This study was conducted to evaluate the effects of grass and flaxseed oil on weight gain, fecal pH, microflora and acid resistance of fecal E. coli. in Friesian-Holsteins. Fifteen Holsteins were fed either conventional diet (C, n=5), grass (40%) and concentrate supplemented with flaxseed oil (60%) (T1, n=5) or grass only (T2, n=5) for 141 days, and T1 and T2 groups were grazed on pasture except feeding time. Grabbing fecal samples and measuring body weight were carried out at test day 1, 60, 120, 141. To evaluate acid sensitivity of fecal E. coli, feces were incubated in pH 2.0 anaerobic solution during 1 h at room temperature and measured survival rate. In terms of diets, C group had the highest n-6:n-3 ratio with 21.93, followed by T1 group (0.92) and T2 group (0.51). C and T1 group had higher final weight, total gain weight and average daily gain than T2 animals (p<0.05). The fecal pH of C group was maintained much lower than T1 and T2 group since day 120 (p<0.05). Total anaerobe in feces of C group were higher than the other groups since day 120 (p<0.05), but coliform bacteria were not significantly different among groups. Yeast and mold in feces of C group were significantly higher than the other groups from day 60 to day 141 (p<0.05), which is considered to be relevant to yeast in the diets. After feces were incubated at strong acid, more fecal E. coli of C group (34.09%) survived than those of T1 group (3.79%) and T2 group (1.02%) (p<0.05). From those results, it was considered that feeding grass and flaxseed oil to Holsteins enables to change fecal microflora, increase acid sensitivity of fecal E. coli and contribute to stay healthy for animals. It would be necessary to develop various grass feed diets and their applications for producing healthy and high quality meat products.

This study was conducted to evaluate the effect on quality characteristics of grass-fed cow’s milk (GM) and conventional feed-fed cow’s milk (CM) with various conditions of non-thermal high-pressure processing (HPP) sterilization process. The sterilized GM and CM stored at 5℃ and 10℃ for 14 days and their quality characteristics during storage was evaluated. The pH and titratable acidity changes of HPP sterilized milk were maintained acceptable level 6.7-6.8, 0.14-0.16%, respectively. HPP sterilization was efficient in the reduction of total bacterial population to decrease the level of 4-7 Log CFU/ml compare to those of unsterilized control milk, and coliform bacteria was not detected in the HPP sterilized milk. Non-thermal HPP sterilization processing was not affected milk fatty acid composition compare to those of low temperature long time process (LTLT) sterilized milk. GM has lower ratio of n-3:n-6 unsaturated fatty acid level than those of CM. In the sensory evaluation of GM and commercial milk products, overall consumer acceptance of HPP sterilized GM was higher than CM and LTLT commercial product. In conclusion, the effects of HPP was comparable with conventional LTLT sterilization process to control undesirable microorganism in the milk products with minumal nutritional and chemical changes.

Effects of high pressure processing on physicochemical and microorganisms properties in birch sap were investigated using variable high pressure processing conditions. The viable cell counts of untreated birch sap was 4.0 log CFU, whereas high pressure processed sap were not detected. In birch sap was treated with 450 to 550 MPa, microorganisms were not detected during storage period, and physicochemical properties as well as color were slightly changed. The more processing time and pressure, its quality variations were more stable and then its optimum processing condition was determined with 120 sec at 550 MPa. The microorganisms and physicochemical properties of treated birch sap were investigated during storage at 5℃ and 10℃ for 45 and 28 days. Changes of physicochemical properties of treated birch sap were smaller than those of the untreated, but viable cell count were not detected during storage period. As for pH, °Brix, and turbidity result of birch sap, quality shelf life of control and treatment were 4 and 24 days, respectively. Especially, ΔE value of instrumental color was untreated birch sap 4 days similar with the high pressure processed it for 28 days. These results indicated that the high pressure processing can be used as an effective method to improve the shelf life of birch sap.