The Effect of “Activating” Nuts on Fat and Mineral Content

Abstract

Background: Nuts are a rich source of a number of nutrients, including cis-unsaturated fats, which confer a cardioprotective effect. In recent years, consumers have been bombarded with messages from popular media that claim the need for nuts to be “activated” – a process whereby nuts are first soaked and then dried – in order to elicit their health benefits. However, previous research has failed to demonstrate practically significant changes in phytate concentrations with “activating” nuts. In fact, research suggested a reduction in the amount of minerals, such as iron, calcium, zinc, phosphorous, and magnesium, after the “activating” process. It must be acknowledged though, that not all of the minerals contained in high quantities in nuts have been examined. Of interest also, is that there has been no published research investigating the effects of nut “activation” on fat content. This is an important knowledge gap, given the abundance of cis-unsaturated fats in nuts, and its crucial role in lowering cholesterol.

Objective: To determine the effects of “activating” whole and chopped almonds, hazelnuts, peanuts, and walnuts on fat and mineral (copper, manganese, molybdenum, and nickel) concentrations, both with and without adjustment for moisture loss.

Design: Both whole and chopped forms of the four varieties of nuts were soaked for 12 hours and dried at 65˚C for 24 hours, based on commonly used “activating” protocols. The fat and mineral content of “activated” or treated nuts were compared with untreated nuts (control). The fat content of untreated and “activated” nuts was measured by the Soxtec method, and minerals by inductively coupled plasma mass spectrometry.

Results: When compared to untreated nuts, the fat content of all “activated” whole and chopped nuts was statistically significantly lower (whole: 3.2%-12.2% lower; chopped: 1.6%-12.9% lower; all p ≤ 0.049), except for that of whole almonds (p = 0.083). These differences were more pronounced and remained statistically significant after adjustment for moisture loss (whole: 8.5-14.9% lower, chopped: 6.1-15.9% lower, all p ≤ 0.008). Chopped almonds were the only nuts which contained statistically significantly lower amounts of fat than their “activated” whole counterparts (“unadjusted”: 7.5% lower, “adjusted”:7.8% lower, both p < 0.001). No statistically significant differences in copper, manganese, and molybdenum content were observed between all possible comparisons, except for the manganese content of “activated” chopped walnuts, which was statistically significantly lower than that of untreated walnuts and “activated” whole walnuts (24.8% lower and 14.9% lower respectively, both p ≤ 0.018). Following “activating” process, the nickel content of chopped hazelnuts was 11.5% and 16.5% lower compared to untreated and “activated” whole hazelnuts respectively (both p ≤ 0.025). Similarly to fat content, losses in minerals were augmented after adjustment for water loss.

Conclusion: While “activating” process has little effect on mineral concentrations examined in this study, the “activated” nuts do contain lower amounts of fat (an average of approximately 8 g lower per 100 g for four nut types). Given the cholesterol-lowering effects of nuts is dose-dependent, the lower fat content of “activated” nuts may attenuate the hypocholesterolaemic properties of nuts, especially at higher intake. Therefore, the present study does not support the claims that “activation” process would improve the beneficial effects of regular nut consumption.