Impact of Air-Drying Temperature on Antioxidant Properties and ACE-Inhibiting Activity of Fungal Fermented Lentil Flour

In vitro digestibility and angiotensin converting enzyme (ACE) inhibitory activity of solid-state fermented fava beans (Vicia faba L.)

Reducing the content of quickly absorbed carbohydrates and saturated fats in snack formulations while increasing the consumption of high-quality proteins are effective strategies to prevent obesity in childhood. Thus, the nutritional value, digestibility, and functionality of fava beans (Vicia faba L.) fermented with Pleurotus ostreatus were examined as potential ingredients for food design. Solid-state fermentation enhanced the protein content by 16% with a rise in essential (25%) and non-essential (15%) amino acids while decreasing total carbohydrate content and tannin levels. Moreover, fermentation modified the amino acid profile released during digestion, increasing amino acids such as valine, isoleucine, and threonine, which are vital for health and development in childhood. Furthermore, the bioaccessible fraction of the fermented bean showed a 60% of ACE inhibition and improved magnesium bioaccessibility. Consequently, fava beans fermented with Pleurotus ostreatus emerged as a new ingredient in the development of new protein-rich snacks tailored for children and adolescents.

Protein digestibility and ACE inhibitory activity of fermented flours in older adults and standard gastrointestinal simulation

Consumption of essential amino acids responsible for muscle protein synthesis is important in preventing sarcopenia among older individuals. This population may experience gastrointestinal disorders that inhibit protein digestibility, making it crucial to address. Therefore, solid-state fermentation (SSF) using Pleurotus ostreatus and air drying has been suggested as a means of improving the protein digestibility of lentils and quinoa. SSF combined with air drying at 70 °C resulted in a slight increase in protein hydrolysis compared to unfermented samples. SSF was found to boost the proportion of small peptides to 35 %. Following digestion, SSF and drying yielded bioactive peptides of 1400 and 450 Da, with a range of 11 % to 28 %, respectively, and peptides < 190 Da making up 60 % of the total. SSF promoted valine, leucine, and isoleucine generation; however, hot air drying reduced free amino acids due to the amino acid-reducing sugar bonding but was never lower than the initial content of its unfermented counterpart. Furthermore, SSF and drying at 70 °C improved the release of hydrophobic amino acids (>70 mg/g dry basis) and negatively charged amino acids (>20 mg/g dry basis) in lentils during digestion. The SSF samples exhibited lower angiotensin converting enzyme (ACE) inhibitory activity, ≤35 %, compared to unfermented flours after digestion. However, the ACE inhibitory activity increased in SSF-dried samples, in part because of melanoidins generated during drying. Finally, lower values of protein digestibility and thus smaller peptides, amino acid profile, and ACE inhibitory activity of fermented flours were found in the older adult digestion model.

Flours from fermented lentil and quinoa grains as ingredients with new techno-functional properties

The need to provide novel, nutritious plant-based products requires seeking high-value, sustainable protein sources, like quinoa and lentils, having an increased digestibility and lacking antinutrients. Fungal fermentation has evidenced enhanced nutritional value of flours obtained from these grains. However, research into techno-functional properties, essential to the new product development, is lacking. This study investigated the techno-functional properties of flours made from lentil and quinoa after fermenting them with Pleurotus ostreatus and subjecting them to two drying techniques (lyophilisation and hot air drying). In both cases, the fermentation led to noteworthy improvements in swelling and water holding capacity, especially in those lyophilised than those dried. In contrast, the emulsifying, foaming, thickening, and gelling capacities decreased significantly. The loss of abilities was more severe for dried grains than for lyophilized ones. The thermomechanical analysis of the fermented flours showed lower thickening and gelling potential compared to untreated flours. Microscopy images revealed that the state and structure of starch granules were affected by both fermentation and drying processes. Starch granules in lentils were partly pre-gelatinised and trapped in the cotyledon cell, resulting in limited thickening and gelling abilities. In contrast, in quinoa, starch underwent pre-gelatinisation and retrogradation during the fermentation process, promoting the production of resistant starch and increasing fibre content. This study presents the potential of treated flours as ingredients possessing unique attributes compared to protein and fibre-rich conventional products.

Volatile profile of quinoa and lentil flour under fungal fermentation and drying

Solid-state fermentation reportedly improves the nutritional and sensory properties of legumes and pseudocereals. This study examined changes in the volatile profile using HS-SPME-GC-MS of two varieties of lentil and quinoa flour fermented with Pleurotus ostreatus and dried using hot-air drying and lyophilisation. Fermentation significantly increased the volatile profile. Pardina lentil flour showed a 570% increase in its volatile profile, and 10 compounds were created. In white quinoa, the total area rose from 96 to 4500, and 30 compounds were created. Compounds such as 1-octen-3-ol, benzaldehyde, 3-octanone and hexanal were generated during fermentation, providing a sweet, grassy, cocoa flavour. Hot-air drying led to decrease of over 40% in total peak area. Dried fermented flour retained higher levels of compounds that provide a sweet, cocoa aroma. Air-drying temperature had no significant influence on the volatile profile. This a allows the inclusion of these flours in a wide variety of food products.

In Vitro Digestion Assessment (Standard vs. Older Adult Model) on Antioxidant Properties and Mineral Bioaccessibility of Fermented Dried Lentils and Quinoa

The growing number of older adults necessitates tailored food options that accommodate the specific diseases and nutritional deficiencies linked with ageing. This study aims to investigate the influence of age-related digestive conditions in vitro on the phenolic profile, antioxidant activity, and bioaccessibility of minerals (Ca, Fe, and Mg) in two types of unfermented, fermented, and fermented dried quinoa and lentils. Solid-state fermentation, combined with drying at 70 °C, significantly boosted the total phenolic content in Castellana and Pardina lentils from 5.05 and 6.6 to 10.5 and 7.5 mg gallic acid/g dry weight, respectively, in the bioaccessible fraction following the standard digestion model, compared to the unfermented samples. The phenolic profile post-digestion revealed elevated levels of vanillic and caffeic acids in Castellana lentils, and vanillic acid in Pardina lentils, while caffeic acids in Castellana lentils were not detected in the bioaccessible fraction. The highest antioxidant potency composite index was observed in digested fermented dried Castellana lentils, with white quinoa samples exhibiting potency above 80%. Mineral bioaccessibility was greater in fermented and fermented dried samples compared to unfermented ones. Finally, the digestive changes that occur with ageing did not significantly affect mineral bioaccessibility, but compromised the phenolic profile and antioxidant activity.