Direct enzymatic hydrolysis of solid wheat straw with endo-xylanases: Effect of the temperature on the hemicellulose release and the product profile modulation.

Prebiotics are non-digestible compounds that promote intestinal microbiota growth and/or activity. Xylooligosaccharides (XOS) are new prebiotics derived from the hemicellulose fraction of lignocellulosic materials. Challenges in using those materials as sources for prebiotic compounds lie in the hemicellulose extraction efficiency and the safety of those ingredients. In this sense, this work aims to optimize hemicellulose extraction and XOS production through direct enzymatic hydrolysis of alkali pre-treated wheat straw without undesired byproducts. By increasing the temperature of the enzymatic step from 40 °C to 65 °C we achieved an improvement in the extraction yield from 55 % to 80 %. Products with different degrees of polymerization were also noticed: while XOS ≤ X6 where the main products at 40 °C, a mixture of long arabinoxylan derived polymers (ADPo) and XOS ≤ X6 was obtained at 65 °C, irrespective of the extraction yield. Thus, a modulatory effect of temperature on the product profile is suggested here. Among the XOS ≤ X6 produced, X2-X3 were the main products, and X4 was the minor one. At the end of the hydrolysis, 146.7 mg XOS per gram of pre-treated wheat straw were obtained.

Microfluidics potential for developing food-grade microstructures through emulsification processes and their application.

The food sector continues to face challenges in developing techniques to increase the bioavailability of bioactive chemicals. Utilising microstructures capable of encapsulating diverse compounds has been proposed as a technological solution for their transport both in food and into the gastrointestinal tract. The present review discusses the primary elements that influence the emulsification process in microfluidic systems to form different microstructures for food applications. In microfluidic systems, reactions occur within small reaction channels (1-1000 µm), using small amounts of samples and reactants, ca. 102-103 times less than conventional assays. This geometry provides several advantages for emulsion and encapsulating structure production, like less waste generation, lower cost and gentle assays. Also, from a food application perspective, it allows the decrease in particle dispersion, resulting in a highly repeatable and efficient synthesis method that also improves the palatability of the food products into which the encapsulates are incorporated. However, it also entails some particular requirements. It is important to obtain a low Reynolds number (Re < approx. 250) for greater precision in droplet formation. Also, microfluidics requires fluid viscosity typically between 0.3 and 1400 mPa s at 20 °C. So, it is a challenge to find food-grade fluids that can operate at the micro-scale of these systems. Microfluidic systems can be used to synthesise different food-grade microstructures: microemulsions, solid lipid microparticles, microgels, or self-assembled structures like liposomes, niosomes, or polymersomes. Besides, microfluidics is particularly useful for accurately encapsulating bacterial cells to control their delivery and release on the action site. However, despite the significant advancement in these systems' development over the past several years, developing and implementing these systems on an industrial scale remains challenging for the food industry.

Development and sensory test of a dairy product with ACE inhibitory and antioxidant peptides produced at a pilot plant scale.

A scale-up process was carried out to obtain potent bioactive peptides from whey protein through a simple hydrolysis process. The scale-up was satisfactory, with results similar to those obtained at lab scale: a fraction of peptides < 1 kDa with ACE inhibitory activity of 18.44 ± 2.47 µg/mL, a DPPH value of 69.40 ± 0.44%, and an ORAC value of 3.37 ± 0.03 µmol TE/mg protein. The peptide sequences responsible for the ACE inhibitory activity were also similar to those identified at lab scale: PM, LL, LF, HFKG and PT. The hydrolysate was used as a functional ingredient in a low-fat yoghurt. The consumer sensory taste panel found no significant difference (p > 0.05) between the bitterness of the control and the functional yoghurt, and about 50% of consumers would buy it. The hydrolysate maintained its bioactivities for 4 months at -20 °C (after thawing and pasteurisation), and for 1 week in yoghurt at 4 °C.