Ivanildo José da Silva Junior

The valorization of agro-industrial residues represents a strategic approach to advancing sustainability and circular bioeconomy principles in the food sector. Although bacterial cellulose (BC) production from waste substrates has been widely explored, limited attention has been given to the role of nitrogen source modulation in complex fermentation systems. This study evaluated passion fruit peel hydrolysate (PFPH), a cellulose- and hemicellulose-rich by-product, as an alternative carbon source for BC production using a symbiotic culture of bacteria and yeast (SCOBY) under static conditions. Acid hydrolysis and detoxification were performed to obtain fermentable sugars while minimizing inhibitory compounds. Different nitrogen sources and purification strategies were comparatively assessed. The highest purified BC yield (81 g L⁻¹ of culture medium) was obtained using ammonium sulfate, whereas sodium nitrate promoted greater impurity removal (77.51% mass reduction). Structural and chemical analyses (FTIR, XPS, and XRD) confirmed effective delignification, enhanced surface purity, and increased crystallinity. SEM revealed a homogeneous nanofibrillar network, and thermogravimetric analysis indicated thermal stability up to approximately 300 °C. Soil burial assays showed 26% mass loss after 42 days, demonstrating controlled biodegradation consistent with food packaging requirements. Overall, PFPH proved to be an efficient and sustainable substrate for BC biosynthesis. The modulation of nitrogen source significantly influenced both production yield and structural properties, highlighting the potential of this system for developing environmentally responsible biopolymer materials for food packaging applications.

Alcalase was immobilized–stabilized on carrageenan beads following a previously described protocol. Then, the activities of free and immobilized enzymes were compared using different protein substrates (casein, (CS), bovine serum albumin (BSA), or hemoglobin (HG)) at different pH values and temperatures. The observed activity depended on the substrate protein and enzyme formulation used. The highest enzyme activity could be observed at pHs 5, 7, or 10, depending on the substrate protein and the Alcalase formulation. The effect of the temperature at these pHs on the activity versus the different substrate proteins showed a common pattern. At low temperatures, the immobilized enzyme presented higher (mainly at acidic-neutral pH values and using BSA) or similar specific activity than the free enzyme. At temperatures near the optimal for the free enzyme, it became the most active, while at higher temperatures, the immobilized enzyme recovered the lead, although differences in the optimal temperature were not very significant. This may be explained by the lower mobility of the immobilized–stabilized enzyme. The immobilized enzyme could be much more active than the free enzyme or slightly less active, even using mild conditions, depending on the substrate protein, pH, and temperature used to determine the enzyme activity.

Summary: Açai, a fruit typical of Amazonia in Brazil, is consumed due to beneficial health effects. Aqueous two‐phase systems (ATPS) based on ethanol (28% w/w) and ammonium sulfate (17.5% w/w) were employed in the partitioning of anthocyanins from açai. Experiments, applying 50 mL equilibrium cells and a 1‐L glass vessel reactor, evaluated anthocyanin partition feasibility on a laboratory scale‐up. The anthocyanin preferentially moved to the top (ethanol‐rich phase) and sugars to the bottom (ammonium sulfate‐rich phase). Scale‐up effects were compared with the equilibrium cell experiments with anthocyanin extraction yielding more than 64% w/w, the yield of sugars in the bottom phase (>61% w/w) and removal of sugars (97%), showing the feasibility for the scale‐up process. The anthocyanin profile from açai, ATPS partition on the bench scale and laboratory scale‐up evaluated by UPLC‐QTOF‐MS identified cyanidin, peonidin and pelargonidin derivatives.

As the rind of passion fruit is rich in flavonoids, it can be used as an alternative to obtain these compounds. This study extracted flavonoids from passion fruit rinds by pressurized solvent extraction. The obtained extract was submitted to aqueous two-phase extraction formed by ethanol and salts for the recovery of flavonoids. Passion fruit rind (PFR) was submitted to pressurized solvent extraction (PSE) using ethanol/water solution at 60:40 (v/v) as a solvent for the extraction of bioactive compounds, showing a polyphenol content of 5.48 gGAE∙kg^− 1 PFR. Then, aqueous two-phase systems (ATPS) showed that flavonoids and sugars partitioned into opposite phases. The recovery of flavonoids in the top phase was above 98% w/w, and the recovery of sugars in the bottom phase was above 97% w/w. LC‒MS was used to evaluate the flavonoid profile in the top phase of ATPS, and the major flavonoids detected were lucenin-2, vicenin, isoorientin, apigenin, schaftoside and vitexin. According to the flavonoid profile by LC‒MS and the values of recovery of flavonoids, ATPS proved to be an effective technique for recovery of flavonoids from PSE extraction.

Xylitol is a polyol with sweetening and anti‐cariogenic properties and is highly relevant to the food and pharmaceutical industries. This work evaluates xylitol production by three yeasts (Candida tropicalis, Kluyveromyces marxianus CCA510, and Kluyveromyces marxianus ATCC 36907) from different carbon sources: D‐xylose (medium xylose [MX]) and D‐xylose plus D‐glucose (medium xylose and glucose [MXG]). The potential of xylitol production from hemicellulose hydrolysate of cashew bagasse was evaluated. In MX medium, K. marxianus CCA510 was the strain that produced higher xylitol concentration (17.04 g · L⁻¹). However, K. marxianus ATCC 36907 and C. tropicalis produced 13.22 and 9.54 g · L⁻¹, respectively. On the other hand, in MXG medium, probably due to the presence of glucose as a carbon source, lower xylitol production was observed for all microorganisms: the CCA510 strain produced 13.30 g · L⁻¹ of xylitol, while C. tropicalis and ATCC 36907 produced 11.42 and 0.64 g · L⁻¹, respectively. Additionally, the production of ethanol as a secondary product was also noted. According to the results of the kinetic study, xylitol formation is associated with the growth and consumption of substrate (xylose), which is a typical behaviour of a primary metabolite for the three yeasts. Furthermore, the strain K. marxianus CCA510 was able to produce xylitol from cashew apple bagasse hydrolysate (CABH), evidencing its potential for use in bioprocesses related to biorefinery. In view of the results reported here, it was possible to clarify in detail the kinetics of xylitol production by the yeast strains evaluated, which had the ability to produce xylitol from CABH, providing added value to this agro‐industrial residue.

Anthocyanins obtained from jambolan have been used as active agents in different carboxymethyl starch-based tablet formulations and their release profiles evaluated in simulated gastric fluids (SGF) and simulated intestinal (SIF) fluids. Structural analysis highlighted a strong interaction between anthocyanins and carboxymethyl starch, evidenced by scanning electron microscopy and infrared analysis. Tablet dissolution behavior varied according to the pH of the media, being controlled by the swelling and/or erosion of the polymeric matrix. Various formulations for immediate, fast, and sustained release of anthocyanins for 30 min, 2 h and 12 h of dissolution have been developed. It was found that monolithic carboxymethyl starch tablets loaded with powdered jambolan extract efficiently afforded the complete delivery (100% of anthocyanins) to different sites of the simulated gastrointestinal tract and ensured the stability of these pigments, which maintained their antioxidant activity.