The effects of peanut processing on body weight, plasma lipids, and masticatory performance

Fiona McKiernan, Purdue University

Abstract

Observational and clinical intervention data have consistently indicated nut consumption reduces cardiovascular disease risk. However, few studies have assessed whether processing has an impact on the biological and functional properties of nuts and whether this translates into alterations in the cardioprotective effects. Observational studies have generally not differentiated nut varieties, while clinical intervention studies have generally used natural, unprocessed nuts, lightly salted, roasted nuts, or an unspecified nut variety. The purpose for the present research was to investigate the effects of processing (adding flavors, grinding to butter, and roasting) on body weight and plasma lipids. One hundred and eighteen adults, from Brazil, Ghana, and the United States, were randomized to consume 56 g of raw unsalted (n = 23), roasted unsalted (n = 24), roasted salted (n = 23), or honey roasted (n = 24) peanuts, or peanut butter (n = 24) daily for 4 weeks. No other dietary instructions were given to the participants. The processing of peanuts into different forms and flavors did not differentially affect body weight or plasma lipid responses. The peanut intervention significantly reduced total fasting cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglyceride (TAG) concentrations in individuals with the highest levels at baseline, compared to those with normal plasma lipids. No significant changes in body weight were observed. These observations suggest grinding to butter, adding flavors such as salt or sugar, or roasting do not significantly alter the beneficial lipid-lowering effects of peanuts, and do not negatively impact on body weight. The findings also suggest that individuals most at risk of cardiovascular disease due to dyslipidemia will gain the greatest benefit from peanut consumption. The effects of peanut processing on masticatory performance were also explored in the United States sample (n = 39). The surface electrical activity of the masseter muscles was recorded while the participants chewed raw unsalted, roasted unsalted, roasted salted, and honey roasted peanuts, in both fasted and sated conditions. Particle sizes of the pre-swallowing peanut boluses were determined by the multiple sieve method. Masticatory performance was significantly influenced by peanut processing, in both the fasted and sated states. The processed peanuts (roasted unsalted, roasted salted, and honey roasted) were chewed significantly fewer times and required significantly less total muscle activity to prepare for swallowing compared to the unprocessed variety (raw). Additionally, pre-swallowing particle sizes were significantly larger for the processed forms compared to the unprocessed form. Since changes in chewing efficiency and particle size has potential implications for many aspects of nutrition, such as the bioaccessibility of cardioprotective nutrients, these observations warrant further exploration.

Degree

M.S.

Advisors

Mattes, Purdue University.

Subject Area

Nutrition

COinS