The aim of this study was to evaluate the effect of a synbiotic containing Lactobacillus acidophilus ATCC 4962, fructooligosaccharide, inulin and mannitol on plasma lipid profiles and erythrocyte membrane properties in hypercholesterolaemic pigs on high- and low-fat diets. Twenty-four white male Landrace pigs were randomly allocated to four treatment groups for 8 weeks (n 6). Treatment factors were the supplementation of synbiotic (with and without) and dietary fat (5 and 15 %). The supplementation of synbiotic reduced plasma total cholesterol (P = 0.001), TAG (P = 0.002) and LDL-cholesterol (P = 0.045) for both dietary fats. A higher concentration of esterified-cholesterol in HDL of pigs supplemented with synbiotic than the control regardless of dietary fat (P = 0.036) indicated that cholesterol was reduced in the form of cholesteryl esters. Reduced concentration of cholesteryl esters (P < 0.001) and increased concentration of TAG (P = 0.042) in LDL of pigs on synbiotic suggested that LDL-cholesterol was reduced via the hydrolysis of smaller and denser LDL particles. The erythrocytes of pigs without any synbiotic showed more prevalence of spur cells than those given the synbiotic, as supported by the higher cholesterol: phospholipid ratio in erythrocytes (P = 0.001). Also, membrane fluidity and rigidity were improved as supported by the decreased fluorescence anisotropies in the Hb-free erythrocyte membrane of pigs given synbiotic (P < 0.001). The administration of the synbiotic reduced plasma TAG, total cholesterol and LDL-cholesterol in hypercholesterolaemic pigs, possibly in the form of cholesteryl esters, via the interrelated pathways of lipid transporters (VLDL, LDL and HDL). The synbiotic also reduced deformation of erythrocytes via improved membrane fluidity and permeability.
Production of probiotic food supplements that are shelf-stable at room temperature has been developed for consumer's convenience, but information on the stability in acid and bile environment is still scarce. Viability and acid and bile tolerance of microencapsulated Bifidobacterium spp. and Lactobacillus acidophilus and 4 commercial probiotic supplements were evaluated. Bifidobacterium and L. acidophilus were encapsulated with casein-based emulsion using spray drying. Water activity (aw ) of the microspheres containing Bifidobacterium or L. acidophilus (SD GM product) was adjusted to 0.07 followed by storage at 25 °C for 10 wk. Encapsulated Bifidobacterium spp. and Lactobacillus acidophilus and 4 commercial probiotic supplement products (AL, GH, RE, and BM) were tested. Since commercial probiotic products contained mixed bacteria, selective media MRS-LP (containing L-cysteine and Na-propionate) and MRS-clindamycin agar were used to grow Bifidobacterium spp. or L. acidophilus, respectively, and to inhibit the growth of other strains. The results showed that aw had a strong negative correlation with the viability of dehydrated probiotics of the 6 products. Viable counts of Bifidobacterium spp. and L. acidophilus of SD GM, AL, and GH were between 8.3 and 9.2 log CFU/g, whereas that of BM and RE were between 6.7 and 7.3 log CFU/g. Bifidobacterium in SD GM, in AL, and in GH products and L. acidophilus in SD GM, in AL, and in BM products demonstrated high tolerance to acid. Most of dehydrated probiotic bacteria were able to survive in bile environment except L. acidophilus in RE product. Exposure to gastric juice influenced bacterial survivability in subsequent bile environment.
The aims of this study were to evaluate the effect of types of protein-based microcapsules and storage at various ambient temperatures on the survival of Lactobacillus acidophilus during exposure to simulated gastrointestinal tract and on the change in thermo-tolerance during heating treatment. The encapsulating materials were prepared using emulsions of protein (sodium caseinate, soy protein isolate, or pea protein), vegetable oil, and glucose, with maltodextrin was used as a wall material. The formulations were heated at 90 °C for 30 min to develop Maillard substances prior to being incorporated with L. acidophilus. The mixtures were then spray dried. The microspheres were stored at 25, 30, and 35 °C for 8 wk and examined every 4 wk. The addition of proteins as encapsulating materials demonstrated a significant protective effect (P < 0.05) as compared to the control sample. Sodium caseinate and soy protein isolate appeared more effective than pea protein in protecting the bacteria after spray drying and during the storage at different room temperatures. Storage at 35 °C resulted in a significant decrease in survival at end of storage period regardless the type of encapsulating materials. The addition of protein-based materials also enhanced the survival of L. acidophilus during exposure to simulated gastrointestinal condition as compared to the control. After spray drying and after 0th wk storage, casein, soy protein isolate, and pea protein-based formulations protected the bacteria during heat treatment. In fact, a significant decrease in thermal tolerance was inevitable after 2 wk of storage at 25 °C.