Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product. / Master of Science (Hons) (Food Science and Nutrition)
| Identifer | oai:union.ndltd.org:ADTP/181984 |
| Date | January 1994 |
| Creators | Chitundu, Elizabeth Malama, University of Western Sydney, Hawkesbury, Faculty of Science and Technology, School of Food Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Source | THESIS_FST_SFS_Chitundu_E.xml |
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