The impact of biopreservatives and storage temperature in the quality and safety of minimally processed mixed vegetables for soup

Advances in propolis and propolis functionalized coatings and films for fruits and vegetables preservation

Propolis, as a natural active substance, is rich in polyphenols, with low toxicity, antioxidant, antifungal and antibacterial properties, which can be applied to the post-harvest preservation of fruits and vegetables. Propolis extracts and propolis functionalized coatings and films have exhibited good freshness in various types of fruits and vegetables as well as fresh-cut vegetables. They are mainly used to prevent water loss after harvesting, to inhibit the infestation of bacteria and fungi after harvesting and to enhance the firmness and apparent quality of fruits and vegetables. Moreover, propolis and propolis functionalized composites have a small or even insignificant effect on the physicochemical parameters of fruits and vegetables. Furthermore, how to cover the special smell of propolis itself so that it does not affect the flavor of fruits and vegetables, and the application of propolis extract in wrapping paper and packaging bag of fruits and vegetables, are worthwhile to further investigate.

Effect of Processing Treatment and Modified Atmosphere Packing on Carrot's Microbial Community Structure by Illumina MiSeq Sequencing

The aim of this study was to analyze the microbiome of carrot (Daucus carota subsp. sativus) subjected to minimal pre-treatment (rinsing in organic acid solution) and packaging in a high-oxygen modified atmosphere, and then stored for 17 days under refrigeration conditions (4 °C). The highest levels of bacteria in the carrot microbiome were characterized, at almost 78%, by bacteria belonging to the Enterobacteriaceae and Pseudomonadaceae families. Rinsing in a solution of ascorbic and citric acids resulted in the improvement of microbiological quality in the first day of storage. However, the use of a high-oxygen modified atmosphere extended the shelf life of the minimally processed product. Compared to carrots stored in air, those stored in high oxygen concentration were characterized by a greater ratio of bacteria belonging to the Serratia and Enterobacter genera, and a lower ratio belonging to the Pseudomonas and Pantoea genera. Moreover, the β-biodiversity analysis confirmed that the oxygen concentration was the main factor influencing the differentiation of the metabiomes of the stored carrots. The bacterial strains isolated from carrots identified by molecular methods were mostly pathogenic or potentially pathogenic microorganisms. Neither the minimal pre-treatment nor packaging in high-oxygen atmosphere was able to eliminate the threat of pathogenic bacteria emerging in the product.

Applications of Essential Oils as Antibacterial Agents in Minimally Processed Fruits and Vegetables—A Review

Microbial foodborne diseases are a major health concern. In this regard, one of the major risk factors is related to consumer preferences for “ready-to-eat” or minimally processed (MP) fruits and vegetables. Essential oil (EO) is a viable alternative used to reduce pathogenic bacteria and increase the shelf-life of MP foods, due to the health risks associated with food chlorine. Indeed, there has been increased interest in using EO in fresh produce. However, more information about EO applications in MP foods is necessary. For instance, although in vitro tests have defined EO as a valuable antimicrobial agent, its practical use in MP foods can be hampered by unrealistic concentrations, as most studies focus on growth reductions instead of bactericidal activity, which, in the case of MP foods, is of utmost importance. The present review focuses on the effects of EO in MP food pathogens, including the more realistic applications. Overall, due to this type of information, EO could be better regarded as an “added value” to the food industry.

Effect of natural antimicrobial agent (MicroGARD) combined with edible coating (NatureSeal) treatment on fresh-cut butternut squash

To improve fresh-cut produce quality and shelf life, 0.5% or 1.0% MicroGARD^® 730 (MG) as a natural alternative to synthetic chemical preservatives, 2.5% NatureSeal^® (NS) product (vitamin/mineral-based blends), 0.5% MG combined with 2.5% NS, and 1% MG combined with 2.5% NS were used to treat fresh-cut butternut squash (Cucurbita moschata). The 240 g samples were put into food grade bags and stored at 4 or 7 °C. Microbial population, including aerobic plate counts (APCs), yeast and molds, total coliforms, and quality parameters, including head space O₂ /CO₂ concentration in package, pH, soluble solids, color, and conductivity, were evaluated after 0, 3, 6, 9, 12, and 20 days of storage. Results showed that after 6 days of storage at 7 °C, APC of check and control samples reached to 2.6 × 10⁸ and 1.5 × 10⁷ CFU/g, respectively; while they were kept at 10⁴ CFU/g (3 to 4 log reduction) in the squash samples treated with 0.5% or 1% MG combined with NS at 7 °C. Similar results were found on squash samples stored at 4 °C for 9 days. The cut squash treated with MG combined with NS had APC ≤ 10⁷ CFU/g at 4 °C for about 20 days compared to 9 days in controls or 0.5% MG-treated samples, and 12 days in 1% MG-treated or NS-treated samples, respectively. Considering overall quality and extended shelf life, MG combined with NS was recommended to apply to cut squashes stored at 4 °C. PRACTICAL APPLICATION: This research provided useful information and practical treatment application for developing fresh-cut produce with good quality and extended shelf life up to 20 days at 4 °C.

Role of biological control agents and physical treatments in maintaining the quality of fresh and minimally-processed fruit and vegetables

Fruit and vegetables are an important part of human diets and provide multiple health benefits. However, due to the short shelf-life of fresh and minimally-processed fruit and vegetables, significant losses occur throughout the food distribution chain. Shelf-life extension requires preserving both the quality and safety of food products. The quality of fruit and vegetables, either fresh or fresh-cut, depends on many factors and can be determined by analytical or sensory evaluation methods. Among the various technologies used to maintain the quality and increase shelf-life of fresh and minimally-processed fruit and vegetables, biological control is a promising approach. Biological control refers to postharvest control of pathogens using microbial cultures. With respect to application of biological control for increasing the shelf-life of food, the term biopreservation is favored, although the approach is identical. The methods for screening and development of biocontrol agents differ greatly according to their intended application, but the efficacy of all current approaches following scale-up to commercial conditions is recognized as insufficient. The combination of biological and physical methods to maintain quality has the potential to overcome the limitations of current approaches. This review compares biocontrol and biopreservation approaches, alone and in combination with physical methods. The recent increase in the use of meta-omics approaches and other innovative technologies, has led to the emergence of new strategies to increase the shelf-life of fruit and vegetables, which are also discussed herein.

Influence of polysaccharide-based edible coatings as carriers of prebiotic fibers on quality attributes of ready-to-eat fresh blueberries

BACKGROUND

Little information is available regarding the effect of dietary fibers added into edible coatings on quality attributes of ready-to-eat fruits. The aim of this study was to evaluate the effects of sodium alginate (AL) and chitosan (CH) edible coatings enriched with four different dietary fibers (apple fiber, orange fiber, inulin and oligofructose) on microbiological, nutritional, physico-chemical and sensorial properties of ready-to-eat fresh blueberries stored for 18 days at 5 °C.

RESULTS

The most encouraging results were found for CH coatings (with and without fibers) which significantly inhibited the growth of mesophilic bacteria and yeasts/molds (reductions up to 1.9 log CFU g^-1 ), reduced decay rate by more than 50%, enhanced antioxidant properties, retained fruit firmness, delayed off-odor development and improved overall visual quality of blueberries. Oligofructose and orange fiber added to CH coatings enhanced antioxidant properties of fruits and allowed higher reductions in yeast/mold counts compared to the use of CH alone. CH-based coatings enriched with inulin, oligofructose and apple fiber extended sensory shelf life of blueberries by 6 days. AL coatings (with and without fiber) allowed delaying fungal decay and also retaining antioxidant properties but did not improve the microbiological and sensory quality of fruits.

CONCLUSION

The results proved that fiber-enriched CH treatments allowed the maintenance of freshness and the improvement of the quality of ready-to-eat blueberries. It might be an interesting option to offer consumers a healthy product with prebiotic potential and an extended shelf life. © 2017 Society of Chemical Industry.

Use of propolis in the sanitization of lettuce

The present study aimed to determine the effectiveness of propolis in reducing the microbial load in ready-to-eat (RTE) and fresh whole head (FWH) lettuces (Lactuca sativa L.) type Batavia. Two sanitizing solutions were employed: sodium hypochlorite (SH) and propolis (PS), during 15 and 30 min. Tap water (TW) was used as a control. Regarding the mean reduction on aerobic mesophiles, psychrotrophic and fecal coliforms, the SH and PS treatments showed the same pattern of variation. In all cases, PS was slightly more effective in the microbiological reduction in comparison with commercial SH. Reductions between two and three log cycles were obtained with PS on aerobic mesophiles and psychrotrophic counts. The information obtained in the present study can be used to evaluate the potential use of propolis as product for sanitizing other vegetables and for developing other food preservation technologies, with impact on human health.