How postharvest variables in the pulse value chain affect nutrient digestibility and bioaccessibility

Pulses are increasingly being put forward as part of healthy diets because they are rich in protein, (slowly digestible) starch, dietary fiber, minerals, and vitamins. In pulses, nutrients are bioencapsulated by a cell wall, which mostly survives cooking followed by mechanical disintegration (e.g., mastication). In this review, we describe how different steps in the postharvest pulse value chain affect starch and protein digestion and the mineral bioaccessibility of pulses by influencing both their nutritional composition and structural integrity. Processing conditions that influence structural characteristics, and thus potentially the starch and protein digestive properties of (fresh and hard-to-cook [HTC]) pulses, have been reported in literature and are summarized in this review. The effect of thermal treatment on the pulse microstructure seems highly dependent on pulse type-specific cell wall properties and postharvest storage, which requires further investigation. In contrast to starch and protein digestion, the bioaccessibility of minerals is not dependent on the integrity of the pulse (cellular) tissue, but is affected by the presence of mineral antinutrients (chelators). Although pulses have a high overall mineral content, the presence of mineral antinutrients makes them rather poorly accessible for absorption. The negative effect of HTC on mineral bioaccessibility cannot be counteracted by thermal processing. This review also summarizes lessons learned on the use of pulses for the preparation of foods, from the traditional use of raw-milled pulse flours, to purified pulse ingredients (e.g., protein), to more innovative pulse ingredients in which cellular arrangement and bioencapsulation of macronutrients are (partially) preserved.