EFFECT OF STORAGE TEMPERATURE, QUALITY OF CREAM AND HANDING PRACTICES ON SHELF LIFE OF BUTTER

Abstract

It has been complained by regular customers and retailers that large proportions of salted butter samples get deteriorated due to rancidity and microbial growth rather before its expected shelf life under domestic refrigeration conditions, which in turn greater extent of returns becoming inevitable and continuously faces to the problem profit loss. Therefore the objective of this research was to determine the root cause that leads to deprive the storage stability of “Highland” salted-butter in order to the shelf life under domestic refrigeration conditions. First approach was to study the butter manufacturing process. Foremost, principle raw materials, equipments and machineries that are used in butter manufacturing were identified.Thereafter actual processing flow diagram along with workers traffic pattern was out lined to identify the most probable steps that may lead to cross contaminations. The quality of incoming cream is very important for shelf life of butter. Quality of incoming cream was evaluated using two quality parameters. The physico-chemical quality was evaluated by analyzing the titrable acidity, where as the microbiological quality was evaluated by performing total plate count. Another important factor is storage temperature of butter. It was evaluated using acidity level at two temperatures (10°C and -10°C). Free fatty acid level was identified using titration method, and continued for ten weeks. Finally, the results were statistically analyzed. Handling practices are very important in butter manufacturing. Handling practices was observed and identify bad manufacturing practices. Acidity test (P value 0.009) indicates that there is a day to day variation in percentage acidity and thus, assuring the uniformity of end product is somewhat questionable. However, average acidity of the each cream sample is far less compared to the minimum allowable acidity i.e.,0.14%. The maximum CFU/ml shall be 50 for a cream if it is utilized for butter manufacturing. The two cream samples conform to the specifications where as one cream sample is somewhat inferior in microbiological quality. The average shelf-life of butter was determined using regression equation at these two temperatures. Sample of butter stored in butter cold room had a shelf-life of 46 weeks. On other hand, samples of butter stored in normal refrigerated condition had a shelf-life of 24 weeks. According to these results, storage temperature directly affects to shelf life of butter.