Assessment of the bioavailability of toxic and non-toxic arsenic species in seafood samples

Bioavailability of total arsenic, toxic (arsenite, As(III); and arsenate, As(V)), and non-toxic (monomethylarsonic acid, MA; dimethylarsonic acid, DMA; arsenobetaine, AB; and arsenocholine, AC) arsenic species has been assessed in different raw seafood samples (white fish, cold water fish and molluscs) by using an in vitro model that combines simulated gastric and intestinal digestion/dialysis methods. Correlations between arsenic species bioavailability and seafood nutrient contents (fat and protein) have also been established. Total arsenic content in seafood samples, and dialyzable and non-dialyzable fractions, were analyzed by inductively coupled plasma – mass spectrometry (ICP–MS) after a microwave-assisted acid digestion treatment. The determination of the different arsenic species concentrations in the samples (after an optimised matrix solid phase dispersion (MSPD) approach) and in the dialyzable fraction was done by high performance liquid chromatography (HPLC) coupled to ICP-MS as a selective detector. Accuracy of the procedure (total arsenic determination) was assessed by analyzing DORM-2 and BCR-627 certified reference materials. The accuracy of the in vitro procedure was established through a mass-balance study. After statistical evaluation (95% confidence interval), good accuracy of the whole in vitro process, for total arsenic and for arsenic speciation, was observed. High dialyzability percentages for total arsenic and for arsenic species were found (i.e. from 84.6 ± 1.7% to 106 ± 2.6%). Bioavailability of arsenic exhibits a negative correlation with the fat content of the seafood. However, no correlation was observed between the bioavailable fraction of total arsenic and arsenic species and the protein content of the seafood studied.     

Chemical,Functional and Pasting Properties of Defatted Starches from Cowpea and Soybean and Application in Stiff Porridge Preparation

The effects of defatting on the chemical, functional and pasting properties of starches from cowpea and soybean and their application in stiff porridge preparation were studied. Conventional cassava starch served as standard. Defatting of cowpea and soybean resulted in higher yield. Defatted starches also had higher amylose contents with low protein, fat and ash contents than full fat starches. In addition, defatted starches from cowpea and soybean had higher water absorption capacity, swelling power, blue value index and low bulk density, higher peak viscosity, trough, final viscosity, setback values than full fat cowpea and soybean starches while cassava starch had higher peak time and pasting temperature than the legume starches. The full fat starches from soybean and cowpea had high breakdown and low setback values than the defatted samples and control. The extensibility values of defatted starches were significantly (p ≤ 0.05) higher than full fat starches but lower than control. There was no significant (p ≥ 0.05) difference in texture and appearance of stiff porridges prepared from cowpea, soybean and cassava starches. Similarly, there was no significant (p ≥ 0.05) difference in mouldability, stickiness and overall acceptability between defatted starches and control but significantly different (p ≤ 0.05) with the full fat starches. It is therefore concluded that consumption of such stiff porridges could be beneficial to individuals requiring decreased and/or slow starch digestibility such as diabetic patients and long distance athletes since legume starches are known to have low starch digestibility.     

An investigation of four commercial galactomannans on their emulsion and rheological properties

Four types of galactomannans, namely fenugreek gum (FG), guar gum (GG), tara gum (TG) and locust bean gum (LBG), were investigated in the present study on their emulsion and rheological properties. The M/G ratios of the four galactomannans were 1.2, 1.7, 3.0 and 3.7, respectively. The results revealed that the M/G ratio, along with molecular weight and intrinsic viscosity, played an essential role on emulsion and rheological properties. Surface activity followed the trend: FG > GG > LBG > TG. Emulsion capacity and stability followed the trend: GG > FG > TG > LBG. Storage modulus (G′) followed the same order as intrinsic viscosity, which was: GG > FG > TG > LBG. By fitting the shear-thinning region of the flow curves into the Power law model, power law index (n) increased with increased concentration. Zero shear viscosity (η_sp)₀ was derived by fitting the Newtonian regions of the flow curves into Cross model, and followed the same order with viscosity based molecular weight (M_v), which is: FG > GG > TG > LBG. Exponents of the four gums were generated from Master curves (log (η_sp)₀ versus log C), which were 4.57, 3.92, 4.31 and 4.19 for FG, GG, TG and LBG, respectively.     

Acid and moisture uptake in steamed and boiled sweet potatoes and associated structural changes during in vitro gastric digestion

Orange-fleshed sweet potatoes are a good source of phytochemicals. For these nutrients to be absorbed, they must be released from the food matrix as a result of physical and chemical breakdown. A key factor in food breakdown is gastric acid diffusion into the matrix, and its influence on structural changes. Cooking treatment may influence mass transport properties and structural changes of foods during digestion. The objective of this study was to determine the acid and moisture uptake into sweet potatoes and its influence on macro- and micro-structures during in vitro gastric digestion as a result of varying cooking treatments. Sweet potatoes were cut into cubes and cooked (boiled or steamed) for different times. In vitro oral and gastric digestions were simulated in a shaking water bath at 37 °C. Acidity, moisture content, and solid loss were measured after 9 digestion times (15 to 240 min). Hardness of individual cubes and microstructure (light microscopy) were completed before and after digestion. Effective diffusivity of acid and moisture into the cubes was estimated using MATLAB. Cooking method, cooking severity, and digestion time significantly influenced moisture uptake (p < 0.0001). Acid uptake was significantly influenced by digestion time (p < 0.0001). The change of softening after digestion was influenced by cooking method and severity (p < 0.05). Effective diffusivity of acid ranged from 0.03 × 10^− 10 (mild steamed) to 11.40 × 10^− 10 m²/s (severely boiled). Percent texture decrease after digestion from the initial hardness ranged from 16% (severely steamed) to 34% (mild boiled). Textural changes were related to cell wall breakdown and starch degradation. In general, mass transport properties and macro- and microstructural changes were influenced by cooking treatment and gastric digestion. The link between food cooking and behavior during digestion is crucial in determining optimal food processing and cooking methods for specific food functional properties.     

Milk enhances intestinal absorption of green tea catechins in in vitro digestion/Caco-2 cells model

The effect of milk on the absorption of polyphenols is still controversial so far. In order to determine the impact of milk addition on green tea catechins bioaccessibility and intestinal absorption an in vitro digestion/Caco-2 cell model was applied. Green tea extract (GTE) was solubilized in distilled water at 23 °C and 100 °C, combined with skimmed milk (GTE + 10% milk and GTE + 25% milk) and subjected to simulated gastric and intestinal digestion, followed by transepithelial absorption in Caco-2 cells monolayers. In the mixture with milk, gallated catechins: ECG and EGCG showed binding to milk proteins while EC and EGC seemed to have weaker affinity. Catechins were stable during gastric incubation and very sensitive to intestinal digestion. Bioaccessibility of green tea catechins brewed at 100 °C was higher than brewed at 23 °C. Catechins from digested GTE with 10% and 25% milk exhibited enhanced intestinal permeability in Caco-2 model in comparison to non-digested GTE and digested GTE without milk. Apparent permeability coefficients (P_app) of EGCG and ECG in digested GTE with 25% milk were significantly higher compared to those in GTE with 10% milk, and amounted to 2.41 × 10^− 6 cm/s and 1.39 × 10^− 6 cm/s. The recoveries of all catechins in GTE with milk in Caco-2 cells after 2 h incubation were significantly higher than that without milk. To summarize, these data suggest that milk addition may increase catechin bioavailability by enhancing their transepithelial absorption and uptake from green tea extract.     

Holder pasteurization impacts the proteolysis,lipolysis and disintegration of human milk under in vitro dynamic term newborn digestion

When the mother's own human milk is unavailable or limited, pasteurized human milk from milk banks is preferentially administered instead of infant formula, especially for vulnerable hospitalized neonates. Holder pasteurization (62.5 °C, 30 min) may alter human milk composition and structure, which may modulate its digestive behavior. An in vitro dynamic system was set up to simulate the gastrointestinal digestion of term newborns in order to compare the kinetics of lipolysis, proteolysis and structural disintegration of raw versus pasteurized human milk. Human milk from 5 donors was pooled. Half of the pool was either administrated raw (RHM) or pasteurized (PHM). Digestions were conducted at least in duplicate for RHM and PHM. Heat-induced protein aggregation was observed in PHM. During gastric digestion, β-casein was proteolyzed significantly faster for PHM than for RHM (p < 0.05), whereas lactoferrin tended to be proteolyzed slower (p = 0.07) for PHM. Pasteurization selectively affected the intestinal release of some amino acids. At any time of the gastrointestinal digestion, the lipolysis of PHM was significantly lower than that of RHM, but no impact was observed on the profile of released fatty acids. RHM presented a structural destabilization after 60 min of gastric digestion, while there was no large variation for PHM. In the intestinal phase, the evolution of the particle sizes was rather similar. Overall, Holder pasteurization impacted the proteolysis, lipolysis and disintegration of human milk. However, this impact was limited and the physiologic and metabolic consequences remain to be investigated.     

Studies on the Potential of Malted Digitaria exilis,Cyperus esculentus and Colocasia esculenta Flour Blends as Weaning Food Formulation

This work was aimed at evaluating the functional properties of six varying percentage blends of locally abundant, under-utilized crops; malted acha (Digitaria exilis), aya (Cyperus esculentus) and ede (Colocasia esculenta) as a substitute for the traditional weaning food. The results of bulk density and starch digestibility showed a decrease with increasing percentage addition of malted acha with values from 5.889 ± 0.98 to 7.953 ± 0.103 and − 5.45 to − 13.6 respectively. While water absorption capacity, measure of dispersibility, wettability, swelling power, % solubility increased with increase in percentage addition of malted acha with values from 6.6 ± 0.712 to 8.1 ± 0.1, 2.12 to 37.225, 3.21 ± 0.04 to 3.6 ± 0.03 and 20.64 to 24.46 respectively. There was no significant difference between any of the formulae and the control. Results of pasting properties showed that the peak viscosity, break down, final viscosity and setback values ranges from − 0.42 ± 0.085 to − 3.67 ± 0.085, 5.63 ± 0.045 to 1.79 ± 0.04, − 3.88 ± 0.045 to − 1.475 ± 0.275 and 2.17 ± 0.045 to 2.93 ± 0.045 respectively. The formulae compared favourably with the control, a commercially sold weaning food.     

Gastrointestinal conditions influence the solution behaviour of cereal β-glucans in vitro

The solution behaviour of β-glucans in a gastrointestinal model was investigated in order to explore the mechanisms explaining the physiological effects of the soluble fibre. Asymmetrical flow field-flow fractionation was used to determine the molar mass distribution, and in-line calcofluor labelling allowed specific detection of β-glucans in complex samples. When dispersed in water, weight-average molar mass (M_w) was determined to 1 × 10⁶ g/mol for pure oat and barley β-glucans, and 200 × 10⁶ g/mol for β-glucans in oat bran, indicating that the β-glucans were aggregating. Samples from the gastric digestion displayed disrupted aggregates, while samples from the small intestinal digestion contained re-formed aggregates. Additionally, the aggregates from pure β-glucans were considerably denser after intestinal digestion. This may be construed as gel-formation in the small intestine, which should be tested for its relevance to health effects. Our results signal the difficulties in predicting β-glucan activity in the gastrointestinal tract purely from analysis of the fibre-rich product.     

Structural,thermal and viscoelastic characteristics of starches separated from normal,sugary and waxy maize

Starches separated from five types of maize (two normal, one sugary and two waxy) were investigated for physicochemical, thermal, amylopectin structure and viscoelastic properties. Kisan and Paras were normal maize while Parbhat and LM-6 were waxy maize type. Apparent amylose content of normal and sugary maize was 29.5–32.6 and 41.0%, respectively. Swelling power of normal, sugary and waxy maize starches was 11.6–15.2, 7.8 and 30.2–39.2 (g/g), respectively. X-ray diffraction of maize starches indicated typical A-pattern. Maize starch showed a single broad peak at 2θ=23.2° and a dual peak 2θ=17°–18.1, respectively. Waxy maize starches showed the presence of greater crystallinity than other starches while sugary maize starch showed the presence of lower crystallinity and a large amount of amylose–lipid complex. Intrinsic viscosity [η] of starches in 90% DMSO at 25 °C was 79.7–119.5 ml g⁻¹ for normal, 70.5 ml g⁻¹ for sugary and 107.2–118.1 ml g⁻¹ for waxy starches. Branch chain–length distribution of amylopectin revealed that the apparent amylose, long side chain- and short side chain-amylopectin proportion ranged between 0.0–41%, 13.4–31.5% and 41.5–66.8%, respectively, among the various maize starches. Maize sugary showed the highest apparent amylose content and the least amount of short- and long-side chains of amylopectin. LM-6 and Parbhat showed higher proportion of both long- and short-chain amylopectin as compared to other starches. Distribution of α-1, 4-chains of amylopectin (short-/long-chain) ranged between 2.1 and 3.4, the least for LM-6 and the highest for Paras starch. The transition temperatures (T_o–T_c) ranged between 60.5 and 76.1 °C for sugary, 63.5–76.3 °C for normal and 64.4–81.3 °C for waxy maize starch. The enthalpy of gelatinization (ΔH_gel) of sugary, normal and waxy maize starches was 2.47, 3.7–4.75 and 4.15–5.4 J/g, respectively. Normal and sugary maize starches showed higher G′ and G″ than waxy type starches. The change in the moduli during cooling and reheating of pastes cooked at different temperatures revealed low disintegration of granular structure in starch with higher amylose and amylose–lipid complex as well as low crystallinity. The changes in moduli during 10 h at 10 °C revealed highest retrogradation in maize sugary followed by Paras and Kisan starch.     

Reduced calorie emulsion-based foods: Protein microparticles and dietary fiber as fat replacers

The potential of using microparticulated whey protein (MWP) in combination with either modified starch or locust bean gum (LBG) as fat mimetics to fabricate reduced calorie emulsion-based sauces and dressings was studied. The influence of food matrix composition (protein, polysaccharide, and fat content), ionic strength, and pH on the properties of thermally processed model emulsions (90 °C/10 min) was investigated. Increasing protein concentration (2.5–7.5%) increased the mean (d_3,2) particle diameter due to the formation of large protein aggregates. All MWP-containing systems had a creamy white appearance with high lightness (L* > 75). Addition of fat droplets (5%) further increased their lightness (L* > 90) due to enhanced light scattering. Addition of starch, LBG, or MWP increased emulsion viscosity due to the increased effective volume fraction of the dispersed phase. Addition of calcium chloride (10 mM) and pH adjustment (2–8) caused little change in the physicochemical properties of the mixed systems. Overall, the appearance and rheological properties of the mixed systems were similar to commercial sauces and dressings. This study demonstrates that reduced calorie food emulsions with appearance and consistency similar to those of full-fat versions can be formulated using protein microparticles and polysaccharides.     

Ethanol concentration of fermented broth by ohmic-assisted hydrodistillation

Ohmic-assisted hydrodistillation (OAHD) as an innovative extraction method was employed to concentrate ethanol from corn beer. OAHD reduces the time and energy required for distillation of bioethanol production compared to traditional method. OAHD process was compared to traditional hydrodistillation (HD) for 3 l of 13% (v/v) beer at a constant wattage of 168 W. Test results indicate that the required energy for separation of ethanol in OAHD is 77% less than HD. Moreover, OAHD completed the distillation process in 70.6 ± 1.8 min while HD required 116.1 ± 7.8 min. The concentrations of ethanol in the final distilled product from both methods were similar (56.5% ± 1.3 for OAHD vs. 52.3% ± 4.0 for HD). Interestingly, the process control in OAHD is faster and distillation can be stopped quickly, and consequently, it will contain less unwanted distillate in comparison with HD. The findings of this study introduce OAHD as a potentially economical and environmentally friendly method for bioethanol distillation process.Industrial relevanceIn this research, ohmic-assisted hydrodistillation (OAHD) was used as an advanced hydrodistillation (HD) technique and compared with traditional HD in concentration of ethanol from industrial fermented corn beer. OAHD method was quicker, more economical, more sustainable and with a better ability of process control than HD method. Such advantages can make OAHD as an alternative technique for the production of larger quantities and higher concentrations of ethanol by scaling up the equipments and process in biofuel factories, instead of the conventional HD process.     

Selenium-enriched fermented milk: A suitable dairy product to improve selenium intake in humans

The suitability of Se-enriched fermented milk as a food product for humans has been studied and sensory features, survival of microorganisms in the presence of selenium and Se bioaccessibility are presented. Sensory features and the number of colonies of microorganisms observed until the 4th week after fermentation were not affected at Se concentration levels below 2 μg g^?1. To investigate bioaccessible selenium-containing compounds in selenized fermented milk, total Se was quantified after in vitro gastrointestinal digestion. Results showed that 76 ± 3% Se was extracted after gastrointestinal digestion and 24 ± 6% remained in the insoluble residue. To identify the main species of bioaccessible Se of low molecular weight (MW) generated during gastrointestinal digestion, liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) was used. Results showed that identified selenocompounds were smaller than 1.5 kDa, with selenocystine and Se-methylselenocysteine being the most abundant compounds present in the extracts.     

Digestion property and synergistic effect on biological activity of purple rice (Oryza sativa L.) anthocyanins subjected to a simulated gastrointestinal digestion in vitro

Anthocyanins, a group of polyphenolic pigments, have been proved to possess various bioactivities. However, they are unstable in the small intestine and absorbed with low bioavailability. The discrepancy between the low bioavailability of anthocyanins and their good bioactivities has not been illuminated yet. Moreover, information about the digested property and stability of purple rice anthocyanins in the alimentary tract is still limited. Thus, the present work was designed to study the digestion property and the changes in antioxidant and cytoprotective activities of purple rice anthocyanins using an in vitro digestion model, and to investigate the interactions between gastric and intestinal digested anthocyanins. The results showed that anthocyanins amount and antioxidant and cytoprotective effects didn't change significantly during gastric digestion. However, about 76% of total anthocyanins were degraded during intestinal digestion. The IC₅₀ values of intestinal digested sample tested by DPPH and ABTS methods were about 19.1 and 16.9 μg/mL, respectively, far higher than that of non-digested sample (about 7.7 and 7.1 μg/mL, respectively). Cytoprotective effect of intestinal digested sample also decreased significantly. Synergistic effects on antioxidant and cytoprotective activities were observed between the gastric and intestinal digested samples at a relative low concentration. Those results suggest that the bioactivities of purple rice anthocyanins may be changed after digestion and enhanced through the synergies between their gastric and intestinal digested catabolites.     

Release of multifunctional peptides by gastrointestinal digestion of sea cucumber (Isostichopus badionotus)

Sea cucumber is a benthic marine organism distributed worldwide and used as food in several Asian countries. The species Isostichopus badionotus is captured intensively off the Yucatan Peninsula, Mexico. Boiled I. badionotus was subjected to in vitro simulated gastrointestinal digestion using pepsin and a pepsin–Corolase PP^® mixture. ACE-inhibitory and radical scavenging activities, iron reducing capacity and cytotoxic effects against colorectal cancer cells were evaluated in the hydrolysates and their ultrafiltered fractions. ACE-inhibitory activity was potent in fractions containing peptides <3000 Da, an effect augmented with combined action of gastric (pepsin) and intestinal (Corolase PP^®) enzymes (IC₅₀ = 0.038 ± 0.004 mg/mL). Antioxidant activity was exerted by peptides with low and high molecular weights, depending on hydrolysis method. This is the first report of cytotoxic capacity against colorectal HT-29 cells in peptides from sea cucumber. Sea cucumber hydrolysates and ultrafiltered fractions are potential ingredients for development of functional foods.     

In vitro digestion of foods using pH-stat and the INFOGEST protocol: Impact of matrix structure on digestion kinetics of macronutrients,proteins and lipids

It is currently admitted that food structure can facilitate or delay the release of nutrients during digestion and their absorption by the human body. The aim of this study is to propose an in vitro method able to assess the behavior of lipo-proteinic matrices with different structures during digestion. Two model matrices of exactly the same compositions (10% oil, 15% whey proteins, w/w) were designed: i) A liquid emulsion (LE) made of small fat droplets (1 μm) dispersed in a liquid continuous phase containing native whey proteins, ii) a solid emulsion (SE) made of a continuous whey protein gel entrapping large oil droplets (20 μm). The two matrices were digested through an in vitro gastro-intestinal protocol based on the INFOGEST guidelines using pH-stat to monitor the enzymatic hydrolyses of both proteins and lipids. By further digesting lipid-free matrices in the same conditions, the contributions of the proteolytic and lipolytic reactions were evaluated. Significant differences were observed between matrices at both short and long digestion times. The initial rates of both proteolysis and lipolysis were slower for SE than LE because of the gel state of the continuous phase. At the end of the experiments, SE led to a smaller extent of lipolysis (DH_{lip_SE} = 51% < DH_{lip_LE} = 81%) but a greater extent of proteolysis (DH_{prot_SE} = 80% > DH_{prot_LE} = 52%) because of the higher sensitivity to digestion of denatured whey proteins. These results highlight the impact of matrix structure on enzyme accessibility, and show that the proposed method is suitable to monitor the digestion of complex food matrices.     

Moderation of oxonate-induced hyperuricemia in rats via the ingestion of an ethanol-soluble fraction of a shark cartilage proteolytic digest

A shark cartilage proteolytic digest was fractionated by selective extraction with 75% ethanol. Peptides in the digest were recovered in the 75% ethanol-soluble fraction. The ethanol-soluble fraction showed lower viscosity and higher solubility in water than the crude digest. Oxonate-induced hyperuricemia in rat was suppressed by the oral administration of the ethanol-soluble fraction of the digest (1 g/kg body weight/day) for 28 days. Single administration of the ethanol-soluble fraction also reduced blood uric acid level in a dose-dependent manner. Administration of the ethanol-soluble fraction of the digest (1 g/kg body weight/day) significantly increased serum inhibitory activity against xanthine oxidase, whereas the ethanol-soluble fraction had no in vitro xanthine oxidase inhibitory activity. These facts suggest that peptides in the ethanol-soluble fraction might be converted into smaller peptides with xanthine oxidase inhibitory activity during digestion, absorption, and metabolism.     

Fluidized bed microencapsulation of Lactobacillus reuteri with sweet whey and shellac for improved acid resistance and in-vitro gastro-intestinal survival

This study aimed at developing a micro-encapsulation process for Lactobacillus reuteri DSM 20016 with sweet whey powder and dietary shellac by a two-step fluidized bed granulation and top spray coating technique to enhance resistance to acid conditions and to increase bacterial survival under gastro-intestinal conditions. L. reuteri DSM 20016 was a top-spray fluid bed granulated at 50 °C with sweet whey and different thermo-protectants followed by top spray coating with an aqueous shellac solution. Moisture content and particle size of granules measured by infrared moisture balance and laser diffraction were appropriate for the encapsulation of the bacteria. Bacterial survival rates were evaluated by pour plate counting. Viabilities after granulation were 43 ± 4.5%, after 15 min shellac coating 22.69 ± 2.41% and 14.86 ± 1.29% after 30 min coating time. Endpoint bacterial count after 28 d storage at 4 °C remained equal for coated and uncoated bacteria. After incubation in gastric acid and intestinal conditions the final survival rate of coated L. reuteri DSM 20016 with 76.74 ± 24.36% was higher compared to free cells with 17.74 ± 10.51% (p = 0.0388).To conclude fluidized bed technology with a combination of sweet whey and shellac as encapsulation material offers distinct acid resistance for L. reuteri DSM 20016 and enables improved survival during gastro-intestinal transit. Hence the usage of shellac and sweet whey powder as encapsulation material improves the effectiveness of probiotic food applications.     

Composition,morphology, molecular structure,and physicochemical properties of starches from newly released chickpea (Cicer arietinum L.) cultivars grown in Canada

Starch from four cultivars (CDC Xena, CDC Flip 97-133C, CDC 418-59, CDC ICC 12512-9) of chickpea (cicer arietinum L.) grown in Saskatchewan, Canada was isolated and variability in composition, morphology, molecular structure and physicochemical properties was evaluated. The yield of starch was in the range 32.0–36.8% on a whole seed basis. The starch granules were oval to spherical with smooth surfaces. The granule size distribution ranged from 5 to 35 μm. The free lipid, bound lipid, total amylose and the amount of amylose complexed with native starch lipids ranged from 0.04% to 0.08%, 0.21% to 0.46%, 33.9% to 40.2% and 9.1% to 15.9%, respectively. There was no significant difference in branch chain length distribution of amylopectin among the starches. The X-ray pattern was of the C-type. The relative crystallinity was in the range 31.3–34.4%. Swelling factor and amylose leaching in the temperature range 50–90 °C ranged from 1.6% to 25.9% and 8.61% to 36.1%, respectively. All four starches exhibited nearly identical gelatinization temperatures. However, the enthalpy of gelatinization was in the range 11.2–13.1 J/g, respectively. The starches differed significantly with respect to peak viscosity (3223–4174 cp), breakdown viscosity (394–1308 cp) and set-back (3110–4281 cp). Starches were hydrolyzed by acid to nearly the same extent. The amount of rapidly digestible, slowly digestible and resistant starch contents ranged from 10.9% to 15.7%, 48.5% to 60.2% and 24.1% to 40.6%, respectively.     

Rheological characterization of experimental dairy creams formulated with locust bean gum (LBG) and λ-carrageenan combinations

The influence of the locust bean gum (LBG)–λ-carrageenan stabilizer combination on the rheology of dairy creams was analyzed. A central composite factorial design was used to choose the LBG–λ-carrageenan ratio, the weight fraction of each gum ranging from 0 to 0.1 g per 100 g cream. Cross’ rheological model was closely fitted to describe the flow curves of the samples and Cross parameters were correlated with gum concentrations. The rheological behaviour of model aqueous gum solutions, with the same pH, ionic strength, and competitive solute concentration as the cream serum, was also examined to analyze gum interactions. Strong interaction of λ-carrageenan with cream components, probably with caseins, may be anticipated based on a great increase in viscosity. The functional role of LBG seems to be associated with an increase in the emulsion shear stability.     

Functional properties and Angiotensin-I converting enzyme inhibitory activity of soy–whey proteins and fractions

Soy proteins when prepared to high purity can confer good functional properties and the whey by-product is a potential source for bioactivity. In this study, we determined the protein, moisture, fiber, solubility, foaming, emulsion properties, as well as Angiotensin-I converting enzyme (ACE-I) inhibitory activity of prepared soy–whey proteins and its fractions. The soy–whey proteins were fractionated into < 5, > 5, > 10, and > 50 kDa using ultrafiltration. The expanded AACC methods were used to determine protein, moisture, and fiber analyses of the whey and its fractions. Solubility method was conducted to determine the protein solubility profile of the soy–whey and its fractions at varying pHs. Turbidimetric method was used to evaluate emulsifying activity (EA) and emulsion stability (ES). There were significant differences observed in moisture, protein and salt contents between unfractionated, > 50 kDa and smaller sized fractions. No significant differences were observed with phytic acid and total dietary fiber contents among all samples. The unfractionated whey protein and > 50 kDa fraction showed better solubility than other fractions. Unfractionated whey protein had the highest foam capacity (42.7 mL) while the fraction > 5 kDa showed the greatest foaming stability (46 min). The highest emulsion activity (0.33 ± 0.1) and stability (825.1 ± 45.1) was obtained with the > 50 kDa fraction while the unfractionated whey protein had the highest ACE-I inhibition activity. The findings indicate that soy–whey protein fraction (> 50 kDa) had good solubility, emulsion activity and stability, while the unfractionated whey protein exhibited the strongest ACE-I inhibition percentage (19%).