Distribution and stability of aflatoxin M-1 during processing and storage of Minas Frescal cheese

Aflatoxin M-1 (AFM(1)) is a hepatocarcinogen found in milk of animals that have consumed feeds with aflatoxin B-1. The carry-over of AFM(1) from milk to Minas Frescal cheese produced with or without starter cultures was determined. 40 L of milk were divided into 10 L each and assigned to the following treatments for cheese manufacture: 0.250 rig AFM(1) mL(-1), 0.500 rig AFM(1) mL(-1), 0.250 ng AFM(1) mL(-1) + starter, 0.500 ng AFM(1) mL(-1) + starter. Quantification of AFM(1) was achieved by high performance liquid chromatography. The carry-over of AFM(1) from milk to cheese ranged from 30.64% to 42.26%. There was no effect of storage time on AFM(1). Milk with AFM(1) in levels studied may concentrate the toxin in Minas Frescal cheese, but at concentrations below the Brazilian tolerance limit. The addition of starter cultures did not influence concentration or stability of the AFM(1) in cheese over 30 days storage. (C) 2011 Elsevier Ltd. All rights reserved.

Effect of liposome-encapsulated nisin and bacteriocin-like substance P34 on Listeria monocytogenes growth in Minas frescal cheese

The efficacy of liposome-encapsulated nisin and bacteriocin-like substance (BLS) P34 to control growth of Listeria monocytogenes in Minas frescal cheese was investigated. Nisin and BLS P34 were encapsulated in partially purified soybean phosphatidylcholine (PC-1) and PC-1-cholesterol (7:3) liposomes. PC-1 nanovesicles were previously characterized. PC-1-cholesterol encapsulated nisin and BLS P34 presented, respectively, 218 nm and 158 nm diameters, zeta potential of -64 mV and -53 mV, and entrapment efficiency of 88.9% and 100%. All treatments reduced the population of L monocytogenes compared to the control during 21 days of storage of Minas frescal cheese at 7 degrees C. However, nisin and BLS P34 encapsulated in PC-1-cholesterol liposomes were less efficient in controlling L monocytogenes growth in comparison with free and PC-1 liposome-encapsulated bacteriocins. The highest inhibitory effect was observed for nisin and BLS P34 encapsulated in PC-1 liposomes after 10 days of storage of the product The encapsulation of bacteriocins in liposomes of partially purified soybean phosphatidylcholine may be a promising technology for the control of food-borne pathogens in cheeses. (C) 2012 Elsevier B.V. All rights reserved.

On the implementation of good manufacturing practices in a small processing unity of mozzarella cheese in Brazil

This study reports the implementation of GMPs in a mozzarella cheese processing plant. The mozzarella cheese manufacturing unit is located in the Southwestern region of the state of Parana, Brazil, and processes 20,000 L of milk daily. The implementation of GMP took place with the creation of a multi-disciplinary team and it was carried out in four steps: diagnosis, report of the diagnosis and road map, corrective measures and follow-up of GMP implementation. The effectiveness of actions taken and GMP implementation was compared by the total percentages of non-conformities and conformities before and after implementation of GMR Microbiological indicators were also used to assess the implementation of GMP in the mozzarella cheese processing facility. Results showed that the average percentage of conformity after the implementation of GMP was significant increased to 66%, while before it was 32% (p < 0.05). The populations of aerobic microorganisms and total coliforms in equipment were significantly reduced (p < 0.05) after the implementation of GMP, as well as the populations of total coliforms in the hands of food handlers (p < 0.05). In conclusion, GMP implementation changed the overall organization of the cheese processing unity, as well as managers and food handlers' behavior and knowledge on the quality and safety of products manufactured. (C) 2011 Elsevier Ltd. All rights reserved.

Probiotic cheese attenuates exercise-induced immune suppression in Wistar rats

Intense physical activity results in a substantial volume of stress and hence a significant probability of immunosuppression in athletes, with milk proteins being, perhaps, the most recommended protein supplements. Consumption of a probiotic cheese can attenuate immune suppression induced by exhausting exercise in rats. A popular Brazilian fresh cheese (Minas Frescal cheese) containing Lactobacillus acidophilus LA14 and Bifidobacterium longum BL05 was fed for 2 wk to adult Wistar rats, which then were brought to exhaustion on the treadmill. Two hours after exhaustion, the rats were killed and material was collected for the determination of serum uric acid, total and high-density lipoprotein cholesterol fraction, total protein, triacylglycerols, aspartate aminotransferase, alanine aminotransferase, creatine kinase, and blood cell (monocyte, lymphocyte, neutrophil, and leukocyte) counts. Exercise was efficient in reducing lymphocyte counts, irrespective of the type of ingested cheese, but the decrease in the group fed the probiotic cheese was 22% compared with 48% in the animals fed regular cheese. Monocyte counts were unaltered in the rats fed probiotic cheese compared with a significant decrease in the rats fed the regular cheese. Most importantly, ingestion of the probiotic cheese resulted in a >100% increase in serum high-density lipoprotein cholesterol and a 50% decrease in triacylglycerols. We conclude that probiotic Minas Reseal cheese may be a viable alternative to enhance the immune system and could be used to prevent infections, particularly those related to the physical overexertion of athletes.

Dried Tomato-Flavored Probiotic Cream Cheese with Lactobacillus paracasei

A dried tomato-flavored probiotic cream cheese (P) containing Lactobacillus paracasei Lpc-37 was developed for the purpose of this study. The same product, but without probiotic addition (C) was used as control. Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris were used as lactic starter cultures. Chemical composition analyses and sensory tests were performed on days 1 and 7, respectively. Titratable acidity, pH value and L. paracasei population were determined every 7 d during the refrigerated storage (21 d) of the cream cheeses. The experiment and analyses were performed in triplicate, using standard methods. Probiotic population remained greater than 10(7) CFU/g throughout the storage period, thereby characterizing the product as potentially probiotic. Cream cheeses C and P did not differ on the sensory tests, both obtaining good overall acceptance by the consumers, of which 82.6% stated that they certainly or probably would buy the product.

Application of bacteriocinogenic Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch in the control of Listeria monocytogenes in fresh Minas cheese

Several strains of Enterococcus spp. are capable of producing bacteriocins with antimicrobial activity against important bacterial pathogens in dairy products. In this study, the bacteriocins produced by two Enterococcus strains (Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch), isolated from cheeses, were characterized and tested for their capability to control growth of Listeria monocytogenes 426 in experimentally contaminated fresh Minas cheese during refrigerated storage. Both strains were active against a variety of pathogenic and non-pathogenic microorganisms and bacteriocin absorption to various L. monocytogenes, Enterococcus faecalis ATCC 19443 and Lactobacillus sakei ATCC 15521 varied according to the strain and the testing conditions (pH, temperature, presence of salts and surfactants). Growth of L. monocytogenes 426 was inhibited in cheeses containing E. mundtii CRL35 up to 12 days at 8 degrees C, evidencing a bacteriostatic effect. E. faecium ST88Ch was less effective, as the bacteriostatic affect occurred only after 6 days at 8 degrees C. In cheeses containing nisin (12.5 mg/kg), less than one log reduction was observed. This research underlines the potential application of E. mundtii CRL35 in the control of L. monocytogenes in Minas cheese. (c) 2012 Elsevier Ltd. All rights reserved.