Moving from static to more complex in vitro digestion approaches using a hypothesis-based approach to introduce dynamic factors to in vitro models might be indispensable to obtain more physiologically relevant data.
2 July 2022 in Trends in Food Science & Technology
Pulse seeds are nutritious and sustainable matrices with a high level of intrinsic microstructural complexity. They contain high‐quality plant‐based protein and substantial amounts of slowly digestible starch and dietary fiber. Starch and protein in pulses are located inside cotyledon cells that survive cooking and subsequent mechanical disintegration, hence preserving natural nutrient bioencapsulation. In this context, several authors have explored a number of techniques to isolate individual cotyledon cells from these seeds, aiming to unveil their digestive and physicochemical properties. In recent years, isolated pulse cotyledon cells are also being highlighted as promising novel ingredients that could improve the nutritional properties of traditionally consumed food products. Even more, they could enable to implement a strategy for increasing pulse intake in populations where these seeds have not been traditionally consumed. This review mainly focuses on the reported digestive, physicochemical, and technofunctional properties of pulse cotyledon cells isolated through different techniques, preceded by a descriptive summary of the nutritional properties, structural organization, and traditional process chain of pulse seeds. It also offers an outlook of research directions to take, based on the identified research gaps. All in all, it is clear that isolation of pulse cotyledon cells using diverse techniques constitutes a promising strategy for the development of pulse‐based ingredients where natural bioencapsulation of macronutrients is preserved. However, much more research is needed at the level of ingredient characterization to better understand the effect of starting pulse seed material, isolation technique, and isolation conditions on the nutritional and functional properties of the finished product(s) where the isolated cells are (to be) used.
Mineral (Mg, Ca, Fe and Zn) bioaccessibility in common beans was evaluated taking into consideration the common bean food chain from postharvest storage over processing (soaking and cooking) until consumption. Beans were stored under realistic tropical conditions (35 °C and 80% RH) which resulted in significantly different cooking behaviour after 8 weeks compared to freshly harvested beans. Based on postcooking hardness, different storage times were selected: unstored, 8 and 20 weeks. Independently of storage conditions, beans were soaked overnight and cooked for 30, 60 or 120 min. The mineral bioaccessibility decreased with increase in both storage and cooking times. Decrease in mineral bioaccessibility with increasing storage time was proved to be the result of increasing mineral chelation of cell wall polymers (e.g. pectin). Additionally, we hypothesize that by cooking, mineral chelators become more accessible, e.g. through pectin solubilization phenomena, in turn capturing more free minerals leading to a reduced mineral bioaccessibility.
Lentils are sustainable sources of bioencapsulated macronutrients, meaning physical barriers hinder the permeation of digestive enzymes into cotyledon cells, slowing down macronutrient digestion. While lentils are typically consumed as cooked seeds, insights into the effect of cooking time on microstructural and related digestive properties are lacking. Therefore, the effect of cooking time (15, 30, or 60 min) on in vitro amylolysis and proteolysis kinetics of lentil seeds (CL) and an important microstructural fraction, i.e., cotyledon cells isolated thereof (ICC), were studied. For ICC, cooking time had no significant effect on amylolysis kinetics, while small but significant differences in proteolysis were observed (p < 0.05). In contrast, cooking time importantly affected the microstructure obtained upon the mechanical disintegration of whole lentils, resulting in significantly different digestion kinetics. Upon long cooking times (60 min), digestion kinetics approached those of ICC since mechanical disintegration yielded a high fraction of individual cotyledon cells (67 g/100 g dry matter). However, cooked lentils with a short cooking time (15 min) showed significantly slower amylolysis with a lower final extent (~30%), due to the presence of more cell clusters upon disintegration. In conclusion, cooking time can be used to obtain distinct microstructures and digestive functionalities with perspectives for household and industrial preparation.