Release and Bioaccessibility of Lipophilic Nutrients from Raw and Processed Almonds during Digestion

The food matrix from which lipophilic nutrients, such as carotenoids and vitamin E, are derived or incorporated into has an impact on their release and bioaccessibility in the digestive system. The objective of this research was to assess the effect of food matrix on the release and bioaccessibility of selected lipophilic nutrients. Two digestion studies were conducted to achieve this objective. An in vitro digestion study was conducted to determine the effect of encapsulation on the release and bioaccessibility of beta-carotene from fortified almond butter. An in vivo digestion study was conducted to determine the effect of roasting on the absorption of vitamin E from almonds using a pig model. For the in vitro study, two types of fortifiers were investigated: beta-carotene oil (non-encapsulated) and alginate-chitosan capsules containing beta-carotene oil (encapsulated). Shaking water bath and Human Gastric Simulator (HGS) digestion models assessed the impact of gastric peristalsis on the release of beta-carotene. Bioaccessibility of beta-carotene was determined by the concentration in the micelle fraction. There was greater release of beta-carotene from non-encapsulated fortified almond butter in the HGS model (87.1%) due to peristalsis than the shaking water bath model (51.0%). Overall, more beta-carotene was released from encapsulated fortified almond butter. However, more beta-carotene was recovered from the micelle fraction of non-encapsulated fortified almond butter. Non-encapsulated beta-carotene oil appears to be the preferred method of fortification of almond butter due to its higher bioaccessibility.;For the in vivo digestion study, 72 male pigs were fed a diet of raw or roasted almonds and sacrificed at designated time intervals after meal consumption (20 min, 1 h, 3 h, 5 h, 8 h, 12 h). Plasma (post-mortem) and liver alpha-tocopherol concentration were assessed to determine relative vitamin E status. Pigs fed raw almonds showed greater plasma (p<0.0001) and liver alpha-tocopherol concentration than pigs fed roasted almonds. However, this difference was mostly due to the difference in alpha-tocopherol concentrations in the diet rather than the structural changes that occur to almonds during roasting. Overall, this research demonstrates that food matrix can have an effect on the release and bioaccessibility of lipophilic nutrients.