Molecular modelling suggested capsaicin had a higher affinity to the two enzymes, with glide scores of −8.18 and −7.87 kcal mol⁻¹, respectively.     

Myosin affects the structure and volatile flavour compounds binding of G-actin in grass carp

The effects of myosin (0, 0.2, 0.4, and 0.6 mg mL⁻¹) on the protein structure and volatiles adsorption capacity of G-actin from grass carp were investigated. The results showed that the myosin addition increased the surface hydrophobicity and sulfhydryl contents of G-actin. The Raman spectroscopy analysis showed that the α-helix and β-sheet of G-actin were converted into β-turn and random coil with 0.2 and 0.4 mg mL⁻¹ of myosin, while only the β-turn content increased with 0.6 mg mL⁻¹ of myosin. The GC-MS analysis indicated that with myosin addition, the adsorption capacities of G-actin on alcohols (1-pantanol, 1-hexanol, 1-octen-3-ol, and 1-octanol) and ketones (2-pentanone, 2-heptanone, 2-octanone, and 2-nonanone) were enhanced; meanwhile, the binding of G-actin to aldehydes (pentanal, hexanal, octanal, and nonanal) was weakened. It was probably due to the formation of actomyosin, and also the excess myosin when treated with high concentrations (0.4 and 0.6 mg mL⁻¹) of myosin.     

Effects of carboxymethylation,hydroxypropylation and dual-enzyme hydrolysis combination with heating on in vitro hypoglycaemic properties of coconut cake dietary fibres

Effects of carboxymethylation, hydroxypropylation and dual-enzyme hydrolysis combined with heating on in vitro hypoglycaemic properties of coconut cake dietary fibre (CCDF) were studied. Results showed that all the three modification methods could effectively improve (P < 0.05) the glucose-adsorption ability (GAA), glucose dialysis retardation index (GDRI), α-glucosidase and α-amylase inhibition activity of CCDF. The highest GAA (4.45–4.93 mm  g⁻¹), GDRI (85.09–86.94% mm  g⁻¹) and α-glucosidase inhibition activity (16.39–19.37%) were found on CCDFs modified by hydroxypropylation and carboxymethylation, attributed to the increased soluble dietary fibre content, viscosity and water retention and swelling capacity. Moreover, CCDF treated by enzymatic hydrolysis combined with heating demonstrated the highest α-amylase inhibition activity (53.95%), attributed to the high specific surface area, more porous surface structure and formation of fibre–amylase complex proved by fluorescence spectroscopy. These results suggest that the modified CCDFs could be used as low-calorie functional ingredients in food or other industries.     

Analytical method to detect adulteration of ground roasted coffee

In this work, an HPLC-based detection method for identification of coffee powder adulterated with roasted barley, wheat and rice powders was developed by using various chemical indices such as monosaccharides (mannose, rhamnose, glucose, galactose, xylose and arabinose), trigonelline and nicotinic acid. As a quality assurance, the recovery efficiencies were 84.1%–90.2% for the monosaccharides, 113.6% for trigonelline and 114.9% for nicotinic acid. The limits of detection were 0.047–0.070 mmol kg⁻¹ for the monosaccharides, 0.209 mg kg⁻¹ for trigonelline and 0.117 mg kg⁻¹ for nicotinic acid. The glucose concentration in coffee samples adulterated with roasted barley, wheat and rice at 99:1 (w/w) mixing ratio was significantly different from the control coffee sample. The limit of discrimination from adulterated coffee samples was 1% (w/w) when glucose was used as a chemical index (P < 0.05).     

Effects of selected processing treatments on antigenicity of banana prawn (Fenneropenaeus merguiensis) tropomyosin

Different processing techniques were assessed to attenuate the antigenicity of banana prawn tropomyosin (Fenneropenaeus merguiensis). Frying and boiling at different temperatures, acid treatment using different acids and storage at −20 °C up to 3 months were investigated. Untreated prawn sample was used as a control. Frying significantly increased antigenicity (6–8 times) in temperature-dependent manner, whereas the trend was fundamentally reversed with boiling. Boiling at 121 °C resulted in the lowest antigenicity (12.99 mg mL⁻¹) among all heat-treated samples, yet higher than the control (5.06 mg mL⁻¹). Freezing had initially very minor impact, although prolonged storage at −20 °C increased antigenicity slightly (2.29 mg mL⁻¹) compared with control. Antigenicity was impacted the most by a reduction in pH independent on the type of acid as both acetic and HCl acids significantly reduced antigenicity of tropomyosin by ~90% compared with control. This could be considered as a new approach to processing that may potentially reduce tropomyosin-derived antigenicity in prawns and prawn products. This study also confirmed the actual molecular weight of banana prawn tropomyosin was 37 kDa implementing a new methodology using unstained gel.     

Antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris vegetative cells in apple juice

The aim of this study was to investigate the antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris. Minimum inhibitory concentrations of cinnamic acid and chlorogenic acid were 0.375 and 2.0 mg mL⁻¹, and the minimum bactericidal concentrations were 0.50 and 4.0 mg mL⁻¹, respectively. The apple juice ingredients had little influence on the inactivation of A. acidoterrestris. After treatment with cinnamic acid and chlorogenic acid, the morphology of A. acidoterrestris cells were severely destroyed; the leakage of nucleic acids and proteins increased significantly. SDS-PAGE investigation of bacterial proteins proved that the loss of soluble proteins was obvious as well. These results demonstrated that cinnamic acid and chlorogenic acid exerted their antibacterial activity mainly by an action mode of membrane disruption. This study provides an alternative method for the control of A. acidoterrestris-related spoilage in the fruit juice/beverage industry.     

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.     

In vitro evaluation of digestive enzyme inhibition and antioxidant effects of naked oat phenolic acid compound (OPC)

This research was focused on digestive enzyme inhibition and antioxidant properties of naked oat phenolic acid compound (OPC). Free and bound phenolic acid were separated from ethyl acetate fraction, n-butanol fraction and aqueous fraction. The interactions between OPC and main digestive enzymes (α-amylase, α-glucosidase, pepsin and trypsin) were studied. It was shown that the semi-purified bound phenolic acid (semi-purified by AB-8 column) has a competitive alpha-glucosidase inhibitor, while OPC of the organic extract fraction exhibited the characteristics of a mixed inhibitor. Bound phenolic-n-butanol fraction (IC₅₀ = 98.39 ± 0.89 µg mL⁻¹) had the strongest ability to scavenge the 1,1-diphenyl-2-picrylhydrazyl (DPPH). Additionally, the starch hydrolysis degree of n-butanol extraction naked oat phenolic compound was significantly lower than other fractions in vitro. The integrated results suggested that OPC could be considered as potential healthy factor to control postprandial blood glucose, and the mechanism maybe via anti-digestion, antioxidation and interaction with diabetes-related starch.     

Effect of fermentation by Bacillus subtilis on antioxidant and cytotoxic activities of black rice bran

Black rice bran was fermented with Bacillus subtilis KU3 isolated from Korean traditional food, Kimchi. Antioxidant and cytotoxic activities of the fermented black rice bran were investigated. Total phenolic and anthocyanin contents decreased from 171.54 mg GAE g^?1 and 2.31 mg g^?1 to 139.13 mg GAE g^?1 and 2.12 mg g^?1, respectively, after fermentation. Antioxidant activities determined by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, β‐carotene bleaching and ferric thiocyanate assay were correlated with total phenolic and anthocyanin contents. Non‐fermented black rice bran extract (NFBE) showed greater antioxidant activities than fermented black rice bran extract (FBE). Cytotoxic activities measured by MTT assay showed that both NFBE and FBE had over 50% activities. The cytotoxic activities of FBE against MCF‐7 and HeLa cells were 71.65% and 68.07%, respectively, at 8.0 mg mL^?1, but those of NFBE were lower than 50%. These results suggested that the cytotoxic activity of black rice bran improved through fermentation, while antioxidant activity reduced.