Changes of Chemical and Physical Quality Attributes of Macadamia Nuts during Hybrid Drying and Processing

Macadamia nuts are well known for their unique flavor and taste. They contain a high level of monounsaturated fatty acids such as oleic acid, which is claimed to have an effect on reducing blood cholesterol. This study focuses on monitoring the changes in the physical and chemical qualities of macad...

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Bibliographic Details
Published in:	Drying technology Vol. 30; no. 16; pp. 1870 - 1880
Main Authors:	Phatanayindee, Suporntip, Borompichaichartkul, Chaleeda, Srzednicki, George, Craske, John, Wootton, Michael
Format:	Journal Article
Language:	English
Published:	Philadelphia Taylor & Francis Group 15-12-2012 Taylor & Francis Ltd
Subjects:	air drying bags blood cholesterol color composite polymers Drying Drying agents fatty acid composition Fatty acids Flavor Food preservation Food quality free fatty acids Heat pump drying heat pumps Lipids Macadamia nuts Moisture content monitoring Nuts oleic acid peroxide value roasting taste volatile compounds water activity water content
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Summary:	Macadamia nuts are well known for their unique flavor and taste. They contain a high level of monounsaturated fatty acids such as oleic acid, which is claimed to have an effect on reducing blood cholesterol. This study focuses on monitoring the changes in the physical and chemical qualities of macadamia nuts during drying, roasting, and storage. A combination of heat pump drying and tunnel drying was selected for this study to provide a comparison with convectional hot air drying. After completion of all drying treatments, the dried nuts were subjected to roasting at 125°C for 20 min and storage in ethylene vinyl alcohol copolymer (EVOH) bags at 4°C for 3 months. After each stage of processing, nut samples were taken to assess the quality in terms of fatty acids, moisture content, water activity, peroxide value, free fatty acids, color, and volatile compounds. The experimental results showed that drying treatments using heat pump combined with tunnel drying can reduce drying time significantly. It appears that the combination of heat pump and tunnel drying resulted in maintaining the commercially accepted chemical and physical quality characteristics of macadamia nuts in terms of key fatty acid contents, peroxide value, free fatty acid content, and color. Moreover, drying with a heat pump dryer combined with tunnel drying did not increase the content of undesirable volatile compounds in dried macadamia nuts after processing.
Bibliography:	http://dx.doi.org/10.1080/07373937.2012.703275
ISSN:	1532-2300 0737-3937 1532-2300
DOI:	10.1080/07373937.2012.703275