Efficacy of chlorine dioxide gas and freezing rate on the microbiological quality of frozen blueberries

A Review: Gaseous Interventions for Listeria monocytogenes Control in Fresh Apple Cold Storage

Listeria monocytogenes (L. monocytogenes) causes an estimated 1600 foodborne illnesses and 260 deaths annually in the U.S. These outbreaks are a major concern for the apple industry since fresh produce cannot be treated with thermal technologies for pathogen control before human consumption. Recent caramel apple outbreaks indicate that the current non-thermal sanitizing protocol may not be sufficient for pathogen decontamination. Federal regulations provide guidance to apple processors on sanitizer residue limits, organic production, and good manufacturing practices (GMPs). However, optimal methods to control L. monocytogenes on fresh apples still need to be determined. This review discusses L. monocytogenes outbreaks associated with caramel apples and the pathogen’s persistence in the environment. In addition, this review identifies and analyzes possible sources of contaminant for apples during cold storage and packing. Gaseous interventions are evaluated for their feasibility for L. monocytogenes decontamination on apples. For example, apple cold storage, which requires waterless interventions, may benefit from gaseous antimicrobials like chlorine dioxide (ClO₂) and ozone (O₃). In order to reduce the contamination risk during cold storage, significant research is still needed to develop effective methods to reduce microbial loads on fresh apples. This requires commercial-scale validation of gaseous interventions and intervention integration to the current existing apple cold storage. Additionally, the impact of the interventions on final apple quality should be taken into consideration. Therefore, this review intends to provide the apple industry suggestions to minimize the contamination risk of L. monocytogenes during cold storage and hence prevent outbreaks and reduce economic losses.

Food safety knowledge, attitude, and hygiene practices of street-cooked food handlers in North Dayi District, Ghana

BACKGROUND

Food safety and hygiene are currently a global health apprehension especially in unindustrialized countries as a result of increasing food-borne diseases (FBDs) and accompanying deaths. This study aimed at assessing knowledge, attitude, and hygiene practices (KAP) of food safety among street-cooked food handlers (SCFHs) in North Dayi District, Ghana.

METHODS

This was a descriptive cross-sectional study conducted on 407 SCFHs in North Dayi District, Ghana. The World Health Organization's Five Keys to Safer Food for food handlers and a pretested structured questionnaire were adapted for data collection among stationary SCFHs along principal streets. Significant parameters such as educational status, average monthly income, registered SCFHs, and food safety training course were used in bivariate and multivariate logistic regression models to calculate the power of the relationships observed.

RESULTS

The majority 84.3% of SCFHs were female and 56.0% had not attended a food safety training course. This study showed that 67.3%, 58.2%, and 62.9% of SCFHs had good levels of KAP of food safety, respectively. About 87.2% showed a good attitude of separating uncooked and prepared meal before storage. Good knowledge of food safety was 2 times higher among registered SCFHs compared to unregistered [cOR=1.64, p=0.032]. SCFHs with secondary education were 4 times good at hygiene practices of food safety likened to no education [aOR=4.06, p=0.003]. Above GHc1500 average monthly income earners were 5 times good at hygiene practices of food safety compared to below GHc500 [aOR=4.89, p=0.006]. Registered SCFHs were 8 times good at hygiene practice of food safety compared to unregistered [aOR=7.50, p<0.001]. The odd for good hygiene practice of food safety was 6 times found among SCFHs who had training on food safety courses likened to those who had not [aOR=5.97, p<0.001].

CONCLUSIONS

Over half of the SCFHs had good levels of KAP of food safety. Registering as SCFH was significantly associated with good knowledge and hygiene practices of food safety. Therefore, our results may present an imperative foundation for design to increase food safety and hygiene practice in the district, region, and beyond.

Shelf-life, quality, safety evaluations of blueberry fruits coated with chitosan nano-material films

Chitosan coating (B/CH) in addition with nano-material films as silicon (B/CH/Nano-SiO₂) and titanium (B/CH/Nano-TiO₂) dioxides were developed and applied to detect potential changes on fresh blueberry fruits in commercial storage temperature. Physical, mechanical parameters (weight loss, decay rate, colour index and firmness), phytochemical contents (ascorbic acid, acidity, soluble solids concentration, titratable acidity, and repining index), phenolic enzymes (peroxidase and polyphenoloxidase), pigments (anthocyanin) and microbiological analysis (mesophilic aerobic, yeasts and molds populations) were detected every other day until the end of the experiment. Nano-coating based on (Nano-TiO₂) established the most suitable values for weight loss (2.22%), titratable acidity (0.45% citric acid), and repining index. (B/CH/Nano-TiO₂) reported a gradual increase in polyphenoloxidase and peroxidase enzyme activities (659.45 U/min g) and (20.39 U/min g), respectively. While, (B/CH/Nano-SiO₂) established the slightest change in acidity (2.61), anthocyanin (105.19 cyanidin-3-O-glucoside mg/100 g FW) and minimized the growth of mesophilic aerobic, yeasts, and molds populations (3.73–3.98 log CFU/g), respectively. (B/CH) films maintained lightness (6.80% loss) and recorded the highest ascorbic acid content (7.34 g/100 g FW). Therefore, chitosan nano-material films can maintain nutrients and control the microbial growth for extending the shelf life of fresh blueberry fruits.

Strategies for Microbial Decontamination of Fresh Blueberries and Derived Products

Increasing consumption of blueberries is associated with appreciation of their organoleptic properties together with their multiple health benefits. The increasing number of outbreaks caused by pathogenic microorganisms associated with their consumption in the fresh state and the rapid spoilage of this product which is mainly caused by moulds, has led to the development and evaluation of alternatives that help mitigate this problem. This article presents different strategies ranging from chemical, physical and biological technologies to combined methods applied for microbial decontamination of fresh blueberries and derived products. Sanitizers such as peracetic acid (PAA), ozone (O3), and electrolyzed water (EOW), and physical technologies such as pulsed light (PL) and cold plasma (CP) are potential alternatives to the use of traditional chlorine. Likewise, high hydrostatic pressure (HHP) or pulsed electrical fields (PEF) successfully achieve microbial reductions in derivative products. A combination of methods at moderate intensities or levels is a promising strategy to increase microbial decontamination with a minimal impact on product quality.

Identification of spoilage microorganisms in blueberry juice and their inactivation by a microchip pulsed electric field system

Blueberry juice is a healthy and nutritious food that has become increasingly popular worldwide. However, little is known about the microbial groups of this juice that can cause its spoilage. This study aimed to identify the main spoilage microorganisms in blueberry juice and explore whether a microchip pulsed electric field (MPEF) can effectively inactivate them. We performed polymerase chain reaction (PCR) amplification, as well as 16S rDNA, 18S rDNA, internal transcribed spacer (ITS), and 26S rDNA gene sequence analyses. Nine species belonging to eight genera, including Pantoea, Burkholderia, Pichia, Meyerozyma, Cryptococcus, Aureobasidium, Cladosporium, and Penicillium were identified as spoilage microorganisms. Cryptococcus sp., Meyerozyma sp., and Pichia sp. were specific spoilage organisms (SSO) owing to their rising numbers throughout spoilage progression. The effect of MPEF on the potential inactivation of these microorganisms was to induce significant inactivation of viable Cryptococcus sp., Meyerozyma sp., and Pichia sp. This research provides a theoretical basis for the application of MPEF in improving the quality of blueberry juice.