Evaluation of yogurt and various beverages as carriers of lactic acid bacteria producing 2-branched (1,3)-β-D-glucan

Probiotic cultures are increasingly being incorporated into a wide variety of food products. Although lactobacilli and bifidobacteria are the most frequently used, other lactic acid bacteria (LAB) have been reported to be potential probiotics. Of these, the cider isolates Pediococccus parvulus (strains 2.6 and CUPV22) and Lactobacillus suebicus CUPV221 produce a 2-branched (1,3)-β-d-glucan exopolysaccharide that decreases serum cholesterol levels and affects the activation of human macrophages. For this reason, these 3 strains were incorporated into yogurt, orange juice, and 2 juice-milk beverages to evaluate the effect of the food matrix on the resistance of these strains to simulated gastrointestinal tract conditions. Our results showed that incorporation of the LAB did not significantly affect the physical and rheological properties of the food matrices tested. When incorporated in yogurt, LAB strains population decreased by 2 to 3 log orders of magnitude during the shelf life of the product (28 d). However, no significant decrease was observed in the juice and juice-milk beverages during the same storage period, except for Lb. suebicus, whose viability decreased by 3 log orders of magnitude. When strains were subjected to gastrointestinal tract conditions, a decrease in the survival was observed at the lower pH (1.8). However, incorporation of these LAB strains into orange juice increases their resistance to lower pH conditions, thus improving survival to gastrointestinal stress. Moreover, a protective effect was observed for P. parvulus CUPV22 and 2.6 to gastric stress in juice-milk beverages and to gastrointestinal stress in yogurt. Lactobacillus suebicus CUPV221 did not survive when incorporated into yogurt and juice-milk beverage.     

Do street food vendors sell a sufficient variety of foods for a healthful diet? The case of Nairobi

This study examined whether street food vendors sell a sufficient variety of foods for a healthful diet. It was hypothesized that vendors sold only low-cost food groups to enable the buyer to afford the food while the vendor also made a profit. A structured questionnaire was administered to 580 vendors in three selected locations. Data included product names, ingredients, methods of preparation, and the sex of the vendor. A little more than half of the vendors (53%) sold food of only one group; 44% sold cereals. Overall, 36% of vendors, mostly men, sold only carbohydrate products. The percentage of vendors selling foods of more than one group was higher in the working area (53%) than in the slum area (43%, p < .05), and it was higher in both of these areas taken together than in the lower-middle income area (21%, p < .001). Micronutrient and mixed-nutrient products were associated with female vendors. Although a slight majority of all street vendors sell foods of only one group, women vendors are capable of supplying a sufficient variety of food groups that consumers can afford. It appears that consumer purchasing power dictates the food groups provided by vendors, especially cereal-based-foods. A policy on micronutrient fortification of cereal flours and fats used in popular street food preparation needs to be considered. This could be coupled with consumer and vendor education programs focusing on the importance of healthful diets.     

Synthesis and controlled-release properties of chitosan/β-Lactoglobulin nanoparticles as carriers for oral administration of epigallocatechin gallate

A nano-sized double-walled carrier composed of chitosan and β-lactoglobulin (β-Lg) for oral administration of epigallocatechin gallate (EGCG) was developed to achieve a prolonged release of EGCG in the gastrointestinal tract. Carboxymethyl chitosan (CMC) solution was added dropwise to chitosan hydrochloride (CHC) containing EGCG to form a primary coating by ionic complexation. Subsequently, β-Lg was added to create a secondary layer by ionic gelation. The obtained EGCG-loaded chitosan/β-Lg nanoparticles had sizes between 100 and 500 nm and zeta potentials ranging from 10 to 35mV. FT-IR spectroscopy revealed a high number of hydrogen-bonding sites in the nanoparticles, which could incorporate EGCG, resulting in high encapsulation efficiency. EGCG incorporated in the primary coating was released slowly over time by diffusion from the swollen CMC-CHC matrix after the outer layer of β-Lg was degraded in the intestinal fluid. The sustained-release property makes chitosan/β-Lg nanoparticles an attractive candidate for effective delivery of EGCG.     

Oxygen tension measurement as a means of detecting incipient spoilage of raw milk by psychrotrophic bacteria?

A large fall (89% to 10% saturation) in the oxygen tension of raw milk incubated with constant aeration and agitation at 7°C in a fermenter was observed to occur prior to the onset of extracellular protease and lipase production by microorganisms. This same pattern with respect to oxygen tension and lipase production was also observed when raw milk samples from creamery silos were incubated at 7°C in an orbital incubator. The results are in agreement with earlier fermenter studies in which strains of Pseudomonas fluorescens were grown in a simulated milk medium at 7°C. Measurement of oxygen tension may be able to be used to detect incipient enzyme-mediated spoilage of raw milk by psychrotrophs.     

(1-3)(1-6)-β-glucan-enriched materials from Lentinus edodes mushroom as a high-fibre and low-calorie flour substitute for baked foods

BACKGROUND: Extensive physiological and biological emphasis has been placed on pharmaceutical and medicinal uses of mushrooms containing β‐glucans, but their incorporation into processed functional foods is quite limited. Thus, low‐grade Lentinus edodes mushrooms were utilised to produce β‐glucan‐enriched materials (BGEMs), which were evaluated as a high‐fibre and low‐calorie substitute for wheat flour. RESULTS: The fractions obtained from Lentinus edodes mushrooms contained 514 g kg^?1 of (1–3)‐β‐glucans with (1–6)‐β‐linked side chains and the chemical structure was confirmed by ¹³C NMR and FTIR spectroscopy. Replacement of a portion of the wheat flour with BGEMs resulted in the solutions with lower values of pasting parameters and also caused significant changes in starch gelatinisation. When BGEMs were incorporated into cake formulations, batter viscosity increased with more shear‐thinning behaviours and elastic properties improved. Overall, the cakes containing more BGEMs showed decreased volume and increased hardness while no significant differences were observed between the control and BGEM cakes containing 1 g of β‐glucan per serving. CONCLUSION: As a wheat flour substitute, the BGEMs that were prepared from low‐grade Lentinus edodes mushrooms, could be successfully used to produce cakes containing 1 g of β‐glucan per serving with quality attributes similar to those of the control. Copyright © 2011 Society of Chemical Industry     

High γ-aminobutyric acid production from lactic acid bacteria: Emphasis on Lactobacillus brevis as a functional dairy starter

γ-Aminobutyric acid (GABA) and GABA-rich foods have shown anti-hypertensive and anti-depressant activities as the major functions in humans and animals. Hence, high GABA-producing lactic acid bacteria (LAB) could be used as functional starters for manufacturing novel fermented dairy foods. Glutamic acid decarboxylases (GADs) from LAB are highly conserved at the species level based on the phylogenetic tree of GADs from LAB. Moreover, two functionally distinct GADs and one intact gad operon were observed in all the completely sequenced Lactobacillus brevis strains suggesting its common capability to synthesize GABA. Difficulties and strategies for the manufacture of GABA-rich fermented dairy foods have been discussed and proposed, respectively. In addition, a genetic survey on the sequenced LAB strains demonstrated the absence of cell envelope proteinases in the majority of LAB including Lb. brevis, which diminishes their cell viabilities in milk environments due to their non-proteolytic nature. Thus, several strategies have been proposed to overcome the non-proteolytic nature of Lb. brevis in order to produce GABA-rich dairy foods.     

Complex formation of a 4-α-glucanotransferase using starch as a biocatalyst for starch modification

Food Science and Biotechnology - A 4-α-glucanotransferases from Thermus thermophilus (TTαGT) possesses an extra substrate binding site, leading to facile purification of the intact enzyme...     

Chemical composition of the cell wall of probiotic and brewer’s yeast in response to cultivation medium with glycerol as a carbon source

The structure of cell wall of yeasts (genus Saccharomyces) is one of the factors that determine their health-promoting properties connected to the presence of β-glucans and mannoprotein. The aim of the study was to determine the influence of glycerol as a carbon source on structural polymers of cell wall (β-glucan and mannoprotein) of probiotic yeasts Saccharomyces cerevisiae var. boulardii and brewer’s yeasts S. cerevisiae R9. Significant increase of the percentage of polysaccharide content in the cell wall dry weight of S. cerevisiae R9 brewer’s yeasts was noted (in the range of 10–20 %) after cultivation in medium containing glycerol at a concentration of 2–5 % and pH 4.0. The highest content of carbohydrates in probiotic yeasts’ cell wall (58 %) was observed after cultivation in medium containing 3 % of glycerol and pH 5.0. The cell wall of probiotic yeasts was characterized by higher content of mannoprotein comparing with cell wall preparation of brewer’s yeasts S. cerevisiae R9 composed mainly of β-glucans. After cultivation in mediums with 2 and 3 % of glycerol, the cell of brewer’s yeasts contained the highest amount of β(1,3/1,6)-glucan in dry weight of the cell wall (about 36 %). Glycerol at a concentration of 3 and 5 % also intensified mannoprotein biosynthesis in cell wall of S. cerevisiae R9, approximating their content to those noted in the cells of probiotic yeasts (about 29 % (w/w) of dry weight of the cell wall) after cultivation in a medium of pH 5.0 containing 3 % of glycerol.     

Encapsulated whey–native yeast Kluyveromyces marxianus as a feed additive for animal production

ABSTRACT

Whey is the main byproduct of the cheese industry. While the composition is variable, it retains up to 55% of milk nutrients. The beneficial features of whey indicates a promising source of new potentially probiotic strains for the development of food additives destined for animal production. The aim of this study was to identify Kluyveromyces spp. isolated from whey, to study some probiotic properties and to select the best strain to be encapsulated using derivatised chitosan. Kluyveromyces marxianus strains (VM003, VM004 and VM005) were isolated from whey and identified by phenotypic and molecular techniques. These three yeast strains were able to survive under gastrointestinal conditions. Moreover, they exhibited weak auto-aggregation and co-aggregation with pathogenic bacteria (Salmonella sp., Serratia sp., Escherichia coli and Salmonella typhimurium). In general the K. marxianus strains had a strong antimicrobial activity against pathogenic bacteria. The potential probiotic K. marxianus VM004 strain was selected for derivatised-chitosan encapsulation. Material treated with native chitosan exhibited a strong antimicrobial activity of K. marxianus, showing a total growth inhibition at 10 min exposure. However, derivatised-chitosan encapsulation showed a reduced antimicrobial activity. This is the first study to show some probiotic properties of whey–native K. marxianus, in vitro. An encapsulation strategy was applied using derivatised chitosan.     

Forest biomass waste as a potential innovative source for rearing edible insects for food and feed – A review

Worldwide, huge quantities of organic wastes are generated annually in the forest industry, but most of these wastes are discarded. Only a minor proportion is used, mainly for biofuel and secondarily for compost production. Simultaneously, demand for more and new food products is increasing due to rapid growth in the global population. In recent years, use of edible insects has been proposed as one promising solution to an upcoming food supply crisis. The rearing of insects for human food and livestock feed has some significant advantages, like high protein content, effective feed conversion rate, low greenhouse gas emissions and low water requirements. The aim of this review was to compile up-to-date information on rearing edible insects for food and feed and to investigate the potential use of forest biomass waste as a new substrate for insect rearing.     

Agar-immobilized basil–lactic acid bacteria bioproducts as goat milk taste-masking agents and natural preservatives for the production of unripened goat cheese

Goat milk cheeses have become popular recently; however, many consumers do not choose these products because they have specific sensory properties that are not acceptable to all consumers and the shelf life of the cheese is short. The concept of this work was to increase overall acceptability and shelf life of unripened goat milk cheese by using Ocimum basilicum and lactic acid bacteria (Lactobacillus plantarum LUHS135, Lactobacillus paracasei LUHS244, Pediococcus pentosaceus LUHS100, Pediococcus acidilactici LUHS29, and Lactobacillus brevis LUHS140) bioproducts (basil-LAB) immobilized in agar. A basil-LAB bioproduct could be a promising multifunctional ingredient for cheese manufacturing because it has a low pH, high LAB count, and high total phenolic compound content (after fermentation pH decreased by 25.4%, LAB count averaged 7.2 log₁₀ cfu/g, and total phenolic compound content increased by 30.9%). Use of different LAB in the preparation of basil-LAB bioproducts had a significant influence on cheese pH and hardness, and compared with cheese samples prepared with nonfermented basil, cheese samples prepared with basil-LAB bioproducts had, on average, higher pH (by 2.6%) and lower hardness (by 36.0%), similar to the control cheese (without basil). Overall acceptability of cheese was significantly influenced by the basil-LAB bioproduct immobilization process; in all cases, cheese samples prepared with fermented and immobilized basil-LAB bioproduct had better acceptability (5 points). After 120 h of storage, cheese samples prepared with basil-LAB bioproducts fermented with LUHS135, LUHS244 and LUHS140, no enterobacteria were found, and we detected strong negative and moderate negative correlations, respectively, of LAB count with enterobacteria count and yeast/mold count (r = ?0.7939 and r = ?0.4495, respectively). Finally, immobilization increased LAB viability in fresh goat milk cheese, which led to a reduction in enterobacteria and mold/yeast contamination during storage and an increase in overall acceptability compared with nonimmobilized basil-LAB. Therefore, basil-LAB bioproducts fermented with LUHS135, LUHS244, and LUHS140 strains can be recommended for preparing fresh goat milk cheese with extended shelf life and high acceptability.     

A method for the determination of acrylamide in a broad variety of processed foods by GC–MS using xanthydrol derivatization

A novel GC–MS method was developed for the determination of acrylamide, which is applicable to a variety of processed foods, including potato snacks, corn snacks, biscuits, instant noodles, coffee, soy sauces and miso (fermented soy bean paste). The method involves the derivatization of acrylamide with xanthydrol instead of a bromine compound. Isotopically labelled acrylamide (d ₃-acrylamide) was used as the internal standard. The aqueous extract from samples was purified using Sep-Pak? C₁₈ and Sep-Pak? AC-2 columns. For amino acid-rich samples, such as miso or soy sauce, an Extrelut? column was used for purification or extraction. After reaction with xanthydrol, the resultant N-xanthyl acrylamide was determined by GC–MS. The method was validated for various food matrices and showed good linearity, precision and trueness. The limit of detection and limit of quantification ranged 0.5–5 and 5–20?µg?kg^?1, respectively. The developed method was applied as an exploratory survey of acrylamide in Japanese foods and the method was shown to be applicable for all samples tested.     

Utilization of sprout‐damaged wheat as raw material for sour dough pre‐ferments with mixed cultures of lactic and propionic acid bacteria

The utilization of sprout‐damaged wheat flour in pre‐fermentation for sour dough bread‐baking increased lactic acid formation and titratable acidity several fold in comparison to the use of baker's wheat flour, and also resulted in a lactic acid to acetic acid molar ratio acceptable for sour dough bread. Further, enzymic treatment of the sprout‐damaged wheat flour with malted grain flour appared to be necessary for a properly balanced acid formation although the α‐amylase activity of sprout‐damaged wheat flour was quite high. The accumulation of lactic acid in the pre‐ferment decreased in the presence of yeast, and thus the molar ratio of lactic to acetic acid could be adjusted suitable for sour bread‐baking even with homofermentative lactic acid bacteria. Finally, when using mixed culture pre‐ferments of Lactobacillus brevis and Propionibacterium jensenii, at least 0.1% of propionic acid (based on flour weight), sufficient to prevent mold growth in the final bread, was obtained.     

Bisphenol A contamination in soft drinks as a risk for children’s health in Italy

Bisphenol A (BPA) was determined in sugary carbonated, non-carbonated and milk-based beverages, through HLPC-fluorescence detection and confirmed by LC-MS/MS, in a selection of brands that are mostly consumed by Italian children. The daily intake was determined through the WHO budget method (BM). BPA was found at detectable levels in 57% of carbonated beverages, in 50% of non-carbonated and in 100% of milk-based beverages. The median concentrations were 1.24 µg l^–1 (range = < LOD–4.98 µg l^–1) in canned carbonated beverages and 0.18 µg l^–1 (< LOD–1.78 µg l^–1) in non-canned carbonated beverages. In non-carbonated beverages, median concentrations were 0.80 µg l^–1 (< LOD–2.79 µg l^–1) and 0.18 µg l^–1 (< LOD–3.58 µg l^–1), respectively, for canned and non-canned beverages; in milk-based products the BPA median concentration was 3.60 µg l^–1 (1.00–17.65 µg l^–1). BPA daily intake from sugary drink consumption in children ranged from 0.008 to 1.765 µg kg^–1 bw day^–1. The median exposure values for the ‘best’ and ‘worst’ cases were 0.16% and 0.47% respectively of the EFSA t-TDI for BPA (4 µg kg^–1 bw day^–1), and 10.59% and 35.30% of the t-TDI when the maximum levels were considered.     

Improvement of the stability of nattokinase using γ-polyglutamic acid as a coating material for microencapsulation

In this study, nattokinase (NK) was microencapsulated in high-molecular-weight Na-γ-PGA, and the amount of NK added to the Na-γ-PGA was in the ratio of 1:1 and 2:1 w/w, which was designated as NK-100 and NK-200, respectively. The temperature and pH stability of microencapsulated NK were found to be higher than those of the free form. Free NK lost its overall initial activity after treatment at a temperature above 60 °C or at a pH less than 5.0 for 1 h. NK-100 and NK-200 retained 35% and 60% of their activities after exposure to an acidic condition of pH 4.0 and possessed 18% and 25% activity after treatment at 60 °C for 1 h, respectively. Furthermore, NK-100 and NK-200 exhibited more protective bioactivity than free NK did in storage stability tests. This simple and versatile approach can be potentially applied to the microencapsulation of various biomolecules for drug-delivery applications.     

Barley β-glucan aerogels as a carrier for flax oil via supercritical CO2

Flax oil has important implications in human health, however, it must be protected in food systems to maintain bioactivity and avoid rancidity. Impregnation of active compounds in polymer networks using supercritical CO₂ (SCCO₂) has shown potential for their protection and delivery. Aerogels were formed with barley β-glucan using SCCO₂ drying. Impregnation of flax oil in barley β-glucan aerogels using SCCO₂ was evaluated when oil was added at different stages of the drying process (before, during and after drying) and under static and dynamic processes at different processing times (2, 6 and 8 h), temperatures (40 and 60 °C) and pressures (15 and 30 MPa). Impregnated aerogels were analyzed using Fourier-transform infrared spectrometry and scanning electron microscopy. Addition of oil during the drying process and the use of a dynamic flow regime resulted in the highest loading of aerogels. Oil loading increased with processing time, from 47.79% (lipid as % of total impregnated aerogel mass) after 4 h to 60.96% after 8 h, and with increasing pressure. Aerogel impregnation using SCCO₂ has potential as a delivery vehicle for high-value food grade compounds, including flax oil.