Encapsulation of Lactobacillus rhamnosus in double emulsions formulated with sweet whey as emulsifier and survival in simulated gastrointestinal conditions

Lactobacillus rhamnosus cultured in sweet whey and harvested in the late log phase was entrapped in the inner aqueous phase of a double water-in-oil-in-water emulsion using concentrated sweet whey as emulsifier. The primary and double emulsion droplets showed practically no changes in their morphology and droplet size with aging time. The viability of the entrapped L. rhamnosus in the double emulsion was compared to that of non-entrapped control cells exposed to low pH and bile salt conditions. The viability of the control cells (initial number = 6.57 ± 0.3 log cfu ml^?1) decreased significantly under low pH and bile salt conditions, and their survival was 71% and 89%, respectively. The survival of the entrapped cells (initial number = 6.74 ± 0.2 log cfu ml^?1) increased significantly under low pH and bile salt conditions, and their survival was 108% and 128%, respectively. It is concluded that the double emulsion protected L. rhamnosus against simulated gastrointestinal tract conditions.     

Application of shellac for the development of probiotic formulations

In this study, we have improved the enteric properties of shellac and developed probiotic formulations comprising this natural polymer. The effects of plasticizers such as glycerol and glyceryl triacetate, as well as water-soluble polymers such as sodium alginate, hydroxypropyl methylcellulose and polyvinylpyrrolidone on thermodynamic characteristics and coating properties of shellac were evaluated. The data indicate that glycerol showed the best plasticization effect. Hydroxypropyl methylcellulose and polyvinylpyrrolidone had superior miscibility with shellac compared to sodium alginate. Then, three fluid-bed dried bacterial species i.e., Enterococcus faecium, Bifidobacterium bifidum and Lactobacillus reuteri, were coated with formulations comprising different concentrations of shellac and additives. Coatings with shellac containing 5% glycerol or 5% sodium alginate or up to 20% [w/w] polyvinylpyrrolidone protected the microorganisms against acidic pH and provided the best release profile in simulated intestinal fluid. Moreover, these formulations maintained promising cell survival rates after four months of storage at 5 °C. E. faecium and B. bifidum showed more resistance to manufacturing process than L. reuteri.     

Influence of high intensity ultrasound on microbial reduction,physico-chemical characteristics and fermentation of sweet whey

The aim of this study was to investigate the influence of high intensity ultrasound on quality of reconstituted sweet whey in order to substitute thermal treatments i.e. pasteurization. Also, it was intended to study the influence of ultrasound on fermentation process of pasteurized or thermo-sonicated whey with respect to culture activation and sensory properties of the fermented whey. In the first stage, whey was subjected to treatments with different power inputs (480 W, 600 W) over 6.5, 8 and 10 min at constant temperature (45 °C, 55 °C). Treated whey samples were analyzed for microbiological quality, particle size distribution, protein content, acidity, electrical conductivity, viscosity and sensory properties. All of the analyzed parameters were compared with the control sample (pasteurized) and fresh whey. Subsequently, influence of high intensity ultrasound on pasteurized or thermo-sonicated whey fermentation with yoghurt culture and with monoculture Lactobacillus acidophilus La-5 was investigated. Ultrasound treatments were applied for culture activation prior to or after the inoculation. Whey thermo-sonication by nominal power of 480 W for 10 min at 55 °C resulted in better microbiological quality and sensory properties in comparison to whey pasteurization. Ultrasound treatments with nominal input power of 84 W over 150 s resulted in the highest increase of the viable count during the activation process. Whey fermentation by ultrasonicated culture La-5 lasted 30 min shorter and resulted in higher viable cells count.Industrial relevanceAttached paper (“Influence of high intensity ultrasound on microbial reduction, physico-chemical characteristics and fermentation of sweet whey”) reports the influence of high intensity ultrasound on quality and fermentation process of sweet whey. Also, the influence of high intensity ultrasound on pasteurized or thermo-sonicated whey fermentation with yoghurt culture and with monoculture Lactobacillus acidophilus La-5 was investigated.Whey proteins are thermo-labile proteins and degradable at higher temperatures (above 60 °C), and at conventional processing (pasteurization), denaturation and precipitation of proteins occur. Ultrasound gives a great replacement for pasteurization where precipitation does not occur. Also, ultrasonic treatment of the whey results in homogenization and thus, stability is increased. When microbiological cultures for fermentation, prior to the inoculation in the samples, are treated by ultrasound their activity is higher (explained in the paper) and thus fermentation is faster.From an economical point of view, processing by ultrasound can reduce costs a lot, since fermentation time is shorter, and the same effect as pasteurization is achieved. Ultrasonic treatment is a future in the dairy industry.     

Improving ambient temperature stability of probiotics with stress adaptation and fluidized bed drying

Stabilization efficiency in terms of long term ambient temperature storage viability of the probiotic strain Lactobacillus casei CRL 431 was compared using freeze and fluidized bed drying techniques. Fluidized bed drying was able to retain 2.5 log cfu/g higher viability after 52 weeks of storage at 25 °C. A combination of fluidized bed drying and osmotic stress adaptation to the probiotic cells yielded further improvement of 0.83 log cfu/g higher viability compared to the unstressed cells. The findings were validated with other two lactobacilli and two bifidobacterium strains with probiotic characteristics and significant improvements in storage stability over freeze dried samples were observed. Fortification of vitamin E in the stabilization matrix as an antioxidant improved the stability by 0.18 log cfu/g during 20 weeks storage period at 25 °C, whereas any similar benefit of fortifying inulin as a prebiotic was not observed.     

Biopolymer nanoparticles as potential delivery systems for anthocyanins: Fabrication and properties

Biopolymer nanoparticles and microparticles may be used as delivery systems for bioactive compounds in food and pharmaceutical applications. In this study, biopolymer nanoparticles were assembled from whey protein isolate (WPI) and beet pectin (BP) using thermal processing and electrostatic complexation. This approach involved mixing the two biopolymers at pH 5.8, heating (90 °C, 5 min) to induce protein nanoparticle formation and then adjusting the solution to pH 4.0 to promote coating of the protein nanoparticles with pectin. This process led to the formation of relatively small anionic biopolymer nanoparticles (d < 200 nm) at pH 4. The biopolymer particles had a high negative charged from pH 8 to 4.0 but became less anionic at lower pH values. The mean particle diameter was relatively small (d < 200 nm) around pH 4.0 but increased appreciably at lower and higher pH due to particle flocculation. The biopolymer nanoparticles were loaded with an anthocyanin-rich extract. A higher loading efficiency was observed when anthocyanin was added before heating the WPI-BP solution (LE = 55%) rather than after (LE = 35%), which was attributed to increased protein–polyphenol interactions. The encapsulation of anthocyanins within biopolymer particles improved their heat stability. However, encapsulated anthocyanin had a lower antioxidant activity than non-encapsulated anthocyanin, which was attributed to the thermal processing step required during particle fabrication and the binding of anthocyanins to biopolymers within the nanoparticles. Color measurements indicated that the encapsulation of anthocyanin within biopolymer particles did not inhibit its degradation after ascorbic acid addition. Overall, our results show that the encapsulation of anthocyanins within the biopolymer particles fabricated in this study was not particularly effective at improving their antioxidant activity or color stability. Alternative strategies are therefore needed to encapsulate this important color and nutraceutical agent.     

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%).     

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.     

Microbial transformation of tectoridin from Pueraria flos by Lactobacillus and bifidobacteria

Tectoridin could be hydrolyzed to tectorigenin by β-glucosidase-producing intestinal bacteria. In this study, nine strains of Lactobacillus and bifidobacteria were screened for high levels of β-glucosidase activity. We investigated their ability to transform tectoridin from Pueraria flos to tectorigenin. Lactobacillus reuteri DSM20016 showed the highest cell-envelope associated β-glucosidase activity, whereas the intracellular β-glucosidase activity from Bifidobacterium adolescentis ATCC15703 was higher than the other screened bacterial strains. L. reuteri DSM20016, Lactobacillus rhamnosus GGB41031 and B. adolescentis ATCC15703 showed high bioconversion rate of tectoridin. L. reuteri DSM20016 showed the highest bioconversion efficiency of tectoridin, 100% tectoridin was hydrolyzed and there was an approximate 185-fold increase in the concentration of tectorigenin after 24 h. The present study suggests that L. reuteri DSM20016, L. rhamnosus GGB41031 and B. adolescentis ATCC15703 have great potential for converting tectoridin from Pueraria flos to more bioactive tectorigenin.     

Transglutaminase-induced caseinate gelation for the microencapsulation of probiotic cells

A novel method for the encapsulation of probiotic cells in foodgrade casein microcapsules was developed. The process is based on a transglutaminase-catalysed gelation of casein suspensions containing probiotic cells. Water insoluble, spherical capsules with a volume-based median diameter of 165 ± 23 μm resulted from the process. Encapsulation yields of 70 ± 15% and 93 ± 22% were achieved for Lactobacillus paracasei ssp. paracasei F19 and Bifidobacterium lactis Bb12, respectively. Analysis of living cell numbers after incubation of free and encapsulated probiotics in simulated gastric juice without pepsin at pH 2.5 and pH 3.6 (37 °C, 90 min) showed a protective effect due to microencapsulation under all conditions tested. The study indicates that transglutaminase-induced caseinate gelation can be applied to the microencapsulation of probiotics. Furthermore, it could be shown that an entrapment in a dense casein matrix can protect these microorganisms from damage due to pH-levels similar to those in the human stomach.     

Surface Tension of Whey and Whey Derivatives

The surface tension of various whole wheys, solutions of component whey proteins, UF fractions, and the effect of heating on the surface tensions of these solutions were determined using the Wilhemy plate method. The mean surface tension of three commercial cottage cheese wheys, a commercial cheddar cheese whey, and a laboratory rennet whey was found to be 41.7 ± 1.2 dyne/cm (25°C) and did not vary significantly with the type of whey despite differences in both pH and protein content. The surface tensions of aqueous solutions of individual pure protein fractions of whey (serum albumin, β-lactoglobulin, α-lactalbumin, and gammaglobulins), in concentrations approximating normal whey contents, were significantly different and greater than for the whole wheys.Heating of individual protein solutions at 80°C for 50 min produced insignificant changes in measured surface tension despite producing protein precipitation in some of the solutions. Similar heating of the whole whey solutions resulted in a significant decrease in surface tension and marked precipitation in most cases.The fractionation of the wheys into UF permeates and retentates resulted in a retentate fraction of significantly lower surface tension than for UF permeates. Heating increased the surface tension of retentate fractions while the permeate fractions showed a decrease.     

Effect of temperature on growth and metabolism of probiotic bacteria in milk

The growth and metabolism of six probiotic strains with documented health effects were studied in ultra-high temperature (UHT) treated milk supplemented with 0.5% (w/v) tryptone or 0.75% (w/v) fructose at different temperatures. The probiotic strains were Lactobacillus acidophilus La5, Lb. acidophilus 1748, Lb. johnsonii LA1, Lb. rhamnosus GG, Lb. reuteri SD 2112 and Bifidobacterium animalis BB12. Fermentation was followed for 48 h at 20, 30, 37 and 45 °C and the samples were analysed for pH, log cfu mL⁻¹, volatile compounds, organic acids and carbon dioxide. All six probiotic strains showed very different profiles of metabolites during fermentation, however, the two Lb. acidophilus strains were the most alike. All strains, except Lb. reuteri SD 2112, showed viable cell numbers above 6.5 log cfu mL⁻¹ after 48 h fermentation at 30, 37 and 45 °C. The probiotic strains produced different amounts of metabolic products according to temperature and fermentation time illustrating the importance of controlling these parameters.     

Comparison of subjective grading and objective assessment in meibography

AimTo analyse repeatability of subjective grading and objective assessment in non-contact infra-red meibography.MethodsMeibography photographs of 24 subjects (female 14; mean age = 46; range = 19–69 years, upper-lid images = 12, lower-lid images = 12) were classified in two sessions by three experienced observers (OI, OII, OIII). Relative area or portion affected by meibomian glands (MG) loss was classified applying three different grading scales in randomized order: a four-grade scale (4S) (degree 0 = no partial glands; 1 = <25% partial glands; 3 = 25–75% partial glands; 3 = >75% partial glands), a pictorial five-grade scale (5S) (degree 0 = no meibomian gland loss (MGL); 1 = <25% MGL; 3 = 26–50% MGL; 3 = 51–75%; 4 = >75% MGL) and objectively by a 100-grade scale (DA) applying ImageJ software.ResultsObserved MG loss ranged from 0% to 69%. Intra-observer agreement of the 5S (OI: κ = 0.80, p < 0.001; OII: κ = 0.40, p = 0.009; OIII κ = 0.81, p < 0.001) was better than of the 4S (OI: κ = 0.79, p < 0.001; OII: κ = 0.15, p = 0.342; OIII κ = 0.50, p = 0.0071). Intra-observer agreement of OI and OIII (±0.88 (95% confidence interval), ±1.305) was better than of OII (±2.21) in 4S and 5S (±0.99, ±2.00 and ±0.91; OI, OII and OIII, respectively) while it was relatively similar in DA (±18, ±17 and ±17). Inter-observer agreement was better in DA (OI–OII: ±13, OI–OII: ±19, OII–OIII: ±26) than in 4S (OI–OII: ±1.76; OI–OIII: ±1.29 and OII–OIII: ±1.31) or 5S (OI–OII: ±1.49; OI–OIII: ±0.91 and OII–OIII: ±1.20).ConclusionIntra-observer and inter-observer agreement was better in computerized grading followed by the subjective five-grade scale and four-grade scale.     

Evaluation of Chemical Properties of Mistletoe Leaves from Three Different Trees (Avocado,African Oil Bean and Kola)

A comparative evaluation of the chemical composition of mistletoe leaves (Viscum album) growing on three different trees: avocado pear (Persea Americana), African oil bean (Pentaclethra macrophylla) and kola (Kola nitida) was undertaken. Fresh mistletoe leaves were obtained from the three different trees and thoroughly washed with water after which they were dried at room temperature (28 ± 1 °C) for 18 days during the dry season (December). After, the dried leaves were shredded and packaged. The samples were then subjected to phyto-chemical, vitamin and mineral analyses using standard methods of analyses. Anthocyanins ranged between 0.3.4 ± 0.003 and 0.37 ± 0.181 mg/g, Tannin, 2.09 ± 1.141 and 3.24 ± 0.003 mg/g, Chlorophyll a, 0.38 ± 0.004 and 0.39 ± 0.018 mg/g, Chlorophyll b 0.52 ± 0.120 and 0.60 ± 0.001 mg/g. Vitamin B1 ranged between 0.85 ± 0.038 and 0.94 ± 0.001 mg/g, Vitamin B2, 0.55 ± 0.007 and 0.61 ± 0.003 mg/g, Vitamin C, 0.77 ± 0.003 and 1.98 ± 0.003 mg/g, Folate 0.53 ± 0.004 and 0.58 ± 0.004 mg/g, Magnesium ranged between 0.21 ± 0.002 and 0.92 ± 0.003 mg/g, Calcium 2.14 ± 0.004 and 2.26 ± 0.001 mg/g, Sodium 0.01 ± 0.000. Iron, 1.24 ± 0.005 and 1.42 ± 0.006 mg/g. Sample obtained from oil bean tree showed lower and differed significantly (p < 0.05) in Anthocyanin and Chlorophyll b with samples obtained from avocado and kola trees. The sample obtained from avocado tree showed higher Tannin content compared with samples obtained from oil bean and kola trees (P ≤ 0.05). There were significant differences (P < 0.05) between the samples in all the vitamins. The minerals showed significant differences in the samples (P < 0.05) except in sodium content which was very low in all the samples. Mistletoe leaves are shown to have a rich chemical composition and could thus serve as a source of these phyto-chemicals, vitamins and minerals.     

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.     

Influence of reuterin-producing Lactobacillus reuteri coupled with glycerol on biochemical,physical and sensory properties of semi-hard ewe milk cheese

The biochemical, physical and sensory characteristics of ewe milk cheeses made with reuterin-producing Lactobacillus reuteri and glycerol (substrate for reuterin production) were assessed. Cheese made with lactococci starter (CTRL), cheese made with starter and L. reuteri (SLR), and cheese made with starter, L. reuteri and 30 mM glycerol (SLR-G) were manufactured. L. reuteri reached counts above 7 log cfu/g on day 1. Lactococci survival was enhanced in SLR cheese without affecting cheese pH, dry matter, proteolysis, concentration of most free amino acids (FAA), textural and most color parameters, or sensory characteristics. In situ production of reuterin by L. reuteri was only detected in SLR-G cheese, decreasing LAB counts although acidification remained unaffected. SLR-G cheese showed higher values of cell free aminopeptidase activity, overall proteolysis and FAA, particularly glutamic acid, than CTRL and SLR cheeses. The addition of L. reuteri-glycerol resulted in lower hardness and elasticity values in SLR-G cheese and influenced its L*, a* and b* color parameters. However, these changes, which were detected by instrumental analysis, did not affect the sensory scores for texture and color quality of SLR-G cheese, and it received the highest scores for taste quality. Our results suggest that L. reuteri-glycerol may provide a suitable system to release the antimicrobial reuterin in cheese without affecting negatively its sensory characteristics.     

Binding of retinyl acetate to whey proteins or phosphocasein micelles: Impact of pressure-processing on protein structural changes and ligand embedding

A whey protein isolate (WPI) and native phosphocaseins (PC) at pH 6.5–6.6 were processed with retinyl acetate (RAC) using pressure-assisted technological tools to improve RAC embedding through processing-induced protein structural changes. To this end, protein-RAC dispersions were submitted to ultra-high pressure homogenisation (UHPH) at 300 MPa and an initial fluid temperature (T_in) of 14 °C or 24 °C, or isostatic high-pressure at 300 MPa and 14 °C or 34 °C for 15 min. A short-time thermal treatment (STTT, 73 °C for 4 s) able to generate WPI aggregates was assessed for comparison. Processing effects were investigated in terms of protein particle sizes and molecular weights (M_w). M_w calculated using protein size determination obtained from light scattering measurements were in agreement with the known values. The amounts of RAC retained in WPI particles (unfolded and/or aggregated proteins) or in PC assemblies were quantitated after protein precipitation by ammonium sulphate. A 2.3–3.7 nmol RAC was carried per mg of pressure-denatured whey proteins, significantly less than after STTT (6.3 nmol RAC per mg of heat-denatured whey proteins) indicating that RAC embedding varied according to the technological tool, pressure or temperature. A 3.8–5.4 nmol RAC was carried per mg of PC assemblies through pressure-induced dissociation/reassociation of PC micelles. Combined pressure and mild temperature increased RAC embedding in PC assemblies.     

Moisture diffusivity and shrinkage of broad beans during bulk drying in an inert medium fluidized bed dryer assisted by dielectric heating

Drying behavior of broad beans (Vicia faba) was studied in a pilot scaled fluidized bed dryer with inert particles assisted by dielectric heating. The effective diffusion coefficient of moisture transfer was determined by Fickian method at four different air drying temperatures of 35, 45, 55 and 65 °C. Correlations for moisture diffusivity as a function of moisture content and temperature of the drying medium were developed. The values of moisture diffusivity were obtained within the range of 1.27 × 10^?9–6.48 × 10^?9 m²/s and the activation energies for FBD and FBD + DE were found to be 27.71 and 17.10 kJ/mol, respectively. The shrinkage behavior of the broad beans was also investigated by considering the volume ratio of (V/V_O) to be function of moisture content alone and fitting a polynomial of the third order. The dielectric heating power was also found to be effective on the rate of drying.     

The influence of multi stage alginate coating on survivability of potential probiotic bacteria in simulated gastric and intestinal juice

The probiotics, Lactobacillus acidophilus PTCC1643 and Lactobacillus rhamnosus PTCC1637, were encapsulated into uncoated calcium alginate beads and the same beads were coated with one or two layers of sodium alginate with the objective of enhancing survival during exposure to the adverse conditions of the gastro-intestinal tract. The survivability of the strains, was expressed as the destructive value (decimal reduction time). Particle size distribution was measured using laser diffraction technique. The thickness of the alginate beads increased with the addition of coating layers. No differences were detectable in the bead appearance by scanning electron microscopy (SEM). The alginate coat prevented acid-induced reduction of the strains in simulated gastric juice (pH 1.5, 2 h), resulting in significantly (P < 0.05) higher numbers of survivors. After incubation in simulated gastric (60 min) and intestinal juices (pH 7.25, 2 h), number of surviving cells were 6.5 log cfu mL^?1 for L. acidophilus and 7.6 log cfu mL^?1 for L. rhamnosus by double layer coated alginate microspheres, respectively, while 2.3 and 2.0 log cfu mL^?1 were obtained for free cells, respectively.     

The increased viability of probiotic Lactobacillus salivarius NRRL B-30514 encapsulated in emulsions with multiple lipid-protein-pectin layers

Probiotics have demonstrated various health benefits but have poor stability to sustain food processing and storage conditions, as well as after ingestion. Biopolymer beads are commonly studied to encapsulate probiotic cells to improve their stability, but the millimeter-dimension of these beads may not meet the quality requirement of food products. The aim of this study was to enhance the viability of Lactobacillus salivarius NRRL B-30514 by encapsulation in emulsion droplets with multiple lipid-protein-pectin layers. Spray-dried L. salivarius was suspended in melted anhydrous milk fat that was then emulsified in a neutral aqueous phase with whey protein isolate or sodium caseinate to prepare primary solid/oil/water (S/O/W) emulsions. Subsequently, pectin was electrostatically deposited onto the droplet surface at pH 3.0 to form secondary emulsions. The encapsulation efficiency was up to 90%. After 20-day storage at 4 °C, the viable cell counts of bacteria in secondary emulsions at pH 3.0 and primary emulsions at 7.0 were 3 log higher than the respective free cell controls. After heating at 63 °C for 30 min, free L. salivarius was inactivated to be undetectable, while about 2.0 log CFU/mL was observed for primary (at pH 7.0) and secondary (at pH 3.0) emulsion treatments. Additionally, a 5 log-CFU/g-powder reduction was observed after spray drying free L. salivarius, while a 2 log CFU/g reduction was observed for emulsion treatments with capsules smaller than 20 μm. Furthermore, cross-linking the secondary emulsion with calcium enhanced the viability of L. salivarius after the simulated gastric and intestinal digestions. Therefore, the studied S/O/W emulsion systems may be used to improve the viability of probiotics during processing, storage, and gastrointestinal digestion.     

Three dimensional temporal and spatial distribution of adult Oryzaephilus surinamensis and Sitophilus oryzae in stored wheat under different temperatures,moisture contents,and adult densities

Three dimensional temporal and spatial distributions of adult Oryzaephilus surinamensis at densities of 0.1, 1.0, and 5.0 adults/kg wheat (referred to as A/kg) and adult Sitophilus oryzae at densities of 1.0, 5.0, and 10.0 A/kg were determined in bins filled with 1.5 t wheat having 11.0 ± 0.8, 13.0 ± 0.6, or 15.0 ± 0.5% moisture content at 20 ± 1, 25 ± 1 or 30 ± 1 °C. At each of the five sampled locations, wheat was separated into three 15 kg vertical layers and the number of adults in each layer was counted.Less than 30% of adult O. surinamensis were recovered in the top layer, while more than 80% of adult S. oryzae were recovered in the top layer. Adults of O. surinamensis preferred the center locations in each layer and adults of S. oryzae preferred the top layer. Densities of both species at adjacent locations in the horizontal direction were autocorrelated with each other. The temporal continuous property might not exist for the adults of O. surinamensis but exists for the adults of S. oryzae. Even though both species had aggregated and clumped distribution at any temperature, moisture content and adult density, adults of O. surinamensis had a more homogeneous distribution than S. oryzae. These characterized patterns of distribution of adult insects could be used to effectively estimate their density inside stored grain-bins.