KINETICS OF PIGMENT DEGRADATION IN SLICED COOKED HAM

Sliced cooked ham was vacuum packaged and held in the dark at −15C. 10C, and 30C, and at 10C in the light, for up to 96 h. At 24 h intervals, samples were analyzed for pigment concentration by spectrophotometry. A decrease in pigment concentration was observed over time under all conditions. Pigment degradation increased at higher temperatures and with light exposure. Kinetic parameters were determined, indicating that pigment degradation follows first order kinetics and the temperature dependence of these reactions indicated an Arrhenius relationship. The activation energy was 3.3 kcal/mol. The visible spectra for the extracted pigments in cooked ham showed the typical pattern of nitrosylmyoglobin. Pigments extracted from ham displayed in the light had spectra with similar absorption maxima to those from those stored in the dark.     

Consumer acceptability and purchase intent of probiotic yoghurt with added glucose oxidase using sensometrics,artificial neural networks and logistic regression

This research aimed to identify the drivers of acceptance and purchase intent of a probiotic (Bifidobacterium longum BL05) nonflavoured yoghurt supplemented with glucose oxidase, and to model the consumers’ acceptability using sensometrics and artificial neural networks (ANN). Consumers (n = 100) evaluated the degree of liking of yoghurt assays in respect of appearance, aroma, taste, texture and overall linking. Sensometric techniques – multiple linear regression (MLR), partial least squares regression (PLS), principal component regression (PCR) – and ANN were used to model the overall liking. Sensory drivers of global acceptance and purchase intent were also determined using logistic regression (LR). Hierarchical cluster analysis (HCA) identified three consumer segments that presented differences in all sensory attributes evaluated (P < 0.05). The ANN model showed the best performance to predict overall liking, followed by the MLR, PLS and PCR, indicating that taste and texture were the most significant attributes impacting the yoghurts overall liking. In accordance with the logistic models, overall acceptance and purchase intent could be predicted with 81.94 and 85.49% accuracy, respectively. The logistic regression indicated that taste was the attribute that contributed significantly (P < 0.0001) to higher scores for purchase intent and was considered the driver of acceptance.     

Physicochemical and antioxidant properties of bovine caseinate hydrolysates obtained through microbial protease treatment

It is currently possible to obtain bioactive nutritional components through enzyme hydrolysis under well‐controlled and moderate conditions of pH and temperature. In this work, we aimed for the production and characterisation of bovine sodium caseinate (NaCAS) hydrolysates by means of an extracellular protease from Bacillus sp. P45. Antioxidant properties were evaluated through 2,2‐diphenyl‐1‐picrylhydrazyl and thiobarbituric acid reactive substances assays. A glucono‐δ‐lactone acid‐induced aggregation and gelation processes of the hydrolysates and their corresponding mixtures with NaCAS were also analysed. Hereby, we demonstrate that the presence of hydrolysates affects the kinetics of NaCAS aggregation processes but does not significantly alters the final state of the acid aggregates obtained.     

Development of goat cheese whey-flavoured beverages

Beverages made from goat cheese whey, flavoured with strawberry and peach pulp, were processed and submitted to physicochemical analysis and affective tests. The beverages exhibited similar values with respect to all the analyses of the proximate composition and little variation in pH and titratable acidity during refrigerated storage. They also showed low caloric value. For colour, aroma and consistency acceptability, there was no significant difference ( P > 0.05) among peach and strawberry flavoured samples. The flavour acceptability was higher for the strawberry beverage than for the peach one ( P = 0.05). A positive purchase intent for strawberry flavoured beverage was reported by 76% of the consumers, while 50% affirmed a similar intention for the peach-flavoured product. The beverages produced showed potential for commercialization, serving as an additional alternative product derived from goat milk, with minimal additional cost to the dairy plant.     

Comparison of Fascal cheese produced with natural,commercial or autochthonous cultures

Lactic acid bacteria were isolated from raw ovine milk and Fascal cheese and used as two alternative inoculants for production of this Brazilian cheese. Microbiological counts and moisture of these cheeses were comparable to those observed in cheese made with a commercial starter. All cheeses showed absence of Salmonella spp., tolerable counts of coliforms, but coagulase‐positive staphylococci counts exceeded the standard values. Cheeses produced with Lactobacillus plantarum LCN 28 and Lactobacillus rhamnosus LCN 43 showed better results than those observed for the other experimental combinations. Autochthonous cultures could be beneficial to the manufacture of high quality typical raw milk cheese.     

Proteolytic activity among psychrotrophic bacteria isolated from refrigerated raw milk

Psychrotrophic bacteria were isolated from refrigerated raw milk from a processing plant in Southern Brazil. Psychrotrophic counts were between 4.9 and 7.8 log cfu/mL, and 5.3 to 7.2 log cfu/mL, for samples collected at the truck and the milk storage silo, respectively. Among the bacterial isolates, 90% were Gram-negative. Most strains presented low proteolytic activity, but strains of Burkholderia cepacia, Klebsiella oxytoca and Aeromonas sp. showed higher than 20 U/mL on azocasein as substrate. Crude proteases from selected strains were resistant to conventional heat treatments and caused coagulation of UHT milk after 5 days storage at room temperature.     

Potentially probiotic açaí yogurt

The aim of this work was to evaluate the suitability of yogurt containing açaí pulp as a food carrier of probiotic cultures. Probiotic yogurts containing increasing amounts of açaí pulp (3, 5 and 7%) were processed and submitted to a physicochemical analysis and viable microbial count during refrigerated storage. In general, all the physicochemical parameters showed variations proportional to the amount of açaí pulp in the product formulation. Probiotic activity was verified throughout refrigerated storage for all the products, although there was a fall of one logarithmic cycle for both micro-organisms during this period (10⁷–10⁸ CFU/mL).     

ANTIMICROBIAL RESISTANCE IN SALMONELLA ENTERITIDIS ISOLATED FROM FOODS INVOLVED IN HUMAN FOODBORNE OUTBREAKS THAT OCCURRED IN THE SOUTH OF BRAZIL, 1999–2000

Antimicrobial resistance was determined for 73 isolates of Salmonella enteritidis isolated from foods involved in human foodborne outbreaks that occurred in the South of Brazil, from 1999 to 2000. The isolates were individually tested against 10 antimicrobial agents using a disc diffusion method. Most isolates were susceptible to all drugs tested. No S. enteritidis isolates were resistant to sulfamethoxazole/trimethoprim or chloramphenicol. The predominant resistance observed was to streptomycin (S) (37%), gentamicin (GEN) (13.7%) and nalidixic acid (NAL) (13.7%), while intermediate resistance was observed most often for tetracycline (53.4%), neomycin (NEO) (30.1%) and GEN (15.1%). Resistance was verified in 40 isolates (54%), which were grouped in 15 different patterns. Multiple resistance was presented in 17 (23%) of the isolates, and one isolate exhibited resistance to four drugs (NEO, kanamycin, S and NAL), demonstrating the involvement of multiresistant S. enteritidis strains with foodborne outbreaks.     

SURVIVAL OF ESCHERICHIA COLI, STAPHYLOCOCCUS AUREUS AND SALMONELLA ENTERITIDIS IN FROZEN CHICKEN HAMBURGER

The survival of food pathogens during frozen storage of chicken hamburgers was evaluated. Hamburgers were contaminated with Escherichia coli (ECHC), Staphylococcus aureus (SAFH) and Salmonella Enteritidis (SE86), separately, and stored at −18C for 28 days. Results demonstrated reductions of 0.63 log₁₀ cfu/g, 0.73 log₁₀ cfu/g and 0.27 log₁₀ most probable number/g in the populations of ECHC, SAFH and SE86, respectively. These microorganisms were also stored at −18C in 0.1% peptone water and presented significantly different reductions ( P <  0.05) when compared with frozen hamburgers, suggesting that components of chicken hamburger may exert a cryoprotective effect on microbial cells.

PRACTICAL APPLICATIONS

Even though Brazilian poultry meat industries present high levels of quality control, the presence of bacterial pathogens in hamburgers may occur. In Brazil, chicken hamburgers are frequently commercialized frozen, and it is well established that frozen temperatures are able to avoid microbial growth. However, frozen temperatures can also be able to inactivate part of the bacterial population, and the magnitude of its effect will vary according to the type of food and the process that it was submitted. This study evaluated the survival of Escherichia coli , Staphylococcus aureus , and Salmonella Enteritidis in frozen hamburgers, aiming to verify if this process could provide an additional margin of safety to this product.