Study of the Antibacterial Potency of Electroactivated Solutions of Calcium Lactate and Calcium Ascorbate on Bacillus cereus ATCC 14579 Vegetative Cells.

Bacillus cereus is a pathogenic bacterium, Gram-positive, aerobic, and facultative anaerobic that can produce spores and different toxins. It is involved in serious foodborne illnesses such as the diarrheal and emetic syndromes, depending on the ingested toxin. This work is aimed to study the potency of electroactivated solutions (EAS) of calcium lactate, calcium ascorbate, and their mixture as antibacterial agents against B. cereus ATCC 14579 vegetative cells. The solutions used were electroactivated under electric current intensities of 250, 500, and 750 mA for 30 min. The obtained EAS were tested in direct contact with B. cereus (107 CFU/mL) for different durations ranging from 5 s to 2 min. Moreover, standard lactic and ascorbic acids were tested as controls at equivalent titratable acidity as that of the corresponding electroactivated solutions. The obtained results showed that EAS exhibit high antibacterial efficacy against B. cereus vegetative cells. The EAS obtained after electroactivation of calcium lactate and calcium ascorbate were more efficient than those of their corresponding standard acids (lactic and ascorbic). The observed antibacterial effect of the EAS resulted in a reduction of 7 log CFU/mL after 5 s of direct contact in some specific cases. Scanning (SEM) and transmission (TEM) electron microscopic observations provided conclusive evidence of the antibacterial activity of the used EAS. These results outlined the highly antimicrobial potency of EAS against B. cereus vegetative cells and that they can be considered in an eventual strategy to ensure food safety, surface cleaning, as well as replacement of hazardous disinfecting chemicals.

Correction to "Development of a Process for Color Improvement of Low Grade Dark Maple Syrup by Adsorption on Activated Carbon".

[This corrects the article DOI: 10.1021/acsomega.0c02717.].

Study of the impacts of electro-activated solutions of calcium lactate, calcium ascorbate and their equimolar mixture combined with moderate heat treatments on the spores of Bacillus cereus ATCC 14579 under model conditions and in fresh salmon.

Widespread in very diverse environments, the spores of Bacillus cereus are highly resistant to hostile conditions and can contaminate a huge variety of food products, posing a potential health hazard to consumers. Given this significant risk, the objective of this research work was to study the impacts of electro-activated solutions (EAS) made with calcium ascorbate, calcium lactate, and their equimolar mixture on Bacillus cereus ATCC 14579 spores in model conditions and food matrix, the fresh Atlantic salmon. The model conditions consisted of a direct application of the EAS to the spores, which avoided any interference with factors external to those of the solutions. Salmon was chosen as a food model because it is a product sensitive to bacterial spoilage and can be eaten raw. To achieve this, the solutions were prepared by electro-activation using an electric current with an intensity of 750 mA for 30 min, resulting in mean pH values of 1.94 ± 0.15-2.16 ± 0.01 and titratable acidity of 0.102 ± 0.001-0.109 ± 0.001 mol/L, depending on the type of solution. These conditions were chosen because of their excellent antibacterial efficacy previously demonstrated against vegetative cells of B. cereus. The results showed high sporicidal activities of the EAS against B. cereus with a 7 to 9 log reduction, using an initial spore population of 109 CFU/mL, depending on the conditions evaluated, namely: in direct contact (2-30 min), in salmon used as a food matrix (2-7 min), and in combination with moderate heat treatments from 60 to 90 °C (0.5-2 min). In addition, it was observed that the sporicidal capacity of the EAS increased with temperature and the contact time. Otherwise, analysis of the color and lipids of the salmon have not shown any major impacts of the use of EAS as a rinsing solution for this highly perishable food. Furthermore, micrographs taken by scanning and transmission electron microscopy revealed the destructive effects of the EAS used in the vital structures/components of the spores. In general, this study has demonstrated that the electro-activation technology is effective in producing EAS capable of destroying/inactivating B. cereus spores and that they can be used for the improvement of food safety and preservation.

Study of the Electro-Activation Process of Calcium Lactate, Calcium Ascorbate Solutions, and Their Equimolar Mixture: Assessment of Their Physicochemical Properties.

The aim of this study was to prepare electro-activated solutions (EAS) from calcium lactate, calcium ascorbate, and an equimolar mixture of these two salts to obtain their corresponding acids and to study their physicochemical characteristics, in particular, pH, titratable acidity, pK a, and antioxidant activity. Indeed, the solutions were electro-activated in a reactor comprising three compartments (anodic, central, and cathodic) separated by anionic and cationic exchange membranes, respectively. The electric current intensities used were set at 250, 500, and 750 mA for a maximum period of 30 min. In general, the EAS obtained at 750 mA for 30 min showed the lowest pH (2.16, 2.08, 1.94) and pK a (3.13, 3.07, 2.90) values and the highest titratable acidity (0.107, 0.102, 0.109 mol/L) for calcium lactate, the mixture, and calcium ascorbate, respectively. In addition, the obtained results have demonstrated that the pH, titratable acidity, and pK a of the EAS varied proportionally and significantly (p < 0.001) with the duration of the experiment and the intensity of the electric current applied. To evaluate the migration of calcium (Ca2+) between the central and the cathodic compartments of the reactor, the concentration of Ca2+ was determined especially in the cathodic section by inductively coupled plasma optical emission spectroscopy (ICP-OES). The results showed that the migration of Ca2+ varied proportionally with the electric current intensity. In this context, analysis by Fourier transform infrared (FTIR) spectroscopy, high-performance liquid chromatography (HPLC), and differential scanning calorimetry (DSC) have confirmed the production of lactic acid and ascorbic acid compared to standards. In addition, analysis by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging technique confirmed high antioxidant activities of >90 and >83% for calcium ascorbate and the mixture, respectively, in comparison to the standard ascorbic acid (85%). Overall, this research has clearly demonstrated the eventual potential of electro-activation to produce highly reactive organic acids from their conjugated salts. These EAS can become excellent antimicrobial and sporicidal agents in the food processing industry.

Development of a Process for Color Improvement of Low-Grade Dark Maple Syrup by Adsorption on Activated Carbon.

Low-grade dark maple syrup was successfully discolored on activated carbon. Several experimental parameters were tested, namely, the mixing time (20, 40, and 60 min), concentration of the activated carbon (0.1, 0.3, and 0.5 g/100 mL), type of activated carbon (I, II, and III), activated carbon particle size (25, 50, and 75 µm), stirring speed (200, 400, and 600 rpm), and temperature (40, 60, and 80 °C). The obtained results showed that the discoloration is optimal by applying the following parameters: a mixing time of 40 min with a type III activated carbon at a concentration of 0.3 g/100 mL. These parameters yielded a light transmittance at 560 nm of 83.70 ± 0.21%, which ranks the syrup in the extra clear class according to the Canadian classification. The results showed that among the tested carbons, the adsorption on the type III carbon followed the Langmuir, Freundlich, and Langmuir-Freundlich adsorption isotherms. Regarding the effect of the particle size, the obtained results showed that a mean size of 25 µm combined with a stirring speed of 200 rpm and working temperature of 80 °C was the most effective one. The optimized conditions showed a good adequacy with the Langmuir and Freundlich models. The discoloration process by using the type III activated carbon followed the pseudo-second-order kinetics.

Kluyveromyces marxianus: An emerging yeast cell factory for applications in food and biotechnology.

Several yeasts, which are eukaryotic microorganisms, have long been used in different industries due to their potential applications, both for fermentation and for the production of specific metabolites. Kluyveromyces marxianus is one of the most auspicious nonconventional yeasts, generally isolated from wide-ranging natural habitats such as fermented traditional dairy products, kefir grain, sewage from sugar industries, sisal leaves, and plants. This is a food-grade yeast with various beneficial traits, such as rapid growth rate and thermotolerance that make it appealing for different industrial food and biotechnological applications. K. marxianus is a respiro-fermentative yeast likely to produce energy by either respiration or fermentation pathways. It generates a wide-ranging specific metabolites and could contribute to a variety of different food and biotechnological industries. Although Saccharomyces cerevisiae is the most widely used dominant representative in all aspects, many applications of K. marxianus in biotechnology, food and environment have only started to emerge nowadays; some of the most promising applications are reviewed here. The general physiology of K. marxianus is outlined, and then the different applications are discussed: first, the applications of K. marxianus in biotechnology, and then the recent advances and possible applications in food, feed and environmental industries. Finally, this review provides a discussion of the main challenges and some perspectives for targeted applications of K. marxianus in the modern food technology and applied biotechnology in order to exploit the full potential of this yeast which can be used as a cell factory with great efficiency.

A comparative study of the functional properties and antioxidant activity of soybean meal extracts obtained by conventional extraction and electro-activated solutions.

Functional properties and antioxidant activity of soybean meal extracts obtained by conventional chemical method were compared to those obtained by using electro-activated solutions. The conventional extract obtained at pH8 had the highest WAC (400 ±â€¯7 g/100 g), while the lowest was that of samples extracted under pH3. Extract obtained using electro-activated solution Anolyte_300mA-30 min had WAC value (25 ±â€¯1 g/100 g). OAC was the highest for samples extracted under alkaline conditions whatever the extraction mode used with values of 5.50 ±â€¯0.54 to 6.85 ±â€¯0.62 mL/g. FC of the conventional extracts was higher compared to those extracted by electro-activation with maximal value of 52% for the conventional sample obtained at pH9, whereas the maximal FC of 28% was observed for the electro-activated sample obtained by using Anolyte_450mA-50 min. Electro-activated showed higher EP. Conventional extracts showed higher antioxidant activity (92.31 ±â€¯1.5%) than those obtained by electro-activation (47.46 ±â€¯0.94%).