In the present study, cold atmospheric plasma (CAP) was employed as a pretreatment method for the extraction of phenolic compounds from spent coffee grounds (SCGs). The impact of CAP treatment conditions, i.e., thickness of the SCGs layer (mm), distance between the plasma source and the SCGs layer (mm) and duration of CAP treatment (min), on the total phenol content, in vitro antioxidant activity, as well as caffeine and chlorogenic acid content of SCGs, was investigated. The process parameters were optimized with the aid of response surface methodology (RSM). After optimizing the CAP pretreatment conditions, the CAP-treated SCGs were subjected to ultrasound-assisted extraction using ethanol as the extraction solvent. The optimum conditions for CAP treatment identified, i.e., thickness, 1 mm; distance, 16 mm; and duration, 15 min, led to a significant enhancement in the recovery of bioactive compounds from SCGs compared to those obtained from untreated SCGs. Total phenolic content and antioxidant activity significantly increased (i.e., TPC from 19.0 ± 0.7 to 24.9 ± 1.4 mg GAE/100 g dry SCGs, A_DPPH from 106.7 ± 5.01 to 112.3 ± 4.3 μmol Trolox/100 g dry SCGs, A_ABTS from 106.7 ± 5.01 to 197.6 ± 5.8 μmol Trolox/100 g dry SCGs, A_CUPRAC from 17938 ± 157 to 18299 ± 615 μmol Trolox/100 g dry SCGs). A significant increase in caffeine content from 799.1 ± 65.1 mg to 1064 ± 25 mg/100 g dry SCGs and chlorogenic acid content from 79.7 ± 15.3 mg to 111.3 ± 3.3 mg/100 g dry SCGs, was also observed. Overall, CAP pre-treatment can be used to enhance the recovery of bioactive compounds from SCGs.

Cold atmospheric plasma (CAP) is a novel non-thermal technology with significant potential for use in meat processing to prolong shelf life. The objective of the study was to evaluate the efficiency of CAP treatment on the natural microbiota and quality traits of pork stored for 8 days at 4 °C. CAP treatment was applied by employing piezoelectric direct discharge technology to treat pork samples for 0, 3, 6, and 9 min. Reductions of approximately 0.8–1.7 log CFU/g were observed in total viable counts (TVC) and Pseudomonas spp. levels for CAP treatments longer than 3 min, immediately after treatment. A storage study revealed that CAP-treated pork (>6 min) had significantly lower levels of TVC, Pseudomonas spp., and Enterobacteriaceae throughout storage. Regarding quality traits, CAP application for longer than 3 min significantly increased water retention and yellowness and decreased meat redness compared to untreated pork. However, other parameters such as pH, tenderness, and lightness exhibited no statistically significant differences between untreated and CAP-treated pork. Lipid oxidation levels were higher only for the 9-min treatment compared to untreated pork. Our results revealed that CAP is a promising technology that can extend the microbiological shelf life of pork during refrigeration storage.

In the context of the circular economy, the valorization of bio-derived waste has become a priority across various production sectors, including food processing and packaging. Gelatin (Gel), a protein which can be recovered from meat industry byproducts, offers a sustainable solution in this regard. In this study, pork-derived gelatin was used to develop novel edible active packaging films, designed for meat products. Glycerol (Gl) was used as a plasticizer. Two types of montmorillonite-based nanohybrids were employed as both reinforcing agents and carriers of antioxidant/antibacterial compounds: eugenol-functionalized montmorillonite (EG@Mt) and citral-functionalized montmorillonite (CT@Mt). The active films were formulated as Gel/Gl/xEG@Mt and Gel/Gl/xCT@Mt, where x = 5, 10, or 15 wt.%. Controlled-release kinetics showed that EG@Mt released up to 95% of its adsorbed eugenol, whereas CT@Mt released up to 55% of its adsorbed citral. The films were evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and tested for antibacterial activity against Escherichia coli and Listeria monocytogenes. Results demonstrated that the Gel/Gl/xEG@Mt films exhibited superior antioxidant and antibacterial performance compared to the Gel/Gl/xCT@Mt films. All formulations were impermeable to oxygen. Although the incorporation of EG and CT slightly reduced cell viability, values remained above 80%, indicating non-toxicity. In conclusion, the film containing 15 wt.% EG@Mt achieved an oxygen transmission rate of zero, an effective concentration (EC₆₀) of 9.9 mg/L to reach 60% antioxidant activity, and reduced E. coli and L. monocytogenes populations by at least 5.8 log CFU/mL (p < 0.05), bringing them below the detection limit. Moreover, it successfully extended the shelf life of fresh minced pork by two days.

The growing demand for sustainable food packaging has driven the development of active packaging systems using biopolymers like poly(lactic acid) (PLA) and natural antimicrobials. This study focuses on creating novel nanohybrids by loading carvacrol (CV) and trans-cinnamaldehyde (tCN) onto ZnO nanorods for incorporation into PLA/triethyl citrate (TEC) films. The CV@ZnO and tCN@ZnO nanohybrids were synthesized and characterized using XRD, FTIR, desorption kinetics, and by assessing their antioxidant and antibacterial properties. These nanohybrids were then integrated into PLA/TEC films via extrusion. The resulting active films were evaluated for their physicochemical, mechanical, barrier, antioxidant, and antibacterial properties. The tCN@ZnO nanohybrid exhibited a stronger interaction with the ZnO surface and a slower release rate compared to CV@ZnO. While this strong interaction limited its direct antioxidant activity, it proved highly beneficial for the final film’s performance. Films containing 10% tCN@ZnO demonstrated the strongest antibacterial efficacy in vitro against Listeria monocytogenes and Escherichia coli and functioned as potent mechanical reinforcement fillers. Crucially, in a practical application, the PLA/TEC/10tCN@ZnO film significantly extended the shelf-life of fresh minced pork during 6 days of refrigerated storage. It effectively suppressed microbial growth (TVC), delayed lipid oxidation (lower TBARS values), and preserved the meat’s colour and nutritional quality (higher heme iron content) compared to control packaging. The developed tCN@ZnO nanohybrid is confirmed to be a highly effective active agent for creating PLA/TEC-based packaging that can enhance the preservation of perishable foods.

In this study, aligned with the principles of the circular economy and sustainability, novel eugenol@natural zeolite (EG@NZ) and citral@natural zeolite (CT@NZ) nanohybrids were developed. These nanohybrids were successfully incorporated into a pork gelatin (Gel)/glycerol (Gl) composite matrix using an extrusion–compression molding method to produce innovative active packaging films: Gel/Gl/xEG@NZ (where x = 5, 10, and 15%wt.) and Gel/Gl/xCT@NZ (where x = 5 and 10%wt.). All films exhibited zero oxygen barrier properties. Release kinetic studies showed that both EG@NZ and CT@NZ nanohybrids adsorbed up to 58%wt. of their respective active compounds. However, EG@NZ exhibited a slow and nearly complete release of eugenol, whereas CT@NZ released approximately half of its citral content at a faster rate. Consequently, the obtained Gel/Gl/xEG@NZ films demonstrated significantly higher antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazylradical (DPPH) assay and superior antibacterial effectiveness against Escherichia coli and Listeria monocytogenes compared to their CT-based counterparts. Overall, the Gel/Gl/xEG@NZ films show strong potential for applications as active pads for fresh pork ham slices, offering zero oxygen permeability, enhanced antioxidant and antibacterial properties, and effective control of total viable count (TVC) growth, maintaining a low and steady rate beyond the 10th day of a 26-day storage period.

In this study aligned with the principles of the circular economy and sustainability, novel eugenol@natural zeolite (EG@NZ) and citral@natural zeolite (CT@NZ) nanohybrids were developed. These nanohybrids were successfully incorporated into a pork gelatin (Gel)/glycerol (Gl) composite matrix using an extrusion molding-compression method to develop produce innovative active packaging films: Gel/Gl/xEG@NZ (where x = 5, 10, and 15 %wt.) and Gel/Gl/xCT@NZ (where x = 5 and 10 %wt.). All films exhibited zero oxygen barrier properties. Release kinetic studies showed that both EG@NZ, and CT@NZ nanohybrids adsorbed up to 58 %wt. of their respective active compounds. However, EG@NZ exhibited a slow and nearly complete release of eugenol, whereas CT@NZ released approximately half of its citral content at a faster rate. Consequently, the obtained Gel/Gl/xEG@NZ films demonstrated significantly higher antioxidant activity as measured by the 2,2-Diphenyl-1-picrylhydrazylradical (DPPH) assay, and superior antibacterial effectiveness against Escherichia coli and Listeria monocytogenes compared to their CT-based counterparts. Overall, the Gel/Gl/xEG@NZ films show strong potential for applications as active pads for fresh pork ham slices, offering zero oxygen permeability, enhanced antioxidant and antibacterial properties and effective control of total viable count(TVC) growth, maintaining a low and steady rate beyond the 10th day of a 26-day storage period.