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United States Department of Agriculture

Agricultural Research Service

Research Project: Dietary Modulation of Immune Function and Oxidative Stress

Location: Immunity and Disease Prevention Research Unit

Title: Gastric digestion of raw and roasted almonds in vivo

Authors
item Bornhorst, Gail -
item Roman, Maxine -
item Rutherfurd, Shane -
item BURRI, BETTY
item Singh, R. Paul -
item Moughan, Paul -

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2013
Publication Date: December 14, 2013
Citation: Bornhorst, G., Roman, M., Rutherfurd, S.M., Burri, B.J., Singh, R., Moughan, P.J. 2013. Gastric digestion of raw and roasted almonds in vivo. Journal of Food Science. 78:H1807-H1813.

Interpretive Summary: Almonds are good sources of essential fats, protein, and vitamin E. The influence of roasting on the digestion of almonds has received little attention. We studied the digestive processes of pigs fed a single meal of either raw or roasted almonds. Pigs are a common model for human digestion. Gastric emptying did not differ between raw and roasted almonds. Roasting almonds also did not change gastric pH, plasma glucose or triglyceride levels. However, roasting changed the way that proteins were digested from almonds. Roasted and raw almonds were distributed differently in the stomach. Roasting decreased the vitamin E content of the almonds in our study. Not surprisingly, then, the amount of vitamin E absorbed into blood after eating roasted almonds was less than the amount after eating raw almonds.

Technical Abstract: Almonds are an important dietary source of lipids, protein, and alpha-tocopherol. It has been demonstrated that the physical form of almond kernels will affect their digestion and absorption, but the influence of thermal processes on the digestion of almonds has received little attention. The objectives of this study were to examine the gastric emptying and nutrient composition of gastric chyme from pigs (used as a model for the adult human) fed a single meal of either raw or roasted almonds during a 12 hr postprandial period. Concentrations of glucose, triglycerides, and alpha-tocopherol in peripheral plasma during the 12 hr postprandial period were determined. For dry matter and lipid, the gastric emptying profile was not different between raw and roasted almonds. Roasting almonds also did not influence gastric pH, or plasma glucose or triacylglycerol levels. In contrast, the gastric emptying profile for protein differed (p < 0.01) between the two almond types and intragastric protein content exhibited segregation (p < 0.001) throughout the stomach, with raw almonds having a higher level of segregation compared to roasted almonds. Postprandial plasma alpha-tocopherol levels were greater (p < 0.001) after consumption of raw almonds, most likely as a result of the higher concentration of alpha-tocopherol in raw almonds compared to roasted almonds. Roasting of almonds did not influence the overall gastric emptying process, but did lead to differences in the distribution of protein in the stomach and to the gastric emptying of protein.

Last Modified: 9/10/2014
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