Mixed Biopolymer Systems Based on Bovine and Caprine Caseins, Yeast ß-Glucan, and Maltodextrin for Microencapsulating Lutein Dispersed in Emulsified Lipid Carriers.

Lutein is an important antioxidant that quenches free radicals. The stability of lutein and hence compatibility for food fortification is a big challenge to the food industry. Encapsulation can be designed to protect lutein from the adverse environment (air, heat, light, pH). In this study, we determined the impact of mixed biopolymer systems based on bovine and caprine caseins, yeast ß-glucan, and maltodextrin as wall systems for microencapsulating lutein dispersed in emulsified lipid carriers by spray drying. The performance of these wall systems at oil/water interfaces is a key factor affecting the encapsulation of lutein. The highest encapsulation efficiency (97.7%) was achieved from the lutein microcapsules prepared with the mixed biopolymer system of caprine αs1-II casein, yeast ß-glucan, and maltodextrin. Casein type and storage time affected the stability of lutein. The stability of lutein was the highest (64.57%) in lutein microcapsules prepared with the mixed biopolymer system of caprine αs1-II casein, yeast ß-glucan, and maltodextrin, whereas lutein microcapsules prepared with the biopolymer system of bovine casein, yeast ß-glucan, and maltodextrin had the lowest (56.01%). The stability of lutein in the lutein microcapsules dramatically decreased during storage time. The antioxidant activity of lutein in the lutein microcapsules was closely associated with the lutein concentration.

Stability of Fucoxanthin in Pasteurized Skim and Whole Goat Milk.

Obesity has become a worldwide problem giving rise to several health issues. Fucoxanthin, a marine carotenoid with anti-obesity activity, has potential application as a biofunctional ingredient in human food. The objective of this study was to evaluate the thermal stability of fucoxanthin at pasteurization temperature and, subsequently, its storage stability in goat whole milk (WM) and skim milk (SM) at refrigeration temperature for four weeks. Additionally, the effect of supplementation of fucoxanthin on the composition of milk, pH, acidity, color, and lipid oxidation of WM and SM was evaluated during the four week storage period. Fresh goat WM and SM were supplemented with fucoxanthin at a concentration of 10.67 µg/mL (2.56 mg/240 mL of milk, one serving), pasteurized at 64 °C for 30 min and stored at 4 °C for four weeks. The quantification of fucoxanthin in WM and SM was performed every week using a HPLC method. Moreover, the effect of supplementation of fucoxanthin on the composition of WM and SM was evaluated by a LactiCheck milk analyzer, and the color was evaluated by reflectance using a HunterLab colorimeter. Lipid oxidation, as the 2-thiobarbituric acid-reactive substances (TBARS) at A532, was determined using a Spectramax Plus spectrophotometer during storage. Data were analyzed by a split-plot design using PROC MIXED of SAS. The recovery yields of fucoxanthin from the pasteurized WM and SM were 96.17 ± 1.5 % and 96.89 ± 1.5 %, respectively. Both milks exhibited high recovery yields of fucoxanthin. Fucoxanthin was stable in goat WM and SM during storage at 4 °C for four weeks. The addition of fucoxanthin, at the concentration reported to have an anti-obesity effect in humans, to pasteurized WM and SM did not affect the composition or the physicochemical properties of milks but influenced the color, especially increasing the yellowness in the samples. These results revealed that goat milk can be used as a suitable matrix for the supplementation of fucoxanthin as a biofunctional ingredient in human foods.

Interface Compositions as Determinants of Resveratrol Stability in Nanoemulsion Delivery Systems.

The incorporation of hydrophobic ingredients, such as resveratrol (a fat-soluble phytochemical), in nanoemulsions can increase the water solubility and stability of these hydrophobic ingredients. The nanodelivery of resveratrol can result in a marked improvement in the bioavailability of this health-promoting ingredient. The current study hypothesized that resveratrol can bind to caprine casein, which may result in the preservation of the biological properties of resveratrol. The fluorescence spectra provided proof of this complex formation by demonstrating that resveratrol binds to caprine casein in the vicinity of tryptophan amino acid residues. The caprine casein/resveratrol complex is stabilized by hydrophobic interactions and hydrogen bonds. Hence, to study the rate of resveratrol degradation during processing/storage, resveratrol losses were determined by reversed-phase high performance liquid chromatography (RP-HPLC) in nanoemulsions stabilized by bovine and caprine caseins individually and in combination with polysorbate-20. At 48 h oxidation, 88.33% and 89.08% was left of resveratrol in the nanoemulsions stabilized by caprine casein (αs1-I)/polysorbate-20 complex and caprine (αs1-II)/polysorbate-20 complex, while there was less resveratrol left in the nanoemulsions stabilized by bovine casein/polysorbate-20 complex, suggesting that oxygen degradation was involved. The findings of this study are crucial for the food industry since they imply the potential use of caprine casein/polysorbate-20 complex to preserve the biological properties of resveratrol.

Applicability of Screening Tests for Oxytetracycline in the Milk of Three Breeds of Goats.

Antibiotics are widely used in animal husbandry, and the presence of antibiotic residues in milk is a health hazard. The objectives of this study were to determine residual amounts of oxytetracycline in the milk of three breeds of goats using high-pressure liquid chromatography (HPLC) analysis and screening tests. It was also essential to explore the safe withdrawal period of oxytetracycline in lactating goats and examine the applicability of Charm ROSA and SNAP screening tests. The qualitative results of these tests were compared with the quantitative results of the HPLC method. Fifteen milking does, five each from the Alpine, LaMancha, and Nubian breeds, were selected from the herd at Prairie View A&M University. Milk samples containing antibiotic residues were deproteinized by HCl and acetonitrile, and then oxytetracycline was extracted from the supernatant. The residues of oxytetracycline in goat's milk up to 110 h after injection were qualitatively detected using the Charm ROSA test. Similarly, the SNAP test detected the antibiotic residues in milk up to 110 h after treatment. The HPLC results indicated that oxytetracycline residues in milk from Alpine goats were below the tolerance level (300 ng/ml) 82 h after drug treatment (72 h for LaManchas, 58 h for Nubians); however, the results of the screening tests would indicate longer withdrawal periods for milk from the breeds of goats studied, which would result in economic losses to goat's milk producers. The results of this study also indicated that oxytetracycline was not stable in raw goat's milk at refrigeration temperature or during pasteurization and that the concentrations decreased significantly. Commercial goat's milk is usually exposed to several hours of refrigeration and then to pasteurization. The results of this study indicated that, if oxytetracycline was present in raw goat's milk, the concentration would decrease significantly before it was marketed.

Short communication: Determination of withdrawal time for oxytetracycline in different types of goats for milk consumption.

Antibiotics are widely used in animal husbandry and the presence of antibiotics in milk is a health hazard. The objective of this study was to determine residual amounts of oxytetracycline in fresh, aged, and pasteurized milk of 3 breeds of goats using HPLC analysis. It was also essential to determine the safe withdrawal period of oxytetracycline in lactating goats. The quantitative results obtained using the HPLC system were compared with the tolerance limit of oxytetracycline in milk in the United States. Fifteen milking does, 5 Nubians, 5 Alpines, and 5 LaManchas were randomly selected from the milking herd at the International Goat Research Center at Prairie View A&M University. A simple sample preparation and isocratic HPLC method using ultraviolet detection was used for analysis of milk samples. The HPLC results indicated that the withdrawal period of oxytetracycline in treated Alpine does was 82h (7 milking), whereas for Nubian does the period was 58h (5 milking), and for LaManchas the period was 72h (6 milking) after drug administration. The overall withdrawal period for all the treated goats of 3 breeds was 72h. Although these results indicated that the depletion rate of this antibiotic was faster in goats than the reported data for cows, the 96-h withdrawal period that is currently used for lactating cows is still necessary for these 3 breeds of goats. Additionally, our results indicated that oxytetracycline is not stable in goat milk at refrigeration temperature or during pasteurization and will decrease significantly.

Lipid oxidation in algae oil-in-water emulsions stabilized by bovine and caprine caseins.

Caseins (alpha(s1)-, alpha(s2)-, and beta-casein) are phosphoproteins that are capable of binding transition metals and scavenging free radicals; this property makes them good candidates to be used as natural antioxidants in oil-in-water emulsions. Caprine casein exhibits variability in alpha(s1)-casein content generated by genetic polymorphism. This variability in composition could lead to altered antioxidant properties. Thus, the ability of two caprine caseins differing in alpha(s1)-casein content to inhibit lipid oxidation in algae oil-in-water emulsions at 5% oil was investigated and compared to bovine caseinate. All caseins inhibited the formation of lipid oxidation at pH 7.0 as determined by lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). However, caprine caseins were in general more effective inhibitors of lipid oxidation than the bovine caseins, which may be attributed to their altered casein amino acid content and/or metal binding capabilities. The combination of the carotenoids with bovine and caprine caseins was highly effective at repressing oxidation leading to the speculation that the caseins may inhibit the loss of the carotenoids and/or react with and enhance the carotenoid activity; again some differences between bovine and caprine caseins were observed with caprine caseins being slightly more effective in the presence of carotenoids.

Influence of bovine and caprine casein phosphopeptides differing in alphas1-casein content in determining the absorption of calcium from bovine and caprine calcium-fortified milks in rats.

Bovine and caprine milks have a similar overall gross composition, but vary considerably in the ratios of their casein components. These differences cause significant changes in the ability of caseins to bind and stabilize calcium (Ca). It might be expected that these in vitro variations, which are thought to be due to differences in casein phosphopeptides (CPP) content, could lead to in vivo differences in the digestion and absorption of Ca. To test this hypothesis three milks with different casein ratios [bovine (B), caprine high in alphas1-casein (CH) and caprine low in alphas1-casein (CL)] were compared with regard to Ca absorption and deposition in growing male rats. For comparison, each milk was Ca-fortified (BCa-milk, CHCa-milk, and CLCa-milk) and CPP, prepared by enzymatic hydrolysis from the respective caseins (extrinsic CPP), were added to both native and Ca-milks. The effects of added CPP (extrinsic) could then be compared with intrinsic CPP released from the gastrointestinal digestion of caseins. Total gastric Ca was sampled at 15, 30 and 60 min after ingestion. No differences were found among the native milks with or without CPP, but the Ca from all Ca-milks (regardless of casein type) appeared to clear the stomach more rapidly and this was enhanced by the extrinsic CPP. The total intestinal Ca was not different among the native milks+/-CPP, however, it rose more rapidly with Ca fortification, and was higher at 30 min for all CPP-Ca-milks. At 60 min the total intestinal Ca level fell for the CPP-Ca-milks while all others continued to rise. These observations suggest that the CPP in Ca-milks enhance gastric clearance and uptake from the intestine. Ca availability from BCa-milk, CHCa-milk, and CLCa-milk with and without CPP was estimated by both plasma and femur uptake of 45Ca. Ca availability was enhanced at 5 h in the plasma in each case by added CPP. In all cases CPP stimulated Ca availability in the femur, but the CL-CPP was higher (P<0.05) than that of either CH-CPP or B-CPP (extrinsic CPP). Based on the results of this study we can conclude that the addition of CPP will have beneficial effect on the absorption of Ca in growing rats from CaCO3 added to bovine and caprine milks.