https://hdl.handle.net/10259/4245 2026-07-30T16:13:34Z https://hdl.handle.net/10259/11954 Cascade Valorization of Okara by Subcritical Water Hydrolysis: Assessment of Protein and Amino Acid Profile in Batch and Semi-Continuous Systems Barea Gómez, Pedro; Illera Gigante, Alba Ester; Candela Gil, Helena; Melgosa Gómez, Rodrigo; Benito Román, Oscar; Sanz Díez, Mª Teresa This study assesses subcritical water hydrolysis (SWH) as a sustainable approach for protein recovery from okara, following isoflavone valorization. The initial extract, obtained at 120 °C, contained over 1200 µg of isoflavones per gram of dry okara. The solid residue underwent a second protein extraction step in both batch and semi-continuous modes. The batch extraction was conducted at 180 °C for 3 h at 5 MPa in a 0.5 L reactor. Under these conditions, total amino acid recovery reached 81 ± 3% (12.6 g/L), with 20 ± 1% of free amino acids, mainly glutamic acid, and a favorable profile of essential amino acids. These results were comparable to protein extraction from untreated okara, indicating that the prior isoflavone extraction did not hinder protein hydrolysis, but rather contributed positively within the cascade framework. Hydrolysis was also performed in a semi-continuous mode in a 2.3 L reactor, with a residence time of 2.75 min, in a two-stage temperature process (180 °C and 270 °C). The second stage yielded a significantly higher extraction than the first one, achieving a total 70.4% protein recovery (1.22 g/L) with 10% of free amino acids, with glutamic acid as the dominant one. Carbohydrate analysis revealed high hydrolysis yields for galactans, arabinans, and xylans, but these exhibited lower thermal stability compared to proteins. Okara emerges as a promising by-product for a bio-cascade process, combining a mild first stage for isoflavone extraction with a more severe second stage for protein extraction/hydrolysis. 2026-05-01T00:00:00Z https://hdl.handle.net/10259/11350 High voltage atmospheric cold plasma technology as a food safety intervention for decontamination of cutting tools during ready-to-eat poultry meat slicing Souza, Vanessa Rios de; Illera Gigante, Alba Ester; Keener, Kevin M. This study aimed to build a prototype that integrates a cold plasma capability into a manual meat slicer while it is in operation to minimize cross-contamination from the circular cutting blade. A high voltage atmospheric cold plasma (HVACP) generator was attached to a meat slicer with a rotating 22.5-cm diameter stainless steel slicing blade. The meat slicer with the installed cold plasma generator was contained within a sealed, clear acrylic box. Listeria innocua (LI) was selected as the test organism, and initial testing was performed on stainless-steel coupons in room air at a relative humidity ranging from 30 to 90% for treatment times up to 240 s. Results found that 240 s and 90% RH showed a 3.0-log reduction of LI. These conditions were then replicated using “dirty” stainless-steel knife while rotating. The results showed only a 0.5-log LI reduction. The gas was changed from air to MA65 gas blend (65% O2, 30% CO2 and 5% N2) and then a 1.91 log LI reduction was achieved on the “dirty” knife. Industrial relevance Due to the rapid processing speeds required in the food industry, it is difficult to assure the complete cleanliness of the tools and surfaces used at all times, and then, operations like the cutting /slicing step are still one of the critical points for cross-contamination during meat processing. High voltage atmospheric cold plasma (HVACP) is a practical intervention that has the potential to deliver a continuous, in-situ decontamination of the knife during operation to mitigate the risk of cross-contamination. The developed prototype, as shown in this study, can deliver beneficial results in short treatment time and with minimal inputs of air and electricity, without heating effects, minimizing the use of water, or the use of sanitizers. 2022-08-01T00:00:00Z https://hdl.handle.net/10259/11349 Enzyme inactivation and changes in the properties of cloudy apple juice after high‐pressure carbon dioxide and thermosonication treatments and during refrigerated storage Illera Gigante, Alba Ester; Beltrán Calvo, Sagrario; Sanz Díez, Mª Teresa High-pressure carbon dioxide and thermosonication technologies were applied to cloudy apple juice to determine their effect on polyphenol oxidase (PPO) and pectin methylesterase (PME) activity and other quality parameters right after the treatment and during storage at 4ºC for 28 days. Treatment conditions were 20 MPa, 45ºC, for 60 min and 20 kHz, 62ºC, 100% amplitude for 20 min, for pressurized CO2 and thermosonication treatments, respectively. Both treatments showed a great impact on PPO activity and its residual activity steadily decreased during storage at 4ºC. In contrast, PME was found to be more resistant to the treatments. After both treatments, a homogenization effect was observed, which was also reflected in an increase in the cloud value of the juices after the treatments, kept during storage. Antioxidant capacity and total polyphenol content kept high levels during storage after both treatments. 2020-07-01T00:00:00Z https://hdl.handle.net/10259/11151 New approach using alternative proteolytic enzymes to the conventional enzyme pronase for the isolation of bread melanoidins Cavia Saiz, Mónica; Gerardi, Gisela; Muñiz Rodríguez, Pilar; García Tojal, Javier; Salazar Mardones, Gonzalo Bread melanoidins are melanoproteins classically extracted with the proteolytic enzyme pronase E (S. griserus). In this study, the structure and functionality of melanoidins extracted with the proteolytic enzymes papain (PE) and enzymes from B. subtillus (SP) and a mixture from B. subtillus and A. oryzae (MP) were evaluated. PE extracted melanoidins have the highest nitrogen (4.3 %) and protein (29 %) content. FTIR showed that PE had a higher protein content and pronase had higher in carbohydrates. The K420 and K345 values and antioxidant capacities of the PE extract were similar to pronase and higher than the other microbial enzymes. After in vitro digestion, the increased in the antioxidant capacity was most pronounced in the PE extract. No neurotoxicity was observed, as evidenced by no neuronal cell death or changes in neuronal ROS levels. These results indicate that the PE enzyme may be a good alternative to pronase for extraction of melanoidins. 2025-06-01T00:00:00Z