ABSTRACT
RESUMEN El deterioro microbiológico de alimentos conduce a productos no aptos para consumo, y su descarte, a importantes pérdidas económicas para la industria alimenticia. Durante su almacenamiento, los alimentos frescos representan nichos atractivos para la supervivencia y el crecimiento de microorganismos indeseables. En productos lácteos, la presencia de alterantes o patógenos bacterianos está mejor documentada que la de mohos y levaduras. Estos productos son menos proclives al deterioro por mohos que otros, como frutas y verduras, debido a su almacenamiento refrigerado, su elaboración a partir de leche tratada térmicamente y, para fermentados, a la microbiota dominante, que acidifica el medio. Sin embargo, incluso quesos y yogures pueden sufrir deterioro por mohos. Este trabajo presenta casos atípicos de muestras de yogur con desarrollo de mohos gasógenos y bacterias del géneroGluconobactercomo microorganismos alterantes no reportados previamente como tales en leches fermentadas argentinas. Los organismos alterantes «clásicos¼ de yogur fueron siempre levaduras y, en otros países, mohos del géneroAspergillus.
ABSTRACT Microbial food alterations lead to unfit products for consumption, and their discarding, to significant economic losses for the food industry. During storage, fresh foods offer available niches for the survival and growth of undesirable microorganisms. In dairy products, data regarding spoilage and/or pathogenic bacteria is better documented than those for molds and yeasts. Dairy products are less susceptible to mold's contamination than products such as fruits and vegetables, due to their refrigerated storage; their elaboration from heat-treated milk and, for fermented ones, the dominant microbiota that acidifies the medium. However, even cheeses and yogurts may be susceptible to mold contamination. Atypical cases of yogurt samples containing spoilage microorganisms not previously reported (molds producing gas and bacteria of the genusGluconobacter) in Argentinean fermented milks are presented here. For yogurt, in particular, the "classic" altering organisms were always being yeasts, and in other countries, molds belonging to the genusAspergillus.
Subject(s)
Yogurt , Gluconobacter , Bacteria , Yeasts , Yogurt/analysis , Food Microbiology , FungiABSTRACT
This work is aimed to obtain nanocomplexes based on egg white protein nanoparticles (EWPn) and bioactive compounds (BC), carvacrol (CAR), thymol (THY) and trans-cinnamaldehyde (CIN), and evaluate their application as antifungal edible coatings on preservative-free breads. The nanocomplex formation was studied through stoichiometry, affinity, colloidal behavior, morphology, and encapsulation efficiency (EE, %). Rounded-shape nanocomplexes with particle sizes < 100 nm were obtained. The EE values were similar for all BC (>83%). Furthermore, the in vitro antifungal activity of the nanocomplexes was verified using the Aspergillus niger species. The nanocomplexes were applied as coatings onto the crust of preservative-free breads, which were stored for 7 days (at 25 °C). The coatings had no impact on the physicochemical properties of the bread loaves (moisture, aw, texture, and color). Finally, the coatings based on EWPn-THY and EWPn-CAR nanocomplexes showed higher antifungal efficacy, extending the bread shelf life after 7 days.
Subject(s)
Edible Films , Nanoparticles , Antifungal Agents/pharmacology , Bread , Egg Proteins , Food Preservatives/pharmacologyABSTRACT
Microbial food alterations lead to unfit products for consumption, and their discarding, to significant economic losses for the food industry. During storage, fresh foods offer available niches for the survival and growth of undesirable microorganisms. In dairy products, data regarding spoilage and/or pathogenic bacteria is better documented than those for molds and yeasts. Dairy products are less susceptible to mold's contamination than products such as fruits and vegetables, due to their refrigerated storage; their elaboration from heat-treated milk and, for fermented ones, the dominant microbiota that acidifies the medium. However, even cheeses and yogurts may be susceptible to mold contamination. Atypical cases of yogurt samples containing spoilage microorganisms not previously reported (molds producing gas and bacteria of the genus Gluconobacter) in Argentinean fermented milks are presented here. For yogurt, in particular, the "classic" altering organisms were always being yeasts, and in other countries, molds belonging to the genus Aspergillus.
Subject(s)
Gluconobacter , Yogurt , Bacteria , Food Microbiology , Fungi , Yeasts , Yogurt/analysisABSTRACT
Microbial contamination is a problem in food industry. The effects produced by the metabolic activity of yeasts are diverse. If they are found in high numbers it might affect the organoleptic quality of the product. Zygosaccharomyces is the most frequent contaminant genus in sweetened juices that are not properly processed and stored. The aim of this work was to compare the action of five commercial sanitizers against isolates of Z. rouxii and to determine appropriate concentrations and time of action for the inactivation. Peracetic acid, monochloramine, iodophor and quaternary ammonium compounds were evaluated on different surfaces (stainless steel, plastic and glass) at room temperature for 30 and 60 s. It was possible to achieve a 99.99 of death Efficiency corresponding to 4 log10 of reduction for a contact time of 60 s for 0.5% (v/v) of peracetic acid, monochloramines and 0.5% (w/v) of iodophors, 1% for compound with a base of 8% (v/v) of benzyl chloride and 7.5% (v/v) of glutaraldehyde and 5% for sodium hypochlorite (55 g/L active compound). Stainless steel was successfully sanitized with all the compounds tested, and then it would be the most appropriate for the food industry because this material is also highly resistant to abrasion, to impact and to different chemical treatments. In view of the great variety of sanitizing products, the selection of the best sanitizer will depend on efficiency, safety and cost.
