EFFECT OF TEMPERATURE AND STORAGE PERIOD ON PROPERTIES OF SUDANESE WHITE CHEESE

Abstract

This investigation was carried out to evaluate the effect of temperature and storage period on properties of Sudanese white cheese. Cheese was made from cow’s milk using the traditional method, 500 gm of cheese were packaged in each 24 plastic container , twelve packages were stored at room temperature (36+3°C) and the other half was stored at refrigerator. Cheese samples were analyzed at zero time, then after 30, 60,75 and 90 days of storage. Cheese was analyzed for moisture, ash, fat, protein, acidity and pH. Microbial analysis for total bacterial viable count, Coliform, E.coli, staphylococcus aureus, yeasts and moulds count were carried out, and organoleptically evaluted for color, taste flavor ,texture and over all acceptability. Moisture content of white cheese at zero time was 54.68% then increased to 57.06% at day 30 , and dropped to 55.60% at day 60 and increased 56.57% at day 75 and decreased to 55.27% at the end of storage period at room temperature , on the other hand, the cheese stored at cold storage, the moisture content increased to 55.70% at day 30 and decreased at day 60, 75 and 90 recorded 54 .53 % , 53.10% and 53.90% respectively. Ash content at zero time was 3.23% then decreased to 3.10% at day 30 and increased to 3.30% and 3.70% at day 60 and 75, then decreased to 3.03% at day 90 in cheese stored at room temperature , at cold storage it increased at day 30 ,60 and 75 and dropped rapidly to 3.20% at day 90. The fat content was 23% at zero time and dropped rapidly to 21% at day 30 and increased to 26.67 % at day 90 at room temperature, however it increased to 24% at 30 days then decreased to 21% at day 90 of cold storage The protein content at zero time 15.45% decreased to 12.28% at day 30 and 13% at day 90 at room temperature , at cold storage it decreased to 14.06% at day 30 then recorded at day 60 , 75 and 90 as 14.50% , 14.70% and 14.63% respectively. The pH value decreased from 6.2 to 3.73 at room temperature storage ,and decreased from 6.2 to 5.63 at cold storage but the acidity increased from 0.5 to 1.21 at room temperature and from 0.5 to 0.95 at cold storage 4 Total bacterial count increased gradually from 3.37×10 to 6 7.0×10 at day 60 and decreased to 5.47×10 at day 90 at room 4 temperature , at cold storage increased gradually to 8.73 ×10 at day 60 5 day and to 5.53 ×10 at day 90 of storage. Coliform bacteria observed at 30 day 20 MPN/gm and increased to 190MPN/gm at day 90 of storage at room temperature, E.coli bacteria observed at day 30 as 56MPN/gm and decreased to 26 MPN/gm at day 90 of storage at room temperature . S.aureus was observed at day 75 and 90 5.7×102 and 4.5×103 respectively at room temperature . 5 Yeast count increased from 1.47 ×102 to 7.07×10 at day 90 at room temperature , at cold stored increased from 1.47 ×102 to 8.27 ×103 at day 90 of storage. No mould was observed at cold storage , but observed at day 75 and 90 as 6.9×102 and 4.6×103 respectively at room temperature . Panelist recorded high mean values (color , flavor , taste , texture , over all acceptability) in cheese stored at cold storage than cheese stored at room temperature , and highest values were recorded after 90 day of cold storage.