Electrochemical biosensor for aerobic acetate detection.

There is an increasing demand on alternatives methods to animal testing. Numerous health parameters have been already studied using in vitro devices able to mimic the essential functions of the organs, being the real-time monitoring and response to stimuli their main limitations. Regarding the health of the gut, the short chain fatty acids, and particularly acetate, have emerged as key biomarkers to evaluate gut healthiness and disease development, although the number of acetate biosensors is still very low. This article presents a microbial biosensor based on fully biocompatible materials which is able to detect acetate in aerobic conditions in the range between 11 and 50 mM, and without compromising the viability and function of either bacteria (>90% viability) or mammalian cells (>80% viability). The detection mechanism is based on the metabolism of acetate by Escherichia coli bacteria immobilized on the transducer surface. Ferricyanide is used as a redox mediator to transfer electrons from the acetate metabolism in the bacterial cells to the transducer. High bacterial concentrations are immobilized in the transducer surface (109 cfu mL-1) by electrodeposition of conductive alginate hydrogels doped with reduced graphene oxide. The results show successful outcomes to exploit bacteria as a biosensing tool, based on the use of inkjet printed transducers, biocompatible materials and cell entrapment technologies.

Nutritional and antioxidant changes in lentils and quinoa through fungal solid-state fermentation with Pleurotus ostreatus.

Solid-state fermentation (SSF) may be a suitable bioprocess to produce protein-vegetal ingredients with increased nutritional and functional value. This study assessed changes in phenol content, antinutrient content, biomass production and protein production resulting from the metabolic activity of Pleurotus ostreatus, an edible fungus, in lentils and quinoa over 14 days of SSF. The impact of particle size on these parameters was also assessed because the process was conducted in both seeds and flours. Fungus biomass increased during fermentation, reaching 30.0 ± 1.4 mg/g dry basis and 32 ± 3 mg/g dry basis in lentil grain and flour and 52.01 ± 1.08 mg/g dry basis and 45 ± 2 mg/g dry basis in quinoa seeds and flour after 14 days of SSF. Total protein content also increased by 20% to 25% during fermentation, in all cases except lentil flour. However, the soluble protein fraction remained constant. Regarding phytic acid, SSF had a positive impact, with a progressive decrease being higher in flours than in seeds. Regarding antioxidant properties, autoclaving of the substrates promoted the release of polyphenols, together with antioxidant activity (ABTS, DPPH and FRAP), in all substrates. However, these parameters drastically decreased as fermentation progressed. These results provide scientific knowledge for producing lentil- or quinoa-based ingredients with low antinutrient content enriched with protein fungal biomass.

The potential of fermentation on nutritional and technological improvement of cereal and legume flours: A review.

Nowadays there is an increasing demand for vegetable protein sources as an alternative to that of animal origin, not only for its greater environmental sustainability but also for its relationship with lower risk of suffering cardiovascular diseases. Legumes, cereals and seeds are seen as a good proteinaceous source providing as well dietetic fiber and phytochemicals with antioxidant properties. However, their digestibility and bioavailability are limited by the presence of anti-nutritional factors (ANFs) but susceptible of being improved by soaking, cooking or fermentation. The objective of this work is to review the solid-state and submerged fermentation effect on nutritional and functional properties of legumes, cereals and seeds. The microorganisms involved (bacteria, fungus and yeasts) are able to produce enzymes that degrade ANFs giving rise to more digestible flours with a more interesting nutritional, sensorial and technological profile. Solid-state fermentation is more commonly used for its higher efficiency, accepting agro-industrial residues as substrates and its lower volume of effluents. Fermented legumes had their technological properties enhanced while an increment in antioxidant properties was characteristic of cereals. The present review highlights fermentation of cereals and legumes mainly as a key process that at industrial scale could generate new products with enhanced nutritional and technological properties.

In vitro starch digestibility and fate of crocins in pasta enriched with saffron extract.

This work aims to study the effect of the addition of saffron extract on fresh pasta in-vitro digestibility. Fresh pasta was formulated with different concentrations of saffron extracts (0.2 and 0.4 %w/w), cooked at two different times (1.5 and 3 min), and in vitro digested (oral, gastric and intestinal stages). Oil was added to pasta before digestion to evaluate the presence of lipids on starch and crocin bioaccessibility. Saffron enrichment and oil addition slowed down the digestion of starch, thus, decreasing the glycemic index of pasta. Concentration of saffron and oil addition contributed to crocin release in the digestion fluids, with the opposite effect of cooking time. Isomerization from trans to cis was enhanced by both, cooking and oil addition. Bioaccessibility of total crocins varied from 2.9 ±â€¯1.1, to 97 ±â€¯3%. Finally, the trans:cis isomers distribution was only close to 50:50 in enriched-pasta cooked during 3 min or with oil addition.