Kinetic modeling of inactivation of natural microbiota and Escherichia coli on cherry tomato treated with fixed multi-frequency sonication

Tuning the Dynamic Reaction Balance of CRISPR/Cas12a and RPA in One Pot: A Key to Switch Nucleic Acid Quantification

Excavating nucleic acid quantitative capabilities by combining clustered regularly interspaced short palindromic repeats (CRISPR) and isothermal amplification in one pot is of common interest. However, the mutual interference between CRISPR cleavage and isothermal amplification is the primary obstacle to quantitative detection. Though several works have demonstrated enhanced detection sensitivity by reducing the inhibition of CRISPR on amplification in one pot, few paid attention to the amplification process and even dynamic reaction processes between the two. Herein, we find that DNA quantification can be realized by regulating either recombinase polymerase amplification (RPA) efficiency or CRISPR/Cas12a cleaving efficiency (namely, tuning the dynamic reaction balance) in one pot. The sensitive quantification is realized by utilizing dual PAM-free crRNAs for CRISPR/Cas12a recognition. The varied RPA primer concentration with stabilized CRISPR systems significantly affects the amplification efficiency and quantitative performances. Alternatively, quantitative detection can also be achieved by stabilizing the amplification process while regulating the CRISPR/Cas12a concentration. The quantitative capability is proved by detecting DNA targets from Lactobacillus acetotolerans and SARS-CoV-2. The quantitative performance toward real samples is comparable to quantitative real-time PCR for detecting L. acetotolerans spiked in fermented food samples and SARS-CoV-2 clinical samples. We expect that the presented method will be a powerful tool for quantifying other nucleic acid targets.

Modeling of the inactivation kinetics of aerobic mesophiles and yeasts and molds natural microbiota in nonthermal plasma-treated pineapple (Ananas comosus) juice

The nonthermal plasma (NTP) technology is a promising nonthermal technology that can be employed for pasteurization of fruit juice. The effect of NTP on the natural microbiota, namely, aerobic mesophiles (AM), and yeasts and molds (YM) in pineapple juice were examined in the experimental range of 25-45 kV up to 10 min treatment time. At an applied voltage of 45 kV, the AM and YM count reductions of 4.7 and 4.1 log cfu/mL were obtained at the end of the 14-min treatment. The inactivation kinetics of microbes were attempted to be explained using nonlinear models, including Weibull + tail, Geeraerd, log-logistic, Coroller, and Cerf. The residual population (Nres ) model parameter in the Geeraerd model explained the tailing behavior of microbes. Furthermore, the estimated values for the scale parameter and destruction rate constants were used to describe the sensitive and resistant percentages of the microbial population. According to statistical parameters (R2 : 0.978-0.999, RMSE: 0.034-0.277) and validation indicators (accuracy factor: 1.013-1.152, bias factor: 0.985-1.12), all models performed well. Akaike's theory was used to select the best-fit model, and the Coroller model was shown to be the most accurate one for AM and YM, exhibiting the lowest Akaike increment (Δi  = 0). PRACTICAL APPLICATION: Nonthermal plasma may be used as an alternate nonthermal process for this product in order to meet customer appeal for safe and nutritious juice with minimal processing. The goal of this work was to produce a nutritious and safe pineapple juice by using nonthermal processing.

Modelling of inactivation kinetics of Escherichia coli, Salmonella Enteritidis and Bacillus subtilis treated with a multi-hollow surface dielectric barrier discharge plasma

The efficacy of multi-hollow surface dielectric barrier discharge treatment against Escherichia coli, Salmonella Enteritidis and Bacillus subtilis was studied. Ambient air, O2, and N2 were used as working gas with a flow rate of 6 l/m. Power delivered into plasma was 30 W over an area of 2 × 2 cm2. The active species in plasma generated in different gases participating in the inactivation of microorganisms were evaluated by optical emission spectroscopy and Fourier transform infrared spectroscopy. Inactivation curves were fitted to the Bigelow log-linear, the biphasic, and Geeraerd models. According to the results, all plasma treatments inactivated tested microorganisms, depending on a working gas. The most sensitivity of bacteria was observed to the ambient air plasma. Inactivation up to 5 log for E. coli and S. Enteritidis could be achieved within 15 s of plasma treatment. Air plasma exposure of 25 s also led to log10 CFU/ml of B. subtilis from 7.98 to 4.39. S. Enteritidis was slight resistance to plasma treatment with N2. Within 180 s nitrogen plasma treatment, a 2.04 log10 CFU/ml reduction was recorded.

Modeling of Listeria innocua, Escherichia coli, and Salmonella Enteritidis inactivation in milk treated by gamma irradiation

Measuring microbial inactivation in food is useful for food technology as it allows for predicting the growth or death of microorganisms. This study aimed to investigate the effect of gamma irradiation on the lethality of microorganisms inoculated in milk, estimate the mathematical model of inactivation of each microorganism, and evaluate kinetic indices to determine the efficient dose in the treatment of milk. Raw milk samples were inoculated with cultures of Salmonella enterica subsp. enterica serovar Enteritidis (ATCC 13076), Escherichia coli (ATCC 8739), and Listeria innocua (ATCC 3309), irradiated at doses of 0, 0.5, 1, 1.5, 2, 2.5, and 3 kGy. The fitting of the models to the microbial inactivation data was performed using the GinaFIT software. The results demonstrated a significant effect of irradiation doses on the population of microorganisms, with the application of a dose of 3 kGy, a reduction of approximately 6 logarithmic cycles is observed for L. innocua and 5 for S. Enteritidis and E. coli. The model with the best fit was different for each microorganism studied: for L. innocua, the model was log-linear + shoulder; for S. Enteritidis and E. coli, the model that showed the best fit was the biphasic. The studied model fitted well (R2 ≥ 0.9; R2 adj. ≥ 0.9 and smallest RMSE values) for the inactivation kinetics. The lethality of the treatment, considering a reduction in the 4D value, was achieved with the predicted dose of doses of ±2.22, ±2.10, and ±1.77 kGy, for L. innocua, S. Enteritidis, and E. coli, respectively.

Use of Ultrasonic Cleaning Technology in the Whole Process of Fruit and Vegetable Processing

In an era of rapid technological development, ultrasound technology is being used in a wide range of industries. The use of ultrasound technology in fruit and vegetable processing to improve production efficiency and product quality has been an important research topic. The cleaning of whole fresh fruits and vegetables is an important part of fruit and vegetable processing. This paper discusses the development process of components of the ultrasonic equipment, the application of ultrasonic technology in fruit and vegetable cleaning, and the research advances in ultrasonic cleaning technology. Moreover, the feasibility of ultrasonication of fruits and vegetables for cleaning from the perspectives of microbial inactivation, commodity storage, and sensory analysis were discussed. Finally, the paper identified the inevitable disadvantages of cavitation noise, erosion, and tissue damage in fruit and vegetable processing and points out the future directions of ultrasonic fruit and vegetable cleaning technology.

Multi-frequency ultrasound:A potential method to improve the effects of surface decontamination and structural characteristics on large yellow croaker (Pseudosciaena crocea) during refrigerated storage

The effects of multi-frequency ultrasound on surface decontamination and structural characteristics of large yellow croaker (Pseudosciaena crocea) during refrigerated storage were evaluated. The results of total viable counts (TVCs) and psychrophilic bacteria counts (PBCs) demonstrated that multi-frequency ultrasound retarded the growth of microorganisms. The bacteriostatic effect was positively correlated with the increase of ultrasound frequencies. However, compared with triple-frequency ultrasound (TUS, 20/28/40 kHz) treatment, dual-frequency ultrasound (DUS, 20/28 kHz) treatment had higher water-holding capacity (WHC) and immobilized water content, better texture characteristics, lower pH and total volatile basic nitrogen (TVB-N). Through the results of myofibrillar fragmentation index (MFI), intrinsic fluorescence intensity (IFI) and atomic force microscope (AFM), multi-frequency ultrasound could effectively stabilize the myofibrillar protein structure of refrigerated large yellow croaker, which could maintain better texture characteristics. The effects of DUS were the most significant. Therefore, multi-frequency ultrasound treatment could inhibit the growth of microorganisms and improve the structural characteristics of large yellow croaker during refrigerated storage.

Osmotic, osmovacuum, sonication, and osmosonication pretreatment on the infrared drying of Ginkgo seed slices: Mass transfer, mathematical modeling, drying, and rehydration kinetics and energy consumption

This study evaluated the mass transfer, drying, and rehydration kinetics (drying and rehydration curve, moisture diffusivity [D_eff ]), energy consumption (specific energy consumption [SEC], moisture extraction rate (MER), and specific moisture extraction rate [SMER]), and mathematical modeling of infrared dried Ginkgo biloba seed (GBS) using the various nonthermal pretreatments namely: osmotic (OS), osmovacuum (V + OS), ultrasound (US, ginkgo seed immersed in a distilled water with US), and osmosonication (US + OS, ginkgo seeds immersed in an OS solution with US). Results showed that various pretreatments affected mass transfer, drying, and rehydration characteristics, and energy consumption, which was confirmed by principal component analysis. In terms of mass transfer, US pretreatment recorded the highest weight loss while the osmosonication pretreatment registered the highest solid gain. The entire drying process occurred in the falling-rate period. The D_eff values were within the normal range of agroproducts (10^-11 to 10^-8 m² /s). The modified Page-I and Weibull model best fitted the drying and rehydration kinetics, respectively, with the coefficient of determination (R² ) > 0.991, root mean square error, residual sum of squares, and reduced chi-square closer to zero, compared with the other models. The untreated GBS (control) had the lowest energy efficiency (lowest SMER and MER) and the highest SEC than the pretreated GBS. Among the various pretreatments, the US pretreatment of GBS was superior, with the highest D_eff , MER, SMER, and drying rate, and lowest drying time and SEC. Based on the findings, sequential US pretreatment and infrared drying is a feasible drying technique for GBS that could be used commercially. PRACTICAL APPLICATION: Ginkgo tree cultivation in China has exceeded market needs with 60,000 tons per annum of GBS produced. Hence, there is a compelling need to explore new chances to use GBS availability irrespective of the seasonality and address the problem where GBS utilization is limited to the early phases of home-cooked dishes. Although drying increases the shelf life of ginkgo seeds, there is a higher operation cost. Thus, pretreatment can reduce energy consumption and augment the product quality is ideal. This research reported the impact of nonthermal pretreatments on ginkgo seeds' mass transfer, drying, and rehydration characteristics. The present results will provide a comprehensive understanding of the engineering application of ginkgo seed pretreatment, allowing for the best technique to be selected.

Mathematical modeling of nutritional, color, texture, and microbial activity changes in fruit and vegetables during drying: A critical review

Retention of quality attributes during drying of fruit and vegetables is a prime concern since the product's acceptability depends on the overall quality; particularly on the nutritional, color, and physical attributes. However, these quality parameters deteriorate during drying. Food quality changes are strongly related to the drying conditions and researchers have attempted to develop mathematical models to understand these relationships. A better insight toward the degradation of quality attributes is crucial for making real predictions and minimizing the quality deterioration. The previous empirical quality models employed kinetic modeling approaches to describe the quality changes and therefore, lack the realistic understanding of fundamental transport mechanisms. In order to develop a physics based mathematical model for the prediction of quality changes during drying, an in-depth understanding of research progress made toward this direction is indispensable. Therefore, the main goal of this paper is to present a critical review of the mathematical models developed and applied to describe the degradation kinetics of nutritional, color, and texture attributes during drying of fruit and vegetables and microbial growth model during storage. This review also presents the advantages and drawbacks of the existing models along with their industrial relevance. Finally, future research propositions toward developing physics-based mathematical model are presented.

Effects of low frequency multi-mode ultrasound and it's washing solution's interface properties on freshly cut cauliflower

This study investigated the effect of single and dual frequency ultrasound washing on freshly cut cauliflower, by pulsed and sweep frequency modes, with or without the addition of zinc acetate (ZA), tea saponin (TS) and ethanol (ET). Results showed that the surface microorganisms were efficiently decreased by sweep dual frequency ultrasound washing. Moreover, the use of 0.5% ZA, or 0.06% TS or 5% ET as washing solution improved the bacterial reduction efficiency. Reducing the interfacial tension, viscosity and contact angle of washing solution may strengthen ultrasound cavitation. Nearly 2.0 log CFU/g natural microorganisms were decreased, and shelf life was extended from 2 to 4-8 days under 4 °C. Physicochemical parameters of bioactive compounds content, enzyme activity, antioxidant ability, freshness were analyzed. Results showed that 0.5% ZA as washing solution of ultrasound washing was beneficial to the quality maintenance during storage period.

Ohmic heating processing of milk for probiotic fermented milk production: Survival kinetics of Listeria monocytogenes as contaminant post-fermentation, bioactive compounds retention and sensory acceptance

The survival kinetics of Listeria monocytogenes (9 log CFU/mL) as a post-fermentation contaminant in probiotic fermented milk (Lactobacillus acidophilus La-5, 8-9 log CFU/mL) processed with milk subjected to ohmic heating (0, 4, 6, and 8 V/cm; CONV, OH₄, OH₆, OH₈, 90-95 °C/5 min) was investigated using Weibull predictive model. Additionally, the presence of bioactive compounds (antioxidant activity, inhibition of the enzymes α-glucosidase, α-amylase, and angiotensin-converting) and sensory analysis (consumer test) of probiotic fermented milks were evaluated. Overall, OH provided a decrease in the viability of Listeria monocytogenes, suitable Lactobacillus acidophilus counts, and satisfactory results in the gastrointestinal tract survival. The Weibull model presented an excellent fit to the data of all conditions. Furthermore, lower δ values (217-298 against 665 h, CONV), and increased R² values (0.99 against 0.98, CONV) were obtained for the OH-treated samples, emphasizing the best performance of OH data. In addition, OH improved the generation of bioactive compounds as well as the sensory acceptance. Indeed, considering functional and safety purposes, OH presented as an interesting technology to be used in milk for manufacturing probiotic fermented milk.

Influence of ultrasound on selected microorganisms, chemical and structural changes in fresh tomato juice

The paper presents the possibility of applying ultrasonic technology for inactivation of mesophilic aerobic microorganisms, lactic acid bacteria, coliform bacteria, and yeast with the maintenance of the chemical and structural properties of tomato juice. The research was conducted on fresh tomato juice obtained from the Apis F₁ variety. Pressed juice was exposed to high power ultrasound and frequency 20 kHz with three operational parameters: ultrasound intensity (28 and 40 W cm⁻²), treatment time (2, 5, and 10 min), and product storage time (1, 4, 7 and 10 days). The temperature of the juice during the sonication ranged from 37 to 52 °C depending on the intensity of ultrasound and time of treatment. Effectiveness of the tested microorganisms eradication in the juice depended on the amplitude and duration of the ultrasound treatment. It was shown that the juice exposed to an ultrasonic field with an intensity of 40 W cm⁻² for 10 min was microbiologically pure and free from spoilage microorganism even after 10 storage days. No statistically significant differences in pH were found between the untreated juice and the sonicated samples. The ultrasonic treatment was found to change the content of lycopene in small degree (both an increase and a decrease, depending on the processing time) and to induce a small decrease in the vitamin C content. The study suggests that the ultrasonic treatment can be successfully implemented on an industrial scale for the production of not-from-concentrate (NFC) tomato juice.

Nondestructive monitoring, kinetics and antimicrobial properties of ultrasound technology applied for surface decontamination of bacterial foodborne pathogen in pork

In this study, electronic nose (E-nose) and Hyperspectral Imaging (HSI) was employed for nondestructive monitoring of ultrasound efficiency (20KHZ) in the inactivation of Salmonella Typhimurium, and Escherichia coli in inoculated pork samples treated for 10, 20 and 30 min. Weibull, and Log-linear model fitted well (R2 ≥ 0.9) for both Salmonella Typhimurium, and Escherichia coli inactivation kinetics. The study also revealed that ultrasound has antimicrobial effects on the pathogens. For qualitative analysis, unsupervised (PCA) and supervised (LDA) chemometric algorithms were applied. PCA was used for successful sample clustering and LDA approach was used to construct statistical models for the classification of ultrasound treated and untreated samples. LDA showed classification accuracies of 99.26%,99.63%,99.70%, 99.43% for E-nose - S. Typhimurium, E-nose -E. coli, HSI - S. Typhimurium and HSI -E. coli respectively. PLSR quantitative models showed robust models for S. Typhimurium- (E-nose Rp2 = 0.9375, RMSEP = 0.2107 log CFU/g and RPD = 9.7240 and (HSI Rp2 = 0.9687 RMSEP = 0.1985 log CFU/g and RPD = 10.3217) and E. coli -(E-nose -Rp2 = 0.9531, RMSEP = 0.2057 log CFU/g and RPD = 9.9604) and (HIS- Rp2 = 0.9687, RMSEP = 0.2014 log CFU/g and RPD = 10.1731). This novel study shows the overall effectiveness of applying E-nose and HSI for in-situ and nondestructive detection, discrimination and quantification of bacterial foodborne pathogens during the application of food processing technologies like ultrasound for pathogen inactivation.

Inactivation of Salmonella Enteritidis on cherry tomatoes by ultrasound, lactic acid, detergent, and silver nanoparticles

Ultrasound (US) combined with chemical agents could represent an effective method for decontaminating fruits and vegetables. This study aimed to evaluate the use of US (40 kHz for 5 min) alone or with 1% lactic acid (LA), 1% commercial detergent (DET), or 6 mg/L silver nanoparticles (AgNP, average diameter 100 nm) as an alternative treatment to 200 mg/L sodium dichloroisocyanurate for inactivating Salmonella enterica serovar Enteritidis present on cherry tomatoes. The interfacial tension between sanitizing solutions and bacterial adhesion was investigated. Sanitizers in solutions with DET and AgNP had lower surface tension. All treatments, except that with DET, reduced Salmonella Enteritidis by more than one logarithmic cycle. There was no significant difference between the mean values of log colony-forming units (CFU)/g reduction in all treatments. Transmission electron microscopy revealed the loss of the Salmonella Enteritidis capsule following treatment with US and with US + LA. Salmonella Enteritidis counts (2.29 log CFU/g) in cherry tomatoes were markedly reduced to safe levels by treatment with the combination of AgNP and US + LA (2.37 log CFU/g).