The effect of in vitro gastrointestinal simulation on bioactivities of kefir

Kefir is a fermented milk beverage and known to have positive effects on gut microbial diversity and human health. In this study, digested and undigested kefir samples were compared for changes in their antihypertensive, antidiabetic, antioxidant and antimicrobial activities. Results showed that the amount of total phenolic substances, 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH) activity, and the angiotensin-converting enzyme inhibitor (ACE-I) activity increased from 43.76 ± 0.005 mg gallic acid equivalents (GAE)/L, 4.20 ± 0.55%, and 9.91 ± 3.90% in undigested kefir to 668.16 ± 3.332 mg GAE/L, 63.06 ± 0.64%, and 98.88 ± 0.42% in digested kefir, respectively. While the dipeptidyl peptidase IV-inhibitory (DPPIV-I) activity of undigested kefir increased by 19.11 ± 7.35% after digestion, the optical density of the ferric-reducing antioxidant power (FRAP) decreased from 1.188 ± 0.05 to 0.278 ± 0.009, and the protein amount decreased from 101.4 mg L⁻¹ to 12.42 mg L⁻¹ in digested kefir. No antimicrobial effect was observed in undigested kefir, whereas, digested kefir samples were active, but only against Escherichia coli. These results show that the gastrointestinal digestion processes of kefir generally increase the number of bioactive molecules, and the digestion process must be taken into account to determine the biological capability of foods.     

Chemical composition and sensory analysis of cheese whey‐based beverages using kefir grains as starter culture

The aim of the present work was to evaluate the use of the kefir grains as a starter culture for tradicional milk kefir beverage and for cheese whey‐based beverages production. Fermentation was performed by inoculating kefir grains in milk (ML), cheese whey (CW) and deproteinised cheese whey (DCW). Erlenmeyers containing kefir grains and different substrates were statically incubated for 72 h at 25 °C. Lactose, ethanol, lactic acid, acetic acid, acetaldehyde, ethyl acetate, isoamyl alcohol, isobutanol, 1‐propanol, isopentyl alcohol and 1‐hexanol were identified and quantified by high‐performance liquid chromatography and GC‐FID. The results showed that kefir grains were able to utilise lactose in 60 h from ML and 72 h from CW and DCW and produce similar amounts of ethanol (～12 g L^?1), lactic acid (～6 g L^?1) and acetic acid (～1.5 g L^?1) to those obtained during milk fermentation. Based on the chemical characteristics and acceptance in the sensory analysis, the kefir grains showed potential to be used for developing cheese whey‐based beverages.     

Bioactive compounds and antioxidant activities of Brazilian hop (Humulus lupulus L.) extracts

Bioactive compounds from Brazilian hop (Humulus lupulus L.) cultivars were extracted by ultrasound and their phenolic profile compared with commercial hop from the USA. The most effective extraction conditions (solution of ethanol 49%, at 52 °C and a solid/liquid ratio of 1 g per 34 mL) for the total phenolic compounds (TPC) were determined using a Central Composite Rotatable Design. The Brazilian hop showed higher content of TPC (33.93 ± 0.67 mg GAE g⁻¹), total flavonoids (54.47 ± 0.10 mg QE g⁻¹) and higher antioxidant activity (ABTS: EC₅₀ 21.29 ± 1.36 μL mL⁻¹; DPPH: EC₅₀ 3.91 ± 0.17 μL mL⁻¹) when compared with the USA hop. The main phenolic compounds present in the extracts were the flavonoids isoquercitrin and quercetin. The antioxidant properties of the Brazilian hop extract had not been reported yet in the literature for this raw material, thus showing potential to be incorporated in polymeric films used as active packaging.     

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.     

Production,iron analysis and consumer perception of functional Thai Sinlek iron rice (Oryza sativa) drink

We produced the iron rice (IR) drink, determined the relevant chemical composition and antioxidant activity and tested the consumers’ degree of satisfaction. IR grains were digested with α-amylase and analysed chemical composition and antioxidant activity, while the hydrolysate (pH 4.0) and flavouring agents were added for final preparation of the IR drink. The IR hydrolysate contained a total iron content of 13.9 mg g⁻¹, a total phenolic content of 1.33 ± 0.07 mg gallic acid equivalent g⁻¹ and γ-oryzanol of 70.12 ± 2.7 mg kg⁻¹ rice grain, all of which inhibited the generation of free radicals in a concentration-dependent manner. The IR drink was composed of flavonoids and phenolic acids for which kaempferol was predominant. The members of all three groups of elderly subjects who consumed the low-dose IR (1.47 mg iron/100 mL), high-dose IR (2.74 mg iron/100 mL) and white rice (WR; 0.5 mg iron/100 mL) drinks expressed satisfaction and interest with the beverages at 91.2%, 100% and 88.9%, respectively. In terms of sensory evaluation, the low-dose IR drink revealed a higher acceptance rating than high-dose IR and WR (P < 0.05). Notably, the Sinlek rice drink was abundant with iron, anti-oxidative phenolics and γ-oryzanol, for which consumers expressed an overall degree of acceptance (8.1 ± 1.1).     

Mango (Mangifera indica L.) leaf extracts as ingredient for the formulation of functional beverages with biological activity

The biological activity of mango leaf extracts from different mango varieties was evaluated in terms of total phenolic content, flavonoids, antioxidant activity and inhibition of α-amylase and α-glucosidase enzymes. Leaf extract-based beverages were formulated and evaluated for some physicochemical, microbiological and sensory properties. Results indicated that the extract from 'Tommy Atkins' mango leaves had the highest total phenols content (137.08 mg of GAE g⁻¹) and antioxidant activity (DDPH = 38.26 mg TEAC 100 g⁻¹; ABTS = 59.13 mg TEAC 100 g⁻¹). The beverage formulated with 20% leaf extract presented the highest percentage of antioxidant activity (38.63%) and inhibition of enzymes α-amylase (41.9%) and α-glucosidase (37.53%). All beverages presented a yellow hue and consumers rated it with a degree of liking between 4.8 and 7.3 according to a hedonic scale. Results showed that the biological properties of beverages could be an alternative for the control of free radicals and glucose levels.     

Influence of fermentation parameters on phytochemical profile and volatile properties of mulberry (Morus nigra) wine

In the present study Box–Behnken Design was employed to analyse the effects of fermentation parameters such as temperature (T _F), pH, inoculum size (I _S) and °Brix (B_X) on total phenolic concentration (TPC), total flavonoid concentration (TFC), total anthocyanin concentration (TAC), ethanol concentration (ETHC), total higher alcohol concentration (THAC) and total ester concentration (TESC) for the development of a phytochemical‐rich wine using mulberry as a substrate. The results demonstrated that fermentation parameters significantly alter the wine characteristics. Hence, a wine with excellent consumer preference (overall acceptability of 8.51) and high concentration of phytochemicals (TPC = 6014.03 ± 27.80 mg L⁻¹, TFC = 4791.35 ± 21.22 mg L⁻¹, TAC = 1480.72 ± 5.33 mg L⁻¹) as well as good aromatic properties (ETCH =82.85 ± 0.87 g L⁻¹, THAC =249.91 ± 0.31 mg L⁻¹ and TESC =52.55 ± 0.17 mg L⁻¹) with high antioxidant activity (DPPH =220.18 mmol·l⁻¹) was obtained at optimized fermentation conditions of T _F = 25°C, pH = 4.00, I _S = 10% (v /v) and B_X = 26. The results from the present study might contribute to strengthening the development of wine containing high concentrations of phytochemical compounds with attractive olfactory attributes. Copyright © 2017 The Institute of Brewing & Distilling     

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.     

An integrated sustainable approach for the development of Kyoho skin functional tea

Kyoho (Vitis labruscana) skin is one of the valuable and eco-friendly agricultural waste and a potential source of phenolic compounds. Therefore, we attempted to develop Kyoho skin functional tea and evaluated its nutritional-functional properties as affected by drying temperatures (30, 40, 50 and 60 °C). Kyoho skin functional tea reported negligible protein (0.02 mg g⁻¹), fat (0.04–0.19%) and calories (0.36–0.70 cal g⁻¹). Total phenolic and flavonoid contents ranged from 0.25 to 0.56 mg GAE mL⁻¹ and 0.03 to 0.19 mg QE mL⁻¹, respectively. Kyoho skin functional tea showed functional properties including antioxidant activity (63.33–79.78%) and anthocyanins (0.25–0.34 mg per 100 mL). The sensory evaluation of Kyoho skin functional tea (dried at 40 °C) rated as acceptable (>6) with attractive colour (>6). Overall, these findings recommended the possibility of using Kyoho skin to develop functional teas, which may strengthen the global beverage industries.     

Evaluation of antioxidant activity of olive leaf extract obtained by ultrasound-assisted extraction and their antimicrobial activity against bacterial pathogens from food

The aim of the present study was to evaluate and compare the phenolic content and antioxidant and antimicrobial properties of olive leaf extracts obtained by ultrasound-assisted extraction (UAE) and conventional extraction (CSE). UAE of olive leaf extracts yielded a higher total phenolic content (TPC) and total flavonoid content (TFC) of 14.31% and 19.50%, respectively. Higher antioxidant activities were found from the extracts prepared with UAE (for 18.5%, 12.5%, 10.9% and 17.6% higher determined by DPPH, ABTS, FRAP and CUPRAC methods, respectively). Good antibacterial inhibitory activity (as MIC and MBC) was observed against both Y. enterocolitica and S. aureus (1.40 ± 0.40 mg mL⁻¹ and 4.00 ± 1.60 mg mL⁻¹, respectively) with the extract prepared with UAE. In conclusion, olive leaf extracts prepared with UAE exhibited higher antioxidant and antimicrobial activities against common food-borne pathogens than CSE extracts and thus could be beneficial in ensuring food quality and food safety.     

Growth and viability of Lactobacillus acidophilus NRRL B-4495, Lactobacillus casei NRRL B-1922 and Lactobacillus plantarum NRRL B-4496 in milk supplemented with cysteine,ascorbic acid and tocopherols

The effect of three reducing agents (RAs), l-cysteine, ascorbic acid, and tocopherols, on the growth of Lactobacillus acidophilus, Lactobacillus casei, or Lactobacillus plantarum during milk fermentation was evaluated. pH, redox potential, and Lactobacillus counts were determined until pH ≈ 4.6. Further, the study aimed to optimise the concentration of the RAs by formulating the fermented milks with the same RA at different concentrations (0–250 mg L⁻¹ for l-cysteine or ascorbic acid and 0–15 mg L⁻¹ for tocopherols) using a Box–Behnken experimental design. After 45 days of refrigerated storage, the viability of each Lactobacillus species was maximised. We observed that the effect of RA on Lactobacillus is species dependent; ascorbic acid and tocopherols reduced the fermentation time (29%–43%), whereas l-cysteine enhanced the Lactobacillus counts (≥1 log₁₀ cfu mL⁻¹). Lactobacillus species differ in terms of oxygen sensitivity.     

Synthesis of galactooligosaccharides using sweet and acid whey as a substrate

Two commercial available lactases from Aspergillus oryzae and Kluyveromyces lactis were used to study the synthesis of galactooligosaccharides (GOS) in sweet and acid whey. At 38 g L⁻¹ initial lactose concentration, the A. oryzae enzyme gave a GOS yield of 10.91 ± 0.01% in lactose solution, 10.93 ± 0.18% in sweet whey and 11.32 ± 0.59% in acid whey. Thus, the components in whey did not influence the enzymes transgalactolytic activity. On the other hand, the K. lactis enzyme showed a strong dependence on whey type and whey concentration. At 38 g L⁻¹ initial lactose concentration, GOS yields were 10.93 ± 0.26% in lactose solution, 4.30 ± 0.17% in sweet whey and 10.56 ± 0.41% in acid whey. However, with increasing initial lactose concentration, the inhibitory effect of sweet whey was decreasing, which resulted in even higher yields than in lactose solution.     

Antioxidant potential of extracts from peels and stems of yellow-fleshed and white cassava varieties

This study focused on the exploration of the potentials of extracting antioxidants from peels and stems of yellow-fleshed and white cassava varieties. The effect of particle size (0.2 and 0.5 mm) and variety on the phenolic content and antioxidant activity was assessed. The peels of the yellow-fleshed cassava variety with a particle size of 0.2 mm showed the highest phenolic content with 681.5 GAE mg 100 g⁻¹ and antioxidant activity of 19% and 425 μM TE g⁻¹ dry matter using DPPH and FRAP assays respectively. The stems of the white cassava with a particle size of 0.2 mm exhibited high phenolic content (442.4 GAE mg 100 g⁻¹) and antioxidant activity of 12.8% and 234 μM TE g⁻¹, better than the stem of the yellow-fleshed cassava. These results indicate that phenolic and antioxidant extractions were influenced by variety, the plant parts and particle size for the antioxidant assays.     

Development of low-alcohol isotonic beer by interrupted fermentation

Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L⁻¹), osmolality (mOsmol kg⁻¹), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L⁻¹ gallic acid), reducing and total sugars (%) and Na and K contents (mg L⁻¹). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences.     

Bioactive compounds,antioxidant activity and sensory properties of Tarhana,a traditional fermented food,enriched with pickling herb (Echinophora tenuifolia L.)

The addition of pickling herb (Echinophora tenuifolia L.; PHET) resulted in increase in the total phenolic and flavonoid contents in Tarhana in both free and bound fractions' extracts. The antioxidant activity of Tarhana containing 2%, 6% and 18% PHET was 81.45–81.72% in bound fraction whereas in free fraction it was up to 88.27% (6% PHET). The gallic acid contents of Tarhana with PHET in free fraction were between 0.49 mg L⁻¹ (10%) and 2.75% (14%) and that in bound fraction varied between 0.36 mg L⁻¹ (10%) and 3.61 mg L⁻¹ (18%). Statistically significant differences (with control) were observed among the contents of individual phenolic compounds in free and bound fractions of Tarhana depending on PHET concentrations. The addition of higher PHET contents in Tarhana showed negative effects hence, a low concentration (2%) of PHET is recommendable for Tarhana with enhanced nutritional properties.     

Effect of drying kinetics on main bioactive compounds and antioxidant activity of acerola (Malpighia emarginata D.C.) residue

This study investigates the drying kinetics of residue of acerola, in a fixed‐bed dryer, analysing the effect of the process variables on the antioxidant properties of the residue. A complete factorial design 3² has been performed, where the independent variables studied were as follows: air velocity (0.5, 1.0 and 1.5 m s^?1) and air‐drying temperature (40, 50 and 60 °C). The bioactive compounds studied were L‐ascorbic acid, total phenolic, total flavonoids and antioxidant activity (expressed as IC₅₀) was determined using free radical DPPH^?. Both independent variables studied have shown to be statistically significant. The content of ascorbic acid was the highest at 60 °C and 1.0 m s^?1 (126.2 ± 0.004 mg 100 g^?1) while for the fresh residue 16.12 ± 0.003 mg 100 g^?1, whereas the total phenolic showed the highest content at 50 °C and 1.5 m s^?1 (46.2 ± 0.003 mg gallic acid.100 g^?1) while for the fresh residue 12.59 ± 0.001 mg gallic acid.100 g^?1. The drying conditions play an important role in determining the final quality of the product mainly in terms of antioxidant activity.     

Development of rapid and highly specific TaqMan probe-based real-time PCR assay for the identification and enumeration of Lactobacillus kefiri in kefir milk

Lactobacillus kefiri is one of the key functional lactic acid bacteria in kefir milk. We designed a novel real-time PCR primer/probe set, LK_508 targeting the recA gene, for the rapid identification and enumeration of L. kefiri. In inclusivity and exclusivity test using standard strains and kefir isolates, only the 9 tested L. kefiri strains were positive, with the remaining 38 closely related microorganisms testing negative, thus indicating 100% sensitivity and specificity of the assay. The population of L. kefiri was 3.77, 4.30, 4.79, and 5.63 log cfu mL⁻¹ of kefir milk fermented at 25 °C with 5% grain-milk ratio for 12, 24, 36, and 48 h, respectively. The newly developed qPCR assay could be applied to investigate the quantitative relationship of kefir microbiota in fermentation process.     

Available lysine,protein digestibility and lactulose in commercial infant formulas

Available lysine, in vitro protein digestibility and lactulose values were determined in 23 commercial infant formulas. The mean available lysine content of the formulas based on dairy proteins was 66.7±9.5 mg g⁻¹ protein, similar to that of human milk, while that of soy based formulas was considerably lower (45.0±8.3 mg g⁻¹ protein). In vitro protein digestibility values ranged 85.5–88.9% for soy-based formulas and 90.5–98.3% for formulas based on dairy proteins. Formulas based on milk enriched with whey had higher lactulose content than those based on cow's milk. However, all values were below the limit of 600 mg L⁻¹ recommended for UHT milk.     

Generation of phenolic-rich extracts from brewers' spent grain and characterisation of their in vitro and in vivo activities

Brewers' spent grain (BSG) is a co-product of the brewing industry, which is rich in phenolic acids. This study compared the in vitro bioactive properties of aqueous, aqueous pH-shift and enzyme-aided phenolic extracts from pale (unroasted) wet BSG. Overall, the pH-shift extracts showed higher oxygen radical absorbance capacity (ORAC), trolox equivalent antioxidant capacity (TEAC) and ferric-reducing antioxidant power (FRAP) values compared with the enzyme-aided extracts. A selected enzyme-aided extract showed highest in vitro ACE inhibitory activity (ACE IC₅₀: 0.133 ± 0.032 mg mL⁻¹) and mediated significant (p < 0.05) reductions in blood pressure markers in vivo following ingestion by spontaneously hypertensive rats (systolic blood pressure; −35.35 ± 9.04 and diastolic blood pressure; −28.55 ± 4.22 mmHg). The results demonstrated that the observed in vitro activity of phenolic-rich extracts may be translated into an in vivo hypotensive effect. Enzyme-assisted extraction has potential as an alternative solvent-free approach for generating phenolic-rich extracts from BSG that may find use in the management of hypertension.     

Evaluation of furosine,lactulose and acid-soluble β-lactoglobulin as time temperature integrators for whipping cream samples at retail in Austria

Three heat load indicators, i.e., furosine, lactulose and acid-soluble β-lactoglobulin, were determined in whipping cream samples purchased from Austrian market (n = 33), as well as commercial samples obtained directly from one Austrian dairy company (one brand, n = 25). Furosine contents were 47.8 ± 14.0, 72.2 ± 36.6, and 172.5 ± 17.7 mg 100 g⁻¹ protein, and β-lactoglobulin contents were 143 ± 91, 195 ± 150, and 89 ± 31 mg L⁻¹ for retailed pasteurised, extended shelf life (ESL), and ultra-high temperature (UHT) cream samples, respectively. Lactulose concentrations (analysed enzymatically) were 29 ± 10, 56 ± 41, and 201 ± 24 mg L⁻¹ for pasteurised, ESL and UHT cream samples, respectively. Linear correlation obtained for furosine and lactulose concentrations indicated that these indicators can reliably assess the heat load of pasteurised, ESL and UHT cream samples, whereas β-lactoglobulin was definitely not appropriate to discriminate between these heating categories.