Physical properties of brittle foods, such as almonds, will impact their chemical and enzymatic hydrolysis during gastrointestinal digestion through control of fracture and structural breakdown. As food particles are broken down, they have a larger surface area exposed for chemical and enzymatic hydrolysis in addition to nutrient release from broken cells. Previous studies have found that the metabolizable energy of almonds may be related to the fracture properties of the almond particles; almonds that fractured into fewer, larger particles during uniaxial compression had a lower metabolizable energy. As such, it is critical to understand the relationship between physical properties, fracture properties during compression, and nutrient release and digestion in brittle foods, such as almonds. The aim of this study was to quantify the changes in fracture properties and digestibility in almonds that were soaked in water from 8 – 24 h. Almonds were soaked in water (10 almonds:100 mL deionized water) at room temperature (~23°C) and at refrigeration temperature (~4°C). After soaking periods of 8, 10, 12, 16, and 24 h almonds were removed from the soaking water. Fracture properties were measured by uniaxial compression (30 mm/s, 71% strain); the resulting particle size distribution was quantified through image analysis. Raw almonds (unsoaked) had a median particle area of 18.8 mm<sup>2</sup>, which significantly increased after soaking for 12 and 24 hours at 23°C to 67.6 and 53.2 mm<sup>2</sup>, respectively. The particle size increase was the result of almond kernels fracturing into a smaller number of larger particles. Compared to unsoaked samples (that fractured into 78 particles), the soaked almonds fractured into 18-19 particles after 12-24 h soaking. These results indicate that soaking of almonds modifies their physical properties, which may result in differences in digestibility and metabolizable energy.

Physical property influence on almond fracture properties and digestibility

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.