Milk fat contains a variety of nutritive and health-promoting compounds that guard against some disease. In the current system of global competition, when the quality of milk and milk products is not an option but rat...Milk fat contains a variety of nutritive and health-promoting compounds that guard against some disease. In the current system of global competition, when the quality of milk and milk products is not an option but rather a requirement, therefore, determining the purity of milk fat is critical. This study aims to validate analytical methods for detecting palm oil in a mixture of milk fat and palm oil. Methods of this study was involved detection of non-milk fat in fat blinders by determining the saponification value, iodine number, refractive index, butyro refractometer reading, Gas chromatography, Reverse Phase High-performance liquid chromatography, and Fourier transforms Infrared. The results of this study revealed that the saponification value, Iodine number, refractive index, and Butyro Reading could be used to detect the addition of palm oil by a level of 10% - 20% or more to the milk. The level of some fatty acids in the milk as determined by GC, such as myristic acid (C14:0), palmitic acid (C16:0), and stearic acid (C18:0), is correlated well with the level of adding palm oil to milk fat. The determination of cholesterol and β-sito-sterol content by RP-HPLC could be used for the detection of the addition of palm oil to milk fat. The spectrum behavior produced by FTIR spectroscopy in this adulterated sample is almost the same, so this technique could not be used to detect the palm oil in milk fat.展开更多
This study investigated the effect of using different combinations of commercial starter culture and lactobacilli strains on the antioxidant properties of fermented camel milk for 14 days. The bacterial strains includ...This study investigated the effect of using different combinations of commercial starter culture and lactobacilli strains on the antioxidant properties of fermented camel milk for 14 days. The bacterial strains included Lb. casei subsp. casei B-1922, Lb. paracasei subsp. paracasei B-4560, Lb. rhamnosus B-442 and Lb. rhamnosus B-1445. The antioxidant activity of fermented milk was estimated using DPPH radical scavenging activity, ferrous ion chelating activity (FCA) and ferric reducing power assays. The total phenolic content (TPC), titratable acidity, proteolysis degree and sensory acceptability of samples were also evaluated. The results showed that all the studied parameters were affected by both the type of starter culture and storage. Samples containing the commercial starter and Lb. rhamnosus B-1445 had the highest DPPH radical scavenging activity and TPC throughout storage. Fermented milks prepared using the commercial starter and Lb. rhamnosus B-442 or Lb. paracasei retained their high FCA and reducing power throughout storage compared to the other samples. Fermented milk containing the commercial starter and Lb. casei showed the lowest antioxidant activity. The DPPH scavenging activity for all fermented milks decreased sharply during storage, while the change in FCA, reducing power and TPC differed among the samples during storage. The highest acidity was observed in the samples containing the commercial starter and Lb. paracasei, while fermented milk prepared using commercial starter and Lb. rhamnosus B-1445 had the lowest acidity. Samples containing the commercial starter and Lb. casei had the greatest proteolysis during the first week of storage, while samples containing the commercial starter and Lb. rhamnosus B-1445 had the highest proteolysis on day 14. Fermented milks with commercial starter and Lb. rhamnosus B-1445 or Lb. paracasei were the most acceptable products, while samples containing the commercial starter and Lb. casei were less acceptable.展开更多
文摘Milk fat contains a variety of nutritive and health-promoting compounds that guard against some disease. In the current system of global competition, when the quality of milk and milk products is not an option but rather a requirement, therefore, determining the purity of milk fat is critical. This study aims to validate analytical methods for detecting palm oil in a mixture of milk fat and palm oil. Methods of this study was involved detection of non-milk fat in fat blinders by determining the saponification value, iodine number, refractive index, butyro refractometer reading, Gas chromatography, Reverse Phase High-performance liquid chromatography, and Fourier transforms Infrared. The results of this study revealed that the saponification value, Iodine number, refractive index, and Butyro Reading could be used to detect the addition of palm oil by a level of 10% - 20% or more to the milk. The level of some fatty acids in the milk as determined by GC, such as myristic acid (C14:0), palmitic acid (C16:0), and stearic acid (C18:0), is correlated well with the level of adding palm oil to milk fat. The determination of cholesterol and β-sito-sterol content by RP-HPLC could be used for the detection of the addition of palm oil to milk fat. The spectrum behavior produced by FTIR spectroscopy in this adulterated sample is almost the same, so this technique could not be used to detect the palm oil in milk fat.
文摘This study investigated the effect of using different combinations of commercial starter culture and lactobacilli strains on the antioxidant properties of fermented camel milk for 14 days. The bacterial strains included Lb. casei subsp. casei B-1922, Lb. paracasei subsp. paracasei B-4560, Lb. rhamnosus B-442 and Lb. rhamnosus B-1445. The antioxidant activity of fermented milk was estimated using DPPH radical scavenging activity, ferrous ion chelating activity (FCA) and ferric reducing power assays. The total phenolic content (TPC), titratable acidity, proteolysis degree and sensory acceptability of samples were also evaluated. The results showed that all the studied parameters were affected by both the type of starter culture and storage. Samples containing the commercial starter and Lb. rhamnosus B-1445 had the highest DPPH radical scavenging activity and TPC throughout storage. Fermented milks prepared using the commercial starter and Lb. rhamnosus B-442 or Lb. paracasei retained their high FCA and reducing power throughout storage compared to the other samples. Fermented milk containing the commercial starter and Lb. casei showed the lowest antioxidant activity. The DPPH scavenging activity for all fermented milks decreased sharply during storage, while the change in FCA, reducing power and TPC differed among the samples during storage. The highest acidity was observed in the samples containing the commercial starter and Lb. paracasei, while fermented milk prepared using commercial starter and Lb. rhamnosus B-1445 had the lowest acidity. Samples containing the commercial starter and Lb. casei had the greatest proteolysis during the first week of storage, while samples containing the commercial starter and Lb. rhamnosus B-1445 had the highest proteolysis on day 14. Fermented milks with commercial starter and Lb. rhamnosus B-1445 or Lb. paracasei were the most acceptable products, while samples containing the commercial starter and Lb. casei were less acceptable.
