Edson Antônio Rios

Microbiota mesófila aeróbia contaminante do leite UHT

In 2011 the national production of ultra-high temperature milk (UHT) was 5.81 billion liters, corresponding to 78% of fluid milk consumed in Brazil. The present work aimed to study UHT milk contamination by mesophilic aerobes (MA), verifying the accordance with microbiological standards, classifying the groups found according to its morpho-tinctorial characteristics and discussing the methodology determined by Normative Instruction (NI) 62 from the Brazilian Ministry of Agriculture, Animal Husbandry and Supply. From 60 studied samples, 23 (38.3%) presented results above the 100 CFU/mL standard established by NI 370 for (MA). When B. sporothermodurans was considered, maximum counts raised 71.2% in whole milk samples, and 31.0% in skimmed milk samples. Regarding the higher dilutions inoculated that have shown growth, it was possible to isolate 462 colonies of (MA) that, in Gram coloration corresponded to 64.3% Gram positive bacteria and 9.5% Gram negative. Molds and yeasts added up to 26.2%. Among Gram positive, there was a prevalence of cocci, B. sporothermodurans , and other Gram positive bacilli. Among Gram negative, the coccobacilli and bacilli prevailed. Considering that the samples represent UHT milk from important industries of southern Brazil, the results demonstrate that 11 out of the 15 studied brands showed high counts of (MA) when compared to the established standards. Furthermore, among the groups of microorganisms found in the samples, especially heat sensitive Gram negative bacteria, indicates possible failures in milk processing and/or post-processing contamination.

Selection of Leuconostoc strains isolated from artisanal Serrano Catarinense cheese for use as adjuncts in cheese manufacture: Selection of Leuconostoc strains for use as adjuncts

BACKGROUNDnSerrano Catarinense cheese is a raw bovine milk cheese produced in the region of Santa Catarina, Brazil. Twelve representative strains of Leuconostoc isolated from 20 samples of this artisanal cheese were selected and submitted for evaluation of the acidifying, proteolytic, autolytic, aminopeptidase and lipolytic activities, NaCl and acid resistance, production of dextran and biogenic amines and antimicrobial activity. The aim was to genetically and technologically characterize the Leuconostoc strains in order to use them in mixed starter cultures for cheese manufacture.nnnRESULTSnLeuconostoc mesenteroides subsp. mesenteroides was the species that accounted for the largest proportion of isolates of Leuconostoc genus. Two leuconostoc isolates stood out in the acidifying activity, with reduction in pH of 1.12 and 1.04u2009units. The isolates showed low proteolytic and autolytic activity. Most of the isolates were dextran producers, presented good resistance to the salt and pH conditions of the cheese and showed antimicrobial activity against cheese pathogen bacteria, and none of them produced biogenic amines.nnnCONCLUSIONnThese results allowed the selection of five strains (UEL 04, UEL 12, UEL 18, UEL 21 and UEL 28) as good candidates for use as adjunct cultures for cheese manufacture.