PHYSICO-CHEMICAL CHANGES AFFECTING THE NUTRITIONAL AND TECHONOLOGICAL VALUE OF WHEAT GRAINS STORED IN DIFFERENT TYPE OF CONTAINERS

Abstract

Wheat is staple food for most of the world population. However, a lot of grain is damaged and/or wasted during storage particularly in developing countries where a huge quantity of grain is stored as household level. Therefore, proper storage conditions for wheat grains can bring about considerable improvement in national economy through control in losses in both the quantity as well as quality. Information on biochemical changes in wheat because of storage in different household containers and their effects on products are either scanty or outdated. Keeping in view the facts a research was planned to investigate the changes in quality of wheat grains during storage in different containers commonly used at household level in Pakistan i.e. earthen pots, tin containers, cotton bags, jute bags and polypropylene bags. Newly harvested grains of three commonly growing. wheat varieties i.e. Chakwal-97, Margalla-99 and Wafaq-2001 after fumigation were stored for 12 months in two consecutive years i.e. 2003-04 and 2004-05 in these containers at existing environmental conditions. Samples were analyzed before storage and after every 4 months for different quality parameters i.e. moisture content, test weight, flour yield, particle size index, flour color, ash, protein, fat, crude fiber, gluten, falling number, fat acidity, water absorption, dough stability, farinograph quality number, total plate count, fungal colony and chapatti quality. Results of these quality parameters were statistically analyzed. Varietals contribution during storage was significant in most of the quality parameters. Chakwal-97 showed higher PSI, ash, protein, gluten, dough stability, FQN, Chapatti quality score and lower TPC. Margalla-99 is suitable for maintaining low values for moisture, highest flour yield, crude fat, crude fiber and xixwater absorption capacity along with higher chapatti quality score. As for as Wafaq-2001 is concerned it showed its ability to have lower moisture content, higher test weight, PSI, crude fat, crude fiber during storage in different containers and duration. The quality parameters considered in this study were also affected by the storage time. At initial stage lowest moisture, higher test weight and flour yield, lowest fat acidity and microbial infection is evident while storing wheat grains up to 4 months improved protein and gluten content, water absorption capacity, FQN and chapatti quality score. Wheat grains when stored up to 8 months showed improvement in PSI, flour yield, gluten content and dough stability. Twelve months storage of wheat grains showed improvement in flour yield, protein content and farinograph quality number. Storage container was the most important factor of this study, which greatly affected the quality of stored grains. It was observed that grains stored in earthen pots retained most of the quality characteristics i.e. lowest moisture content, highest test weight, flour yield, water absorption capacity, chapatti quality score as well as lowest microbial count. The second suitable storing material was cotton bag. Grains stored in cotton bags showed lowest moisture, high test weighs, flour yield, gluten content and appropriate falling number. Polypropylene bags may be ranked as third showing the highest gluten, dough stability, farinograph quality number with the lowest fat acidity in the stored grains. Grains in jute bags exhibited lower fat acidity, highest dough stability and better chapatti quality score whereas grains in tin pots found to have lower fat acidity, higher water absorption and better chapatti quality score. xxIt was interesting to note that particle size index was the only quality parameter that not affected by any of the factors and their interactions. Highest flour yield could be obtained from Chakwal-97 and Margalla-99 after storing these varieties in earthen pots for 4 months whereas for Wafaq-2001 this quality was maintained up to 12 months when stored in cotton bags. It is concluded that earthen pots are suitable for retaining better values for maximum numbers of all the quality parameters studied during this research followed by cotton bags. Cotton bags were better to store these three varieties up to one year by keeping moisture at lower side and higher test weight.