Production of the Polyhydroxyalkanoate PHBV from Ricotta Cheese Exhausted Whey by Haloferax mediterranei Fermentation.

In the last decade, the dairy industry underwent a rapid expansion due to the increasing demand of milk-based products, resulting in high quantity of wastewater, i.e., whey and ricotta cheese exhausted whey (RCEW). Although containing high content of nutritional compounds, dairy by-products are still disposed as waste rather being reintroduced in a new production chain, hence leading to environmental and economic issues. This study proposes a new biotechnological approach based on the combination of membrane filtration and fermentation to produce poly-hydroxyalkanoates (PHA), biodegradable bioplastics candidate as an alternative to petroleum-derived plastics. The protocol, exploiting the metabolic capability Haloferax mediterranei to synthesize PHA from RCEW carbon sources, was set up under laboratory and pilot scale conditions. A multi-step fractionation was used to recover a RCEW fraction containing 12.6% (w/v) of lactose, then subjected to an enzymatic treatment aimed at releasing glucose and galactose. Fermentation conditions (culture medium for the microorganism propagation, inoculum size, time, and temperature of incubation) were selected according to the maximization of polymer synthesis, under in-flasks experiments. The PHA production was then tested using a bioreactor system, under stable and monitored pH, temperature, and stirring conditions. The amount of the polymer recovered corresponded to 1.18 g/L. The differential scanning calorimetry (DSC) analysis revealed the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as the polymer synthesized, with a relatively high presence of hydroxyvalerate (HV). Identity and purity of the polymer were confirmed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron (XPS) spectroscopy analyses. By combining the fractionation of RCEW, one of the most abundant by-products from the agri-food industry, and the use of the halophile Hfx mediterranei, the production of PHBV with high purity and low crystallinity has successfully been optimized. The process, tested up to pilot scale conditions, may be further implemented (e.g., through fed-batch systems) and used for large-scale production of bioplastics, reducing the economical and environmental issues related the RCEW disposal.

Nutritional, Functional, and Technological Characterization of a Novel Gluten- and Lactose-Free Yogurt-Style Snack Produced With Selected Lactic Acid Bacteria and Leguminosae Flours.

Aiming at meeting consumers' requirements for healthy foods, dietary needs (vegetarianism, lactose- and gluten-free), as well as the nutrition recommendations of the Health Authorities in terms of protein, fibers and bioactive compounds, the present study proposes a novel yogurt-style snack made with plant-derived ingredients. The biotechnological protocol includes the fermentation of a thermal-treated blend of cereal and legume flours by the selected lactic acid bacteria (LAB) Lactoplantibacillus plantarum DSM33326 and Levilactobacillus brevis DSM33325. The yogurt-style snack was characterized by protein and fiber concentration of 3 and 4%, respectively, and a low-fat content. Compared to the unfermented control, the yogurt-style snack was characterized by a significant higher concentration of free amino acids and lower contents of the antinutritional factors, i.e., phytic acid, condensed tannins, saponins and raffinose (up to 90%) mainly due to the LAB metabolic activity. Hence, an in-vitro protein digestibility of 79% and improvements of all the nutritional indexes related to the quality of the protein fraction (e.g., GABA) were achieved at the end of fermentation. According to the Harvard Medical School recommendations, the novel snack can be potentially classified as low-glycemic index food (53%). Antioxidant properties of the fermented snack were also improved by means of increased the total phenol content and radical scavenging activity. High survival rate of the starter LAB and a commercial probiotic (added to the snack) was found through 30 days storage under refrigerated conditions. The biotechnological protocol to make the novel snack here proposed is suitable for the large-scale application in food industry, giving a platform product with a peculiar and appreciated sensory profile.

Potential of Electrospun Poly(3-hydroxybutyrate)/Collagen Blends for Tissue Engineering Applications.

In this work, tunable nonwoven mats based on poly(3-hydroxybutyrate) (PHB) and type I collagen (Coll) were successfully produced by electrospinning. The PHB/Coll weight ratio (fixed at 100/0, 70/30, and 50/50, resp.) was found to control the morphological, thermal, mechanical, and degradation properties of the mats. Increasing collagen amounts led to larger diameters of the fibers (in the approximate range 600-900 nm), while delaying their thermal decomposition (from 245°C to 262°C). Collagen also accelerated the hydrolytic degradation of the mats upon incubation in aqueous medium at 37°C for 23 days (with final weight losses of 1%, 15%, and 23% for 100/0, 70/30, and 50/50 samples, resp.), as a result of increased mat wettability and reduced PHB crystallinity. Interestingly, 70/30 meshes were the ones displaying the lowest stiffness (~116 MPa; p < 0.05 versus 100/0 and 50/50 meshes), while 50/50 samples had an elastic modulus comparable to that of 100/0 ones (~250 MPa), likely due to enhanced physical crosslinking of the collagen chains, at least at high protein amounts. All substrates were also found to allow for good viability and proliferation of murine fibroblasts, up to 6 days of culture. Collectively, the results evidenced the potential of as-spun PHB/Coll meshes for tissue engineering applications.