Microbiological aspects of the traditional Travnik/Vlasic cheese manufactured in Bosnia and Herzegovina.

The microbiological aspects of traditional Travnik/Vlasic cheese was investigated. The cheese was made traditionally, from raw sheep milk at three small farms (A, B, C) on Mountain Vlasic. The microbiological quality of the cheese was examined during three stages of ripening (5, 30, 60 days) and followed during three seasons (3 years). Twenty-seven samples of cheese were collected and analyzed for the aerobic mesophilic count, yeasts and molds, coliforms and microorganisms from the group Staphylococcus spp. Average values determined for the number of investigated groups of microorganisms of all cheese samples throughout three different stages, seasons, and small farms were: aerobic mesophilic bacteria 8.03 log10 cfu·g-1, yeasts and molds 3.63 log10 cfu·g-1, coliforms 5.16 log10 cfu g-1, and microorganisms from the group Staphylococcus spp. 4.49 log10 cfu g-1. ANOVA showed that experimental factor ripening stage (days) had a significant effect on all testing parameters. Results obtained with this study indicate that hygiene during the production of traditional products must be increased in order to assure high quality of the final products.

Optimization of protein fractionation by skim milk microfiltration: Choice of ceramic membrane pore size and filtration temperature.

The objective of this study was to investigate how ceramic membrane pore size and filtration temperature influence the protein fractionation of skim milk by cross flow microfiltration (MF). Microfiltration was performed at a uniform transmembrane pressure with constant permeate flux to a volume concentration factor of 2.5. Three different membrane pore sizes, 0.05, 0.10, and 0.20µm, were used at a filtration temperature of 50°C. Furthermore, at pore size 0.10µm, 2 different filtration temperatures were investigated: 50 and 60°C. The transmission of proteins increased with increasing pore size, giving the permeate from MF with the 0.20-µm membrane a significantly higher concentration of native whey proteins compared with the permeates from the 0.05- and 0.10-µm membranes (0.50, 0.24, and 0.39%, respectively). Significant amounts of caseins permeated the 0.20-µm membrane (1.4%), giving a permeate with a whitish appearance and a casein distribution (αS2-CN: αS1-CN: κ-CN: ß-CN) similar to that of skim milk. The 0.05- and 0.10-µm membranes were able to retain all caseins (only negligible amounts were detected). A permeate free from casein is beneficial in the production of native whey protein concentrates and in applications where transparency is an important functional characteristic. Microfiltration of skim milk at 50°C with the 0.10-µm membrane resulted in a permeate containing significantly more native whey proteins than the permeate from MF at 60°C. The more rapid increase in transmembrane pressure and the significantly lower concentration of caseins in the retentate at 60°C indicated that a higher concentration of caseins deposited on the membrane, and consequently reduced the native whey protein transmission. Optimal protein fractionation of skim milk into a casein-rich retentate and a permeate with native whey proteins were obtained by 0.10-µm MF at 50°C.

Variation of terpenes in milk and cultured cream from Norwegian alpine rangeland-fed and in-door fed cows.

The terpene content of milk and cream made from milk obtained from cows fed indoors, and by early or late grazing, in alpine rangeland farms in Norway, were analysed for three consecutive years. The main terpenes identified and semi-quantified were the monoterpenes ß-pinene, α-pinene, α-thujene, camphene, sabinene, δ-3-carene, d-limonene, γ-terpinene, camphor, ß-citronellene, and the sesquiterpene ß-caryophyllene. The average total terpene content increased five times during the alpine rangeland feeding period. The terpenes α-thujene, sabinene, γ-terpinene and ß-citronellene were only detected in milk and cultured cream from the alpine rangeland feeding period and not in samples from the indoors feeding period. These four terpenes could be used, as indicators, to show that milk and cultured cream originate from the alpine rangeland feeding period. The terpenes did not influence the sensorial quality of the milk or the cultured cream.

The composition and functional properties of whey protein concentrates produced from buttermilk are comparable with those of whey protein concentrates produced from skimmed milk.

The demand for whey protein is increasing in the food industry. Traditionally, whey protein concentrates (WPC) and isolates are produced from cheese whey. At present, microfiltration (MF) enables the utilization of whey from skim milk (SM) through milk protein fractionation. This study demonstrates that buttermilk (BM) can be a potential source for the production of a WPC with a comparable composition and functional properties to a WPC obtained by MF of SM. Through the production of WPC powder and a casein- and phospholipid (PL)-rich fraction by the MF of BM, sweet BM may be used in a more optimal and economical way. Sweet cream BM from industrial churning was skimmed before MF with 0.2-µm ceramic membranes at 55 to 58°C. The fractionations of BM and SM were performed under the same conditions using the same process, and the whey protein fractions from BM and SM were concentrated by ultrafiltration and diafiltration. The ultrafiltration and diafiltration was performed at 50°C using pasteurized tap water and a membrane with a 20-kDa cut-off to retain as little lactose as possible in the final WPC powders. The ultrafiltrates were subsequently spray dried, and their functional properties and chemical compositions were compared. The amounts of whey protein and PL in the WPC powder from BM (BMWPC) were comparable to the amounts found in the WPC from SM (SMWPC); however, the composition of the PL classes differed. The BMWPC contained less total protein, casein, and lactose compared with SMWPC, as well as higher contents of fat and citric acid. No difference in protein solubility was observed at pH values of 4.6 and 7.0, and the overrun was the same for BMWPC and SMWPC; however, the BMWPC made less stable foam than SMWPC.

Microbiological hazard identification and exposure assessment of food prepared and served in rural households of Lungwena, Malawi.

The presence of food-borne pathogens, Escherichia coli 0157:H7, Staphylococcus aureus, Salmonella species, Campylobacter jejuni and non-pathogenic E. coli, in 132 home cooked food samples consisting of maize flour porridge (MFP), (n=41), fish (n=37), vegetables (n=28), beans (n=13) and "Others" (n=13), collected from 6 villages in Lungwena, Malawi was investigated. It was found that 35% of the food samples were contaminated with one or more pathogens; with 48%, 8%, 61% and 23% of the food samples being found to harbour E. coli, pathogenic E. coli 0157: H7, S aureus and Salmonella species, respectively. C. jejuni was not detected in any food sample. Using a 95% level of significance, pathogen concentration among food categories demonstrated a statistical difference (p=0.001). Distribution of pathogens among villages was also found to be significant (p=0.03). MFP was the most contaminated food. Practices that promote the spread of the pathogens in the rural household kitchens were investigated. Food was thought to be contaminated as a result of poor food handling, preparation and storage practices.