Innovative Food Science & Emerging Technologies最新文献

Low-intensity pulsed electric fields (PEF) were applied to a starter culture mix (Streptococcus thermophilus, Lactobacillus bulgaricus, and partially skimmed milk) before the fermentation stage of natural yogurt. The impact of PEF processing conditions on yogurt fermentation time and quality characteristics was evaluated. PEF parameters were set based on a factorial experimental design; independent variables: electric field strength, pulse-frequency, and pulse-width, were explored, having fermentation time as a response. Most PEF treatments reduced fermentation time by 0.31–0.52 h compared to conventional yogurt processing (CY) (4.70 ± 0.23 h). The shortest time (4.18 ± 0.04 h) resulted from PEF pre-treatment with 8-μs monopolar pulses at 1 kV/cm and 150 Hz during 400 μs. The physicochemical and sensory characteristics of PEF-treated yogurt were similar to those of the CY immediately after processing and during refrigeration storage. Low-intensity PEF could be a promising alternative pre-treatment of yogurt production, reducing fermentation time while maintaining quality attributes of natural yogurt.

Industrial relevance

Conventional yogurt processing lasts around 4.5–6 h, representing high energy consumption and production costs. The application of pulsed electric fields (PEF) processing to the starter culture before yogurt fermentation represents a potential alternative to diminish production time by stimulating lactic acid bacteria and accelerating fermentation stage. This study demonstrated that low-intensity PEF (1–3 kV/ cm) reduced fermentation time by 0.31–0.52 h without compromising yogurt's quality properties, including physicochemical characteristics and sensory attributes. Obtained results suggest that this technology allows more efficient and sustainable yogurt production methods, positively impacting industry and consumers.

This study aimed to acquire a deeper knowledge of the mechanisms of PEF resistance development after the exposure of Staphylococcus aureus to sublethal alkaline and heat shocks, with a particular focus on the modifications of cell envelope properties and their impact on electroporation and its reversion. Both shocks significantly (p < 0.05) increased the surface negative charge but they barely affected surface hydrophobicity or membrane fluidity. This resulted in an increased electroporation threshold (≈ 2 kV/cm) for alkaline-shocked but not for heat-shocked cells. Heat and alkaline shock-dependent development of PEF resistance did not require de novo RNA, protein, or lipid synthesis. Addition of nisin (100 UI/mL) to the treatment medium not only counteracted the protective effect of sublethal shocks against PEF, but even increased the lethality of PEF treatments (up to 8.9-fold increase in Log cycles of inactivation) against heat-shocked and alkaline-shocked cells.

Industrial relevance

This work contributed to a deeper understanding of the mechanisms leading to the development of PEF resistance, which is essential for PEF process optimization and for the design of PEF-based combined processes for food decontamination or pasteurization.

The brewing industry produces significant volumes of spent brewer's yeast (SBY), which presents an intriguing opportunity for valorization. This study aims to optimize the extraction of various compounds of interest from electroporated SBY located both in the cytoplasm (amino acids, glutathione and proteins) and in the cell walls (mannoproteins). The optimization of the extraction time, temperature and pH, allowed obtaining an extract rich in glutathione of 2.31 ± 0.15 mg/g dw after 1 h of incubation (pH 8; 30 °C) and, a second extract rich in amino acids (155.74 ± 7.83 mg/g dw) and proteins (331.70 ± 15.64 mg/g dw) after a second incubation (37 °C, 47 h) of the biomass. To achieve comprehensive valorization of SBY, the exhausted yeast biomass was incubated with lyticase to extract mannoproteins from the cell wall. This study showcases the efficacy of a multiple response function in optimizing valuable compound extraction from electroporated SBY, aligning with circularity principles.

Tomato (Solanum lycopersicum) is a widely consumed fruit in the world. Discarded biomass has a huge potential, as tomato peel is rich in carotenoid content. This study focuses on the recovery of carotenoids from tomato industry agro-wastes, specifically peel and seeds. Initially, the conventional method was employed to analyze the sample, determining a total carotenoid content of 3.19 ± 0.23 mg β-carotene eq/g dry matter. A carotenoid profiling of the sample revealed high concentration of 5-cis-lycopene (1340.1 ± 15.6 μg all-trans-β-carotene eq/g dry matter), 9-cis lycopene (1062.7 ± 12.8 μg all-trans-β-carotene eq/g dry matter) and all-trans-β-carotene (1246.4 ± 1.7 μg all-trans-β-carotene eq/g dry matter). Microwave-assisted extraction (MAE) was employed as a green extraction method to optimize biomass-solvent ratio (BSR), extraction time (ET), and microwave power (MP) for achieving maximum recovery of carotenoids. A surface response methodology based on a Box-Behnken design was used. The optimized extract (BSR 1:10 g:mL, ET 60 s, and MP 283.84 W) was microencapsulated using maltodextrin (MD) combined with either gum arabic (GA) or whey protein isolate (WP) as wall materials. Freeze-drying was utilized for capsule sealing. The properties of the encapsulates were characterized, including moisture content (0.99 ± 0.04% for MD:GA and 0.80 ± 0.07% for MD:WP), water activity (0.087 ± 0.01 for MD:GA and 0.084 ± 0.01 for MD:WP), dissolution rate (140.4 1 ± 6.41 s for MD:GA and 86.49 ± 1.68 s for MD:WP), tapped density (0.48 ± 0.01 g/mL for MD:GA and 0.44 ± 0.01 g/mL for MD:WP), drying yield (90.73 ± 3.34% for MD:GA and 89.73 ± 3.47% for MD:WP), and encapsulation efficiency (68.12 ± 1.42% for MD:GA and 74.55 ± 1.62% for MD:WP). Bioaccessibility studies for encapsulated extract revealed values of 27.68% ± 0.72 and 25.10% ± 0.04 for MD:GA and MD: WP, respectively. This research highlights the potential of tomato agro-wastes as a valuable source of bioactive compounds. The implementation of MAE and microencapsulation techniques demonstrates effective strategies for their recovery and preservation obtaining the optimal conditions for the MAE (BSR 1:10 g: mL, ET 60 s, and MP 283.84 W) and for the encapsulation (MD: WP mixture). These findings contribute to the valorization of tomato industry by-products and their potential application in functional food products.

In this study, effects of conveyor belt catalytic infrared radiation (BCIR) baking on sensory, surface color, texture, microbial sterilization, soy isoflavone, and water distribution were investigated comprehensively. The parameters of BCIR were radiation distance (12, 15, and 18 cm), baking temperature (65 °C, 80 °C, and 95 °C), and the corresponding speed of conveyor belt (0.58, 0.41, 0.28, 0.67 m/min, etc.). Meanwhile, the effect of conventional hot air (HA) baking on dried tofu were also studied for comparison. The results showed that the impact of BCIR radiation distance on the quality of the baked dried tofu was greater than that of baking temperature. In addition, there was a correlation between the moisture indexes and quality indicators of dried tofu under different BCIR baking temperatures and radiation distances. In comparison to HA baking, BCIR was better in golden-brown level, appealing sensory, microbial safety. Meanwhile, BCIR not only shortened the total baking time but also saved energy in scaled production of baked dried tofu.

Industrial relevance

Conveyor belt catalytic infrared radiation (BCIR) baking, an emerging thermal processing technique at the pilot scale, was innovatively employed in dried tofu baking for its prompt attributes of high efficiency and energy-saving in this study. The findings of the current research explored the physicochemical qualities and water distribution subjected to BCIR treatment, with the comparison of traditional hot air baking, which can provide basis and assistance for the BCIR application in the food baking industry and for scaling up the baking process with energy-saving production.

Berries contaminated with human norovirus (HuNoV) have been frequently identified as a cause of foodborne gastroenteritis. To prevent virus transmission while preserving sensory and quality parameters, non-thermal treatments, such as high-pressure processing (HPP), can be applied to the berries and products thereof. Here, strawberry purees contaminated with HuNoV genogroup I (GI.3[P13]) and II (GII.4 Sydney [P16]), along with murine norovirus (MNV) and Tulane virus (TV) serving as surrogates, were exposed to HPP at several pressure-time combinations. Virus inactivation was assessed by cell culture, including the novel human intestinal enteroids (HIE) model for HuNoVs. The infectivity results showed TV more resistant than MNV to HPP, as also confirmed by kinetic mathematical modelling. Results indicated that a holding pressure of 450 MPa and an exposure time of ≥5 min are reliable operational conditions for HPP process to successfully control viral contamination. In addition, the inactivation models deduced from MNV and TV viruses were challenged with experimental HuNoV GII.4 infectivity resulting in bias factors <1 for all treatment conditions. This finding validates the proposed models for the conservative estimation of HuNoV inactivation. Our work offers a blueprint for moving forward with inactivation studies using the HIE system, which provides useful practical information on optimum treatments for the best public health outcomes.

Microbial and enzyme inactivation by pulsed electric field (PEF) treatment was assessed in a blended plant-based milk alternative (PBMA) containing oats and pea protein without the application of presterilization. This was conducted to investigate a novel approach that permits PEF process validation for PBMA containing heat-labile components (protein and starch). Continuous PEF processing at moderate field strengths (9–10 kV/cm) combined with mild preheating (30–45 °C) for 25 s was applied over a range of specific energy inputs (77–245 kJ/L). Selective plating permitted bacterial enumeration of inoculated surrogate organisms, despite the presence of natural microbial contaminants in the non-presterilized product. A minimum 5-log reduction of inoculated surrogates Escherichia coli and Listeria innocua alongside native microbiota was identified after preheating to 35–45 °C followed by PEF at 192–215 kJ/L. α-amylase activity was reduced by up to 89% during a similar PEF treatment (205 kJ/L, 40 °C preheating). Overall, continuous PEF combined with mild preheating temperature was shown to achieve microbial inactivation in the pea protein enriched PBMA in compliance with current food safety regulations.

Industrial relevance

Presterilization is typically applied prior to conducting microbial challenge testing on food products to validate novel pasteurization treatments according to current regulatory requirements that a minimum 5-log reduction of relevant inoculated food pathogens must be achievable. However, for a variety of blended PBMA containing heat-labile proteins, presterilization is not advisable as the occurrence of irreversible changes in the product quality linked to protein coagulation and phase separation will affect the inactivation efficacy during subsequent microbial challenge testing. Hence, an alternative approach is presented utilizing a non-presterilized PBMA and thorough microbiological analysis, combining non-selective and selective plating techniques. This allows an identification of PEF treatment parameter with a minimum 5-log reduction of inoculated surrogate organisms alongside naturally present microbial contaminants. This may serve as a valuable guideline for stakeholders in the food industry when addressing the efficacy of novel preservation treatments such as PEF in PBMA products with similar heat-induced product stability challenges.

Scallop adductors (SA) with a moisture content (MC) of 65% (H-65), 55% (H-55), 45% (H-45), and 35% (H-35) were subjected to an instant controlled pressure drop (DIC) pretreatment to investigate its influence on the subsequent heat pump drying kinetics and quality attributes. SA without DIC was performed for comparison (CK). Compared to the CK, DIC resulted in a decreasing rate of 5.88–35.29% in the drying time, but an increasing rate of 11.12–46.89% in effective moisture diffusivity coefficient depending on samples' MC. After DIC, SA showed a decrease in α-helices and β-turns, but an increase in β-sheets, and a sharp decrease in the relaxation time and proportion of the immobilized water. DIC increased total color difference (expect H-45), hardness, rehydration ratio, but decreased shrinkage rate (except H-65) compared to the CK. DIC is a promising pretreatment for intensifying drying efficiency, inhibiting volume shrinkage, and improving rehydration capacity of SA.

This study evaluated the bacterial-reducing effects of different high voltage electrostatic field (HVEF) parameters (voltage 20,25,30,35 kV, time 5,10,15,20 min) on chilled pork, and studied the effects of HVEF bacterial-reducing treatment on the microbial number and the quality of pork during ice-temperature (−1 °C) storage. The results showed that HVEF of 35 kV-15 min was the best parameter, which made a 0.51 log CFU/g bacterial reduction. HVEF treatment reduced the number of Pseudomonas spp. by 0.50 log CFU/g, but no significant decrease was found in Brochothrix thermosphacta and lactobacilli. The abundance of Pseudomonas fragi (most abundant species in pork) significantly decreased after HVEF treatment, which may be the reason for the significant decrease of TVB-N and TBARS in HVEF group at the end of storage. During −1 °C storage, HVEF group exhibited better quality characteristics on shear force and cooking loss, which could effectively extend the shelf-life of chilled pork.

Industrial relevance

High voltage electrostatic field (HVEF) is an emerging non-thermal inactivation technology. However, it is necessary to optimize the processing parameters based on the characteristics of the food. This study optimized the optimal processing parameters of HVEF for chilled pork and validated its contribution to maintaining the quality of pork during ice-temperature storage. These findings are of great significance for food processing, food preservation and the development of new refrigeration equipment.

The purpose of this study was to develop a modifying Computational Fluid Dynamics (CFD) model for precise analysis of surimi extrusion behavior and establish a machine learning method for quickly prediction of surimi printability. The 2D rotational axisymmetric model used in this study to replace the 3D/4D physical model, which could improve the simulation efficiency. To improve the accuracy of the CFD simulations, the wall “no-slip” boundary condition assumed in the textbook was replaced with a boundary condition of wall slip. This reduced the error between the simulated results and the measured ones to <1%, and thus calculated required extrusion pressure below 17,034 Pa for printability. The CFD calculation efficiency was improved 33 times than the previously reports by the modifying CFD model, and the simulated results for the required extrusion pressure of inks could be obtained within 10 s. Additionally, a machine-learning method (partial least squares regression model) based on texture data was proposed to quickly predict the required extrusion pressure of surimi to assessed printability. The machine learning model showed a good performance with an R² > 0.95.