Reduced lipid pecans: chemical alterations and implications for quality maintenance during storage
1999
Kanamangala, R.V. | Maness, N.O. | Smith, M.W. | Brusewitz, G.H. | Knight, S. | Chinta, B.
The unextracted and reduced lipid (supercritical carbon dioxide extraction of 22% and 27% (w/w) of total lipids) pecan [Carya illinoinensis (Wangenh.) K. Koch] kernels packaged in 21% O(2), 79% N(2) were analyzed for color, hexanal, sensory, fresh weight, and lipid class changes periodically during 37 weeks of storage at 25 degrees C and 55% relative humidity. Pecan nutmeats were lightened by partial lipid extraction. The pecan testa darkened (decreasing chromameter L(*)) with storage time. Most color changes occurred in the first 18 weeks. Hexanal concentration of reduced-lipid pecans was negligible throughout storage, while unextracted pecans reached excessive levels by week 22 of storage. Hexanal concentration, indicative of rancidity, was in agreement with sensory analysis results with the hexanal threshold level for objectionable rancidity ranging from 7 to 11 mg kg(-1) pecans. Weight change was negligible during storage, except in 27% reduced-lipid pecans. Free fatty acids increased with storage and were significantly higher in unextracted pecans than the reduced-lipid pecans at 0, 10, 18, 32, and 37 weeks of storage. Shelf life of pecans with partial lipid extraction was longer than unextracted pecans. In addition to decreasing the total amount of lipid available for oxidation, the free fatty acid lipid component that correlated with the development of rancidity was reduced by extraction.
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