Effect of Varied Levels of Cassava Powder Manihot esculenta on Physicochemical Characteristics and Quality of White Soft Cheese from Cow's Milk During Storage

Abstract

This study was carried out at the laboratory of Dairy Science and Technology Department, College of Animal Production Science and Technology at Sudan University of Science and Technology during the period from January to July 2013 to determine the effect of different levels of cassava powder on the physicochemical characteristics, microbiological quality, yield and sensory characteristics of the Sudanese white soft cheese during storage. One hundred and twenty liters (120 liters) of fresh cow's full cream milk was used for the production of a Sudanese white soft cheese with different levels of cassava powder (Control, 0.5, 0.75 and 1 % respectively). The milk was pasteurized at 72oC for 1 minute and then manufactured into a Sudanese white soft cheese and stored at room temperature for 90 days and examined for the physicochemical, microbiological and organoleptic quality at day 0, 30, 60 and 90 intervals. The results indicated that total solids contents decreased significantly (P<0.05) with increasing levels of cassava powder, while fat, crude protein, acidity and volatile fatty acid increased significantly (P<0.05) with the levels of cassava powder. There were no significant effect (P>0.05) of cassava powder on pH and ash contents of the Sudanese white soft cheese. The pH decreased with the levels of cassava powder, while ash increased. Vitamin C, calcium and phosphorus increased significantly (P<0.05) with the levels of cassava, while there were no significance effect on sodium and potassium. There were significance effect (P<0.05) by the levels of cassava on total bacteria count, lactobacilli , streptococci , yeasts and moulds and Staphylococcus aureus , while there was no significance effect on coliforms. The total bacteria count and coliforms increased with the levels of cassava, while lactobacilli, streptococci, yeasts and moulds and Staphylococcus aureus were decreased. The yield of the Sudanese white soft cheese was affected by the addition of different levels of cassava powder to milk. The yield increased with the addition of cassava powder. The yield of the cheese made from milk with 1 % cassava was the highest (17.78 %) while the lowest one was recorded by the cheese made from milk without cassava (15.93 %). The organoleptic quality of cheese revealed that there were significance effect (P<0.05) of cassava powder on color, texture and saltiness, while there were no significance effect on flavor, taste and over all acceptability. The results also indicated that there were significant effect (P<0.05) of the storage period on total solids , fat , protein , titratable acidity, pH and volatile fatty acids, while there was no significant variations on the ash content. Total solids, titratable acidity, volatile fatty acid increased with the storage period, while fat, crude protein and pH decreased. Vitamin C, calcium, phosphorus sodium and potassium decreased significantly (P<0.05) with storage period. The total bacteria count increased significantly (P<0.05) with the storage period up to day 60 and then decreased, while lactobacilli, streptococci, coliforms and Staphylococcus aureus were significantly (P<0.05) decreased with the storage period from the beginning up to the end. Yeasts and moulds significantly (P<0.05) increased with the storage period from day 0 up to day 90. All the sensory characteristics of the white cheese were significantly (P<0.05) affected by the storage period. Results showed that the best values for color, flavor, texture, taste and over all acceptability were obtained at the first day (day zero) of the storage period, while the highest value for the saltiness was recorded at the day 30. The color of the cheese decreased from the day zero up to the end of the storage (day 90). The flavor scores reduced from the day zero up to day 60 and then increased again at the day 90 of the storage. The lowest value for texture and taste were recorded at the day 30 of the storage. The saltiness increased at the day 30 and then decreased again up to the end of the storage period. The over all acceptability reduced by the storage period from day zero up to the day 60 and then increased again at the day 90. The best over all acceptability was recorded at day zero, while the lowest one was at the day 30.