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

From static to semi-dynamic in vitro digestion conditions relevant for the older population: starch and protein digestion of cooked lentils

In the context of adequately feeding the rising older population, lentils have an important potential as sources of (plant-based) protein as well as slowly digestible bio-encapsulated starch and fibre. This study evaluated in vitro digestion of protein and starch in lentils under conditions representing the gastrointestinal tract of older adults. Both static and semi-dynamic simulations were applied to analyze the effect of specific gastrointestinal conditions (healthy versus older adult) on macronutrient digestion patterns. Gastric proteolysis was strongly dependent on applied gastric pH (gradient), leading to a lower extent of protein hydrolysis for simulations relevant for older adults. Fewer and smaller (lower degree of polymerization, DP) bioaccessible peptides were formed during gastric proteolysis under older adult compared to healthy adult conditions. These differences, developed during the in vitro gastric phase, were compensated during small intestinal digestion, yielding similar final proteolysis levels regardless of the applied simulation conditions. In contrast, in the presence of saliva, amylolysis was generally accelerated under older adult conditions. Moreover, the current work highlighted the importance of considering saliva (or salivary amylase) incorporation in simulations where the applied gastric pH (gradient) allows salivary amylase activity. Under both healthy and older adult conditions, in vitro starch hydrolysis bio-encapsulated in cotyledon cells of cooked lentils was attenuated, compared to a white bread reference.

Enhancing Nutritional Profile of Pasta: The Impact of Sprouted Pseudocereals and Cushuro on Digestibility and Health Potential

We hypothesized that optimizing the formulation of pasta by incorporating sprouted pseudocereal flours, specifically quinoa (Chenopodium quinoa Willd) or kiwicha (Amaranthus caudatus L.) and cushuro (Nostoc sphaericum Vaucher ex Bornet & Flahault) flours, could offer the potential to simultaneously enhance nutritional quality and health-promoting properties in pasta. In this study, our objective was to optimize the formulation of composite flour (a ternary blend of wheat, sprouted pseudocereal, and cushuro flours) using a mixture composite design to maximize total soluble phenolic compounds (TSPC), γ-aminobutyric acid (GABA), antioxidant activity, and mineral bioaccesilability by reducing phytic acid (PA) content. Two optimal formulations were identified: one consisting of 79% wheat flour (WF), 13% SQF, and 8% CuF (oPQC), and the other composed of 70% WF, 15% SKF, and 15% CuF (oPKC). These optimized pastas exhibited reduced starch content and notably higher levels of total dietary fiber (1.5-3.61-fold), protein (1.16-fold), fat (1.3-1.5-fold), ash (2.2-2.7-fold), minerals (K, Na, Fe, Zn, Mg, Mn, and Ca), PA (3-4.5-fold), TSPC (1.3-1.9-fold), GABA (1.2-2.6-fold), and ORAC (6.5-8.7-fold) compared to control pasta (100% WF). Notably, the glycemic index of oPQC (59.8) was lower than that of oPKC (54.7) and control pasta (63.1). The nutritional profile of the optimized pasta was largely retained after cooking, although some significant losses were observed for soluble dietary fiber (18.2-44.0%), K (47.5-50.7%), Na (42.5-63.6), GABA (41.68-51.4%), TSPC (8-18%), and antioxidant activity (45.4-46.4%). In vitro digestion of cooked oPQC and oPKC demonstrated higher bioaccessible content of GABA (6.7-16.26 mg/100 g), TSPC (257.7-261.8 mg GAE/100 g), Ca (58.40-93.5 mg/100 g), and Fe (7.35-7.52 mg/100 g), as well as antioxidant activity (164.9-171.1 µmol TE/g) in intestinal digestates compared to control pasta. These findings suggest that the incorporation of sprouted pseudocereals and cushuro flour offers a promising approach to enhance the nutritional quality and bioactive content of wheat-based pasta, potentially providing health benefits beyond traditional formulations.

Nutritional and chemical composition of Alpinia zerumbet leaves, a traditional functional food

Alpinia zerumbet, a species of the Zingiberaceae family, is a common plant in tropical and subtropical areas used in traditional medicine to treat various diseases and also included as food in the traditional Okinawan diet (Japan). The leaves and rhizomes of this plant are used as spice and flavoring in foods such as rice, meats, and pasta. Studies of the chemical and nutritional characteristics of fresh leaves and of leaves submitted to thermal treatments such as boiling and steaming are lacking. In the current study, the leaves of A. zerumbet were subjected to boiling or steaming for 10, 20, and 30 min as part of the thermal treatments. The study also provides noteworthy results regarding the proximate composition, physical-chemical data, minerals, phenolic compounds, antioxidant activity, volatile compounds, and LC-MS chromatographic profiles of the extracts produced with fresh leaves and with thermal treatments. The carbohydrate content of A. zerumbet leaves improved during the thermal treatments, showing an increase after steaming (18.86 to 19.79%) and boiling for 30 min (25.85%). After boiling treatment for 20 min, a significant amount of protein was found (6.79%) and all heat treatments resulted in low content of lipid (<1.0%). The boiling treatment for 10 min (BT10) resulted in the highest concentrations of total phenolic components (TPC), 339.5 mg/g, and flavonoids (TF), 54.6 mg/g, among the three thermal treatments (BT10, BT20 and BT30). The results of the steaming treatments (ST 10, 20, and 30 min) differed, with ST20 leading to higher TPC (150.4 mg/g) and TF (65.0 mg/g). The quantity of total phenolics and flavonoids, as well as the antioxidant activity, were significantly affected by the cooking method and the length of time of sample exposure to heat. The samples boiled for 30 and 10 min had higher concentrations of antioxidant activity as measured by the phosphomolybdenum and DPPH methods (151.5 mg/g of extract and 101.5 μg/mL, respectively). Thirty-eight volatile organic compounds (VOCs) were identified by chromatographic analysis of fresh and thermally treated leaves of A. zerumbet. Terpenoids were the predominant class of volatile compounds in the fresh leaves and in all thermal treatments. p-Cymene, 1,8-cineole, 4-terpineol, linalool, α-copaene and β-bisabolene have the greatest impact on overall aroma perception, with odor activity values (OAV) greater than five. Among the phenolic compounds identified by LC-HRMS in the extracts of fresh and thermally treated leaves were proanthocyanidins, (+) catechin, (-) epicatechin, quercetin-3-O-glucoronide, isorhamnetin-3-O-glucoronide, kaempferol-3-O-rutinoside, pinocembrin, alpinetin, pinostrobin, and other compounds. The present results support the traditional use of this plant as a potential food with properties that certainly contribute to health improvement.

Enzyme cocktail with hyperactive lipase through solid-state fermentation by the novel strain Penicillium sp. Y-21

Lipase is a kind of industrial enzyme preparation with various catalytic abilities and is widely used in food, energy, medicine and other fields. To increase lipase and enzyme cocktail activity through solid-state fermentation, the novel strain Penicillium sp. Y-21 was obtained through ethyl methanesulfonate (EMS) mutation from the novel strain Y, which was isolated from soils. Solid-state fermentation by strain Y-21 using agricultural byproducts was carried out in tray bioreactors. The optimum culture composition for enzyme cocktail fermentation was soybean meal 20 g, 3% (w/w) glucose, 1% (w/w) peptone, 5% (w/w) lard, 0.04% (w/w) CaCl2, 0.04% (w/w) FeCl3, 28 °C for 72 h. The enzyme cocktail produced by strain Y-21 is a kind of multienzyme complex, containing xylanase, glucanase, acidic protease, pectinase, cellulase and lipase, and their enzymatic activities (unit: U g-1) were 8000, 6000, 8000, 2000, 3000 and 120, respectively. During the fermentation process, the lipase coding genes pel, pha, and p12 were also studied and amplified from the RNA of Penicillium sp. Y-21 by RT-PCR. The results showed that the pel gene played an important role in enzyme production. Afterwards, an enzyme cocktail can be added to chicken feed as an additive, which improves animal growth and feed efficiency.

In vitro determination of the protein quality of maize varieties cultivated in Malawi using the INFOGEST digestion method

There is an urgent need to alleviate protein deficiencies in low-income countries where cereal-based diets dominate. The objective of this study was to use the INFOGEST static digestion method and a recently established analytical workflow to determine the in vitro amino acid digestibility and protein quality of seven maize varieties grown in Malawi. Protein quality was measured using the in vitro digestible indispensable amino acid score (DIAAS). Amino acid digestibility was higher for the dehulled, low fibre, provitamin A maize flour (66%), compared to whole grain maize flours (51-61%), suggesting that the presence of fibre reduced digestibility (p < 0.05). Lysine was the limiting amino acid in all varieties, with the following DIAAS values for each variety; Provitamin A maize - 24, SC 719 - 32, Mtsikinya - 37, SC 167 - 39, Quality protein maize (QPM) - 40, Bantum - 40, SC 403 - 44. In addition to the variety of maize, protein quality was dependent on the level of processing and the agronomic practice applied with higher protein quality for the SC 403 variety in which zinc enriched fertilizer was applied. Comparing protein quality data with published in vivo data showed that DIAAS data were in closer agreement than amino acid digestibility data, which was slightly lower than published values, with mean in vitro amino acid digestibilities of 56-70% compared to a mean in vivo value of 77%. Overall, the in vitro method was able to correctly predict both the direction and magnitude of response. The INFOGEST digestion method coupled with the new analytical workflow will therefore be useful in the screening of high protein cereal crops and subsequent development of cereal-based foods with high protein quality.

Protein blends and extrusion processing to improve the nutritional quality of plant proteins

Plant proteins have low protein nutritional quality due to their unbalanced indispensable amino acid (IAA) profile and the presence of antinutritional factors (ANFs) that limit protein digestibility. The blending of pulses with cereals/pseudocereals can ensure a complete protein source of IAA. In addition, extrusion may be an effective way to reduce ANFs and improve protein digestibility. Thereby, we aimed to improve the protein nutritional quality of plant protein ingredients by blending different protein sources and applying extrusion processing. Protein blends were prepared with pea, faba bean, quinoa, hemp, and/or oat concentrates or flours, and extrudates were prepared either rich in pulses (texturized vegetable proteins, TVPs) or rich in cereals (referred to here as Snacks). After extrusion, all samples showed a reduction in trypsin inhibitor activity (TIA) greater than 71%. Extrusion caused an increase in the total in vitro protein digestibility (IVPD) of TVPs, whereas no significant effect was shown for the snacks. According to the molecular weight distribution, TVPs presented protein aggregation. The results suggest that the positive effect of decreased TIA on IVPD is partially counteracted by the formation of aggregates during extrusion which restricts enzyme accessibility. After extrusion, all snacks retained a balanced amino acid score whereas a small loss of methionine + cysteine was observed in the TVPs, resulting in a small reduction in IAA content. Thus, extrusion has the potential to improve the nutritional quality of TVPs by reducing TIA and increasing protein digestibility.

Hard-to-cook phenomenon in common legumes: Chemistry, mechanisms and utilisation

Future dietary protein demand will focus more on plant-based sources than animal-based products. In this scenario, legumes and pulses (lentils, beans, chickpeas, etc.) can play a crucial role as they are one of the richest sources of plant proteins with many health benefits. However, legume consumption is undermined due to the hard-to-cook (HTC) phenomenon, which refers to legumes that have high resistance to softening during cooking. This review provides mechanistic insight into the development of the HTC phenomenon in legumes with a special focus on common beans and their nutrition, health benefits, and hydration behaviour. Furthermore, detailed elucidation of HTC mechanisms, mainly pectin-cation-phytate hypothesis and compositional changes of macronutrients like starch, protein, lipids and micronutrients like minerals, phytochemicals and cell wall polysaccharides during HTC development are critically reviewed based on the current research findings. Finally, strategies to improve the hydration and cooking quality of beans are proposed, and a perspective is provided.

Associating Compositional, Nutritional and Techno-Functional Characteristics of Faba Bean (Vicia faba L.) Protein Isolates and Their Production Side-Streams with Potential Food Applications

Faba beans (Vicia faba L.) show exciting prospects as a sustainable source of protein and fibre, with the potential to transition to a more sustainable food production. This study reveals the compositional, nutritional and techno-functional characteristics of two protein isolates from faba beans (Vicia faba L.), a high-starch fraction and a high-fibre side-stream. During the analysis of those four ingredients, particular attention was paid to the isolates' protein profile and the side-streams' carbohydrate composition. The isoelectric precipitated protein isolate 1 showed a protein content of 72.64 ± 0.31% DM. It exhibited low solubility but superior digestibility and high foam stability. High foaming capacity and low protein digestibility were observed for protein isolate 2, with a protein content of 71.37 ± 0.93% DM. This fraction was highly soluble and consisted primarily of low molecular weight proteins. The high-starch fraction contained 83.87 ± 3.07% DM starch, of which about 66% was resistant starch. Over 65% of the high-fibre fraction was insoluble dietary fibre. The findings of this study provide a detailed understanding of different production fractions of faba beans, which is of great value for future product development.

How Cooking Time Affects In Vitro Starch and Protein Digestibility of Whole Cooked Lentil Seeds versus Isolated Cotyledon Cells

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.

Studying semi-dynamic digestion kinetics of food: Establishing a computer-controlled multireactor approach

In this work, a multireactor system to study digestion (MuReDi) kinetics is introduced. For this, a custom-made automated system with four independent syringe pumps (BioXplorer 100, H.E.L Group) was acquired. This system consists of multiple, small-scale reactors allowing to study digestion as a function of time and thus to determine digestion kinetics. The different digestion conditions used in the oral, gastric, and small intestinal phase were based on the digestion protocols published by the INFOGEST consortium. We showed that the minimum working volume of a reactor is 30 mL. Besides, repeatability of the digestion kinetics was shown for two food systems: a liquid Ensure® Plus Vanilla drink, and a solid, cooked lentil sample. When comparing static digestion kinetics with semi-dynamic ones, a significantly different digestion pattern was observed. In the static case, a relatively fast hydrolysis rate was observed until a clear plateau was reached. Oppositely, for the semi-dynamic case, a delayed start of the hydrolysis process was noticed. In the gastric phase, this was explained by the decreasing pH and the large pH dependency of pepsin activity. In the small intestine, the lag phase was relatively shorter, yet clearly present. Here we related it to the gradual enzyme (and bile salt) secretion that had to diffuse towards the substrate before hydrolysis could start. Generally, this work showed that the MuReDi system could be used to perform a semi-dynamic digestion approach which largely impacted the overall digestion kinetics. This is important to consider in future in vitro food digestion simulation work to come closer to physiologically relevant digestion kinetics.

In vitro digestion of protein and starch in sponge cakes formulated with pea (Pisum sativum L.) ingredients

This study investigated the in vitro digestion of purified pea fractions (protein isolate and starch) in sponge cakes when compared to unrefined pea flour and to the whole wheat flour and purified maize starch commonly used in the food industry. Proteins in the wheat cake were hydrolysed more rapidly than those in cakes made with either pea flour or a combination of pea proteins and purified starch. In absolute terms, however, more readily bioaccessible protein was released from these pea cakes (by around 40%). By contrast, cakes containing wheat flour or maize starch were more susceptible to amylolysis compared to those based on pea starch in the form of the purified ingredient or whole flour. This could be attributed to a higher proportion of amylose and resistant starch in the pea cakes as well as structural characteristics that might have decelerated enzyme-substrate interactions. Interestingly, similar digestion patterns were observed regarding the purified pea ingredients and unrefined whole pea flour. It was therefore concluded that pea ingredients, and particularly the less purified and thus more sustainable whole pea flour, are promising plant-based alternatives for use in gluten-free baked products.

Utilizing Hydrothermal Processing to Align Structure and In Vitro Digestion Kinetics between Three Different Pulse Types

Processing results in the transformation of pulses’ structural architecture. Consequently, digestion is anticipated to emerge from the combined effect of intrinsic (matrix-dependent) and extrinsic (processed-induced) factors. In this work, we aimed to investigate the interrelated effect of intrinsic and extrinsic factors on pulses’ structural architecture and resulting digestive consequences. Three commercially relevant pulses (chickpea, pea, black bean) were selected based on reported differences in macronutrient and cell wall composition. Starch and protein digestion kinetics of hydrothermally processed whole pulses were assessed along with microstructural and physicochemical characteristics and compared to the digestion behavior of individual cotyledon cells isolated thereof. Despite different rates of hardness decay upon hydrothermal processing, the pulses reached similar residual hardness values (40 N). Aligning the pulses at the level of this macrostructural property translated into similar microstructural characteristics after mechanical disintegration (isolated cotyledon cells) with comparable yields of cotyledon cells for all pulses (41–62%). We observed that processing to equivalent microstructural properties resulted in similar starch and protein digestion kinetics, regardless of the pulse type and (prolonged) processing times. This demonstrated the capacity of (residual) hardness as a food structuring parameter in pulses. Furthermore, we illustrated that the digestive behavior of isolated cotyledon cells was representative of the digestion behavior of corresponding whole pulses, opening up perspectives for the incorporation of complete hydrothermally processed pulses as food ingredients.