Quality attributes optimization of orange juice subjected to multi-frequency thermosonication: Alicyclobacillus acidoterrestris spore inactivation and applied spectroscopy ROS characterization

Synergistic Effect of Thermosonication on the Stability of Bioactive Compounds and Antioxidant Activity of Blackberry Juice

Thermosonication is a technique that combines ultrasound with mild temperatures and can be applied as an alternative to thermal pasteurization. This study aimed to evaluate the synergistic effect of thermosonication (Termo) on bioactive compounds (total anthocyanins concentration and total phenolic compounds), antioxidant activity and physicochemical characteristics of blackberry juice in comparison with conventional heat treatment (TT). The experiment was conducted based on the Central Composite Rotational Design, varying the amplitude (60% and 90%), temperature (64 °C and 86 °C) and time (114 s and 517 s) factors. The results showed that the amplitude and temperature factors significantly influenced (p < 0.05) the content of bioactive compounds studied, as well as the antioxidant activity and physicochemical properties, showing that the thermosonication treatment using 60% ultrasonic amplitude and 86 °C temperature provided more excellent retention and less degradation in the content of anthocyanins, phenolic compounds, antioxidant activity, and physicochemical properties (pH, acidity, total soluble solids and colour) of blackberry juice. Higher ultrasonic amplitude (90%) promoted changes in the physicochemical properties and degradation of the bioactive compounds studied and antioxidant activity. However, the limitations of this study are related to the specific matrix used, the seasonality of these fruits, the availability of raw material for processing and the limitation of large-scale ultrasonic equipment. These factors limit the expansion of these findings to other products. Overall, thermosonication can be considered a promising technique. Still, for its implementation as a possible alternative to conventional thermal methods, further studies are needed to investigate the stability of bioactive compounds and antioxidant activity of blackberry juice better.

Investigating the triple-frequency ultrasound-assisted fermented rice lees: Impact on physicochemical, structural, morphological, and metabolic properties

This study examined the effect of triple-frequency ultrasound treatment (TFUT)-assisted lactic acid bacteria (LAB-L. plantarum and L. helveticus fermentation for 24-h and 48-h) on the chemical, structural, morphological, metabolic, and sensory properties of rice lees (RL). Ultrasonicated-assisted RL fermented with L. helveticus (URLH-48) had the greatest total phenolic contents (TPC) (112.1 mg GAE/m), total flavonoid contents (TFC) (163.62 mg RE/mL), and proanthocyanidin contents (PAC) (728.34 mg/mL) compared to RL (control) and other treatments. Furthermore, URLH-48 demonstrated an increase in the concentrations of quinic acid (486.96 mg/L) and gallic acid (201.42 mg/L), as determined by HPLC-UV analysis. Additionally, FTIR spectral analyses demonstrated that TFUT-assisted fermented RL exhibited a greater degree of flexibility and mobility in its secondary structures compared to RL (control). The amino acid's profile of RL was significantly increased as LAB degraded the RL proteins, and the function of TFUT facilitates bacterial activity. Moreover, SEM observation provides convincing evidence that TFUT improves and speeds up the breakdown of proteins' structures, resulting in irregular and dense structures. Correlation and molecular docking research suggest that TFUT has different impacts on specific RL and fermented RL characteristics. The analyses conducted using GC-MS and E-nose indicated the generation of highly volatile flavor compounds through fermentation. The sensory evaluation results show an increase in liking following fermentation and TFUT-assisted fermentation, which is attributed to the production of flavor compounds. Consequently, the combined use of TFUT-assisted fermentation markedly improves the polyphenolic composition, antioxidant capacity, flavor profile, micromorphology, and overall quality of RL, which may enhance their functionality and broaden their applications in the food industry.

Inactivation of Pichia membranaefaciens in Soybean Paste by Dual-Frequency and Moderate Thermosonication

Dual-frequency and moderate thermosonication (TS, 300 + 300 W, 20 + 40 kHz, 25~60 °C) was employed to inactivate Pichia membranifaciens in soybean paste. The aim was to evaluate the effect of TS on the inactivation of P. membranaefaciens and on the quality of soybean paste. The Weibull model fitted the survival data of P. membranaefaciens in thermosonicated soybean paste well and a decrease of 5 log of P. membranaefaciens in soybean paste was obtained at TS50°C, TS55°C, TS60°C, and T65°C for 15.41, 7.49, 2.27, and 18.61 min. Scanning electron microscope observation revealed TS50°C damaged the cell structure, leading to the leakage of intracellular contents. The physicochemical properties of soybean paste treated by TS were more retained than in paste treated by heat. The GC-MS analysis indicated that the flavor components had increased after TS treatment, especially at TS50°C. In conclusion, TS can inactive P. membranaefaciens in soybean paste without causing significant changes in its physicochemical and flavor qualities.

Pyrococcus furiosus argonaute based Alicyclobacillus acidoterrestrsis detection in fruit juice

Alicyclobacillus acidoterrestris is the major threat to fruit juice for its off-odor producing characteristic. In this study, Pyrococcus furiosus Argonaute (PfAgo), a novel endonuclease with precise DNA cleavage activity, was used for A. acidoterrestrisdetection, termed as PAD. The partially amplified 16 S rRNA gene of A. acidoterrestris can be cleaved by PfAgo activated by a short 5'-phosphorylated single strand DNA, producing a new guide DNA (gDNA). Then, PfAgo was activated by the new gDNA to cut a molecular beacon (MB) with fluorophore-quencher reporter, resulting in the recovery of fluorescence. The fluorescent intensity is positively related with the concentration of A. acidoterrestris. The PAD assay showed excellent specificity and sensitivity as low as 101 CFU/mL, which can be a powerful tool for on-site detection of A. acidoterrestris in fruit juice industry in the future, reducing the economic loss.

Enzyme-Assisted Endogenous Guide DNA Generation-Mediated Pyrococcus furiosus Argonaute for Alicyclobacillus acidoterrestris Detection

Pyrococcus furiosusArgonaute (PfAgo) emerged as a novel endonuclease for the nucleic acid test recently. However, the input of exogenous guide DNA (gDNA) to activate PfAgo has reduced its flexibility. In this work, an enzyme-assisted endogenous gDNA generation-mediated PfAgo for the target detection strategy, termed EGG-PAD, was proposed. With the aid of EcoR Ι, the target double-strand DNA was cut, producing a phosphate group at the 5' end, functioning as gDNA to activate PfAgo for nucleic acid detection. The applicability of this assay was tested in the detection ofAlicyclobacillus acidoterrestris, a bacterium causing the spoilage of fruit juice, showing excellent sensitivity and specificity, ascribed to the "duplex amplification and triple insurance" mechanism. Moreover, EGG-PAD exhibited superior versatility in the identification of common foodborne pathogens. This powerful platform could also be an on-site test tool for detecting nucleic acid-containing organisms such as tumor cell, pathogen, and virus in the future.

Effect of dual-frequency thermosonication, food matrix, and germinants on Alicyclobacillus acidoterrestris spore germination

The off-odors associated with spoilage of acidic beverages are linked to the germination and growth of Alicyclobacillus acidoterrestris (AAT) spores. As a consequence, we determined the influence of nutrients, non-nutrient germinants, dual-frequency thermosonication (DFTS), and food matrix on spore germination. AAT spores in orange juice (OJ), supplemented by L-alanine (L-ala), had the highest germination rate and lowest DPA content at 10 h of incubation. The formation of microscopic pores in cell membranes during DFTS caused irreversible damage in AAT spores in citrate buffer solution (CBS); however, it stimulated AAT spore germination in CBS containing L-ala. Hence, the germination potential was established in the order: L-ala > Calcium dipicolinate > asparagine, glucose, fructose, and potassium ion mixture (AGFK) > L-valine. The conductivity analysis indicated that membrane damage could be a key factor contributing to the artificial germination in CBS. AFM images revealed that after 2 h of adding L-ala, the protein content increased with increased germinated cells. TEM showed that membrane poration and coat detachment were the main pre-germination morphological changes detected after DFTS treatment. This study provides evidence that germination stimulated with DFTS might be an effective strategy for reducing A. acidoterrestris spores in fruit juices.

Non-thermal emerging processing Technologies: Mitigation of microorganisms and mycotoxins, sensory and nutritional properties maintenance in clean label fruit juices

The increase in the fruit juice consumption and the interest in clean label products boosted the development and evaluation of new processing technologies. The impact of some emerging non-thermal technologies in food safety and sensory properties has been evaluated. The main technologies applied in the studies are ultrasound, high pressure, supercritical carbon dioxide, ultraviolet, pulsed electric field, cold plasma, ozone and pulsed light. Since there is no single technique that presents high potential for all the evaluated requirements (food safety, sensory, nutritional and the feasibility of implementation in the industry), the search for new technologies to overcome the limitations is fundamental. The high pressure seems to be the most promising technology regarding all the aspects mentioned. Some of the outstanding results are 5 log reduction of E. coli, Listeria and Salmonella, 98.2% of polyphenol oxidase inactivation and 96% PME reduction. However its cost can be a limitation for industrial implementation. The combination of pulsed light and ultrasound could overcome this limitation and provide higher quality fruit juices. The combination was able to achieve 5.8-6.4 log cycles reduction of S. Cerevisiae, and pulsed light is able to obtain PME inactivation around 90%, 61.0 % more antioxidants, 38.8% more phenolics and 68.2% more vitamin C comparing to conventional processing, and similar sensory scores after 45 days at 4 °C comparing to fresh fruit juice. This review aims to update the information related to the application of non-thermal technologies in the fruit juice processing through systematic and updated data to assist in industrial implementation strategies.

Application and potential of multifrequency ultrasound in juice industry: Comprehensive analysis of inactivation and germination of Alicyclobacillus acidoterrestris spores

The majority of acidic fruits are perishable owing to their high-water activity, which promotes microbial activity, thus exhibiting metabolic functions that cause spoilage. Along with sanitary practices, several treatments are used during processing and/or storage to inhibit the development of undesirable bacteria. To overcome the challenges caused by mild heat treatment, juice manufacturers have recently increased their involvement in developing novel non-thermal processing procedures. Ultrasonication alone or in combination with other hurdle technologies may be used to pasteurize processed fruit juices. Multifrequency ultrasound has gained popularity due to the fact that mono-frequency ultrasound has less impact on bacterial inactivation and bioactive compound enhancement of fruit juice. Here, we present and discuss the fundamental information and technological knowledge of how spoilage bacteria, specifically Alicyclobacillus acidoterrestris, assemble resistant spores and inactivate and germinate dormant spores in response to nutrient germinants and physical treatments such as heat and ultrasound. To the authors' knowledge, no prior review of ultrasonic inactivation and germination of A. acidoterrestris in fruit juice exists. Therefore, this article aims to provide a review of previously published research on the inactivation and germination of A. acidoterrestris in fruit juice by ultrasound and heat.

Toward in-process technology-aided automation for enhanced microbial food safety and quality assurance in milk and beverages processing

Ensuring the safety of food products is critical to food production and processing. In food processing and production, several standard guidelines are implemented to achieve acceptable food quality and safety. This notwithstanding, due to human limitations, processed foods are often contaminated either with microorganisms, microbial byproducts, or chemical agents, resulting in the compromise of product quality with far-reaching consequences including foodborne diseases, food intoxication, and food recall. Transitioning from manual food processing to automation-aided food processing (smart food processing) which is guided by artificial intelligence will guarantee the safety and quality of food. However, this will require huge investments in terms of resources, technologies, and expertise. This study reviews the potential of artificial intelligence in food processing. In addition, it presents the technologies and methods with potential applications in implementing automated technology-aided processing. A conceptual design for an automated food processing line comprised of various operational layers and processes targeted at enhancing the microbial safety and quality assurance of liquid foods such as milk and beverages is elaborated.

Non-conventional Stabilization for Fruit and Vegetable Juices: Overview, Technological Constraints, and Energy Cost Comparison

This study will provide an overview and a description of the most promising alternatives to conventional thermal treatments for juice stabilization, as well as a review of the literature data on fruit and vegetable juice processing in terms of three key parameters in juice production, which are microbial reduction, enzyme inactivation, and nutrient-compound retention. The alternatives taken into consideration in this work can be divided, according to the action mechanism upon which these are based, in non-conventional thermal treatments, among which microwave heating (MWH) and ohmic heating (OH), and non-thermal treatments, among which electrical treatments, i.e., pulsed electric fields (PEF), high-pressure processing (HPP), radiation treatments such as ultraviolet light (UVL) and high-intensity pulsed light (PL), and sonication (HIUS) treatment, and inert-gas treatments, i.e., the pressure change technology (PCT) and supercritical carbon dioxide (SC-CO2) treatments. For each technology, a list of the main critical process parameters (CPP), advantages (PROS), and disadvantages (CONS) will be provided. In addition, for the non-thermal technologies, a summary of the most relevant published result of their application on fruit and vegetable juices will be presented. On top of that, a comparison of typical specific working energy costs for the main effective and considered technologies will be reported in terms of KJ per kilograms of processed product.

Application of multi-frequency power ultrasound in selected food processing using large-scale reactors: A review

Ultrasound as an eco-friendly green technology has been widely studied in food processing. Nevertheless, there is a lack of publications regarding the application of ultrasound in food processing using large-scale reactors. In this paper, the mechanisms and the devices of multi-frequency power ultrasound (MFPU) are described. Moreover, the MFPU applied in enzymolysis of protein, and washing of fruits and vegetables are reviewed. The application of MFPU can improve the enzymolysis of protein through modification on enzyme, modification on substrate materials, and facilitation of the enzymatic hydrolysis process. The ultrasound treatment can enhance the removal of microorganisms, and pesticides on the surface of fruits and vegetables. Furthermore, the reactors of ultrasound-assisted enzymolysis of protein, and washing of fruits and vegetables on the industrial scale are also detailed. This review paper also considers future trends, limitations, drawbacks, and developments of ultrasound application in enzymolysis and washing.