Patrícia Campos Bernardes

Removal of Salmonella enterica Enteritidis and Escherichia coli from green peppers and melons by ultrasound and organic acids.

The aim of this study was to evaluate the effectiveness of ultrasound treatment combined with organic acids in the decontamination step for green peppers and melons. The influence of the surface roughness of the peppers and melons on bacterial adhesion was evaluated, as measured using a profilometer. The adhesion of Salmonella enterica serovar Enteritidis and Escherichia coli to the green pepper and melon surfaces was also evaluated by measuring the hydrophobicity of the microorganisms and the surfaces. The bacteria that adhered to the surface of green peppers and melons was quantified by plate count and visualized by scanning electron microscopy. In addition, the efficiency of ultrasound and organic acids to remove bacteria from the pepper and melon surfaces was examined. The average roughness (Ra) of the green peppers (13.0±2.7 nm) was significantly different (p>0.05) from the melons (33.5±7.9 nm). Adherence of S. Enteritidis and E. coli are thermodynamically unfavorable for both surfaces studied (∆G(adhesion)>0). Despite these data, good adhesion occurred on both surfaces. The number of bacteria on green pepper slices was 7.3 and 7.0 log CFU/cm(2) for E. coli and S. enterica Enteritidis, respectively. For melon surfaces, the number of bacteria was 7.0 and 6.9 log CFU/cm(2) for E. coli and S. Enteritidis, respectively. The greater adherence of both bacteria on the green peppers can be explained by its hydrophobic surface; the hydrophilic surfaces of melons resulted in lower adherence. These results suggest that the adhesion observed in this experiment is a multifactorial process. Among the treatments evaluated for green peppers, a higher removal of pathogens was observed after use of a combination of ultrasound and 1% lactic acid; this treatment reduced E. coli and Salmonella by 2.9 and 2.8 log CFU/cm(2), respectively. For melons, the combination of ultrasound and lactic acid showed a reduction of 2.5 and 3.1 log CFU/cm(2) for E. coli and S. Enteritidis, respectively. These results indicate that it is possible to replace the chlorinated compounds that are commonly used to sanitize fruits and vegetables. These results confirm that ultrasound, an emerging technology for food processing applications, could enhance the microbial safety of fresh produce.

Ultrasound improves chemical reduction of natural contaminant microbiota and Salmonella enterica subsp. enterica on strawberries.

New sanitization methods have been evaluated to improve food safety and food quality and to replace chlorine compounds. However, these new methods can lead to physicochemical and sensory changes in fruits and vegetables. The present study evaluated the effects of acetic acid, peracetic acid, and sodium dodecylbenzenesulfonate isolated or combined with 5min of ultrasound treatment (40kHz, 500W) on strawberry quality over 9days of storage at 8°C. The strawberry natural contaminant microbiota (molds and yeasts, mesophilic aerobic and lactic acid bacteria), physicochemical quality (pH, total titratable acidity, total soluble solids, vitamin C, and color), sensory quality (triangle test) and inactivation of Salmonella enterica subsp. enterica intentionally inoculated onto strawberries were analyzed. Ultrasound increased the effect of all chemical compounds in the reduction of aerobic mesophilic, molds and yeasts. The best treatment for those groups of microorganisms was ultrasound combined with peracetic acid (US+PA) that reduced 1.8 and 2.0logcfu/g during 9days of storage. Bactericidal effect of peracetic acid was also improved by ultrasound inactivation of S. enterica, reaching a decimal reduction of 2.1logcfu/g. Moreover, synergistic effects were observed in contaminant natural microbiota inactivation for all tested compounds during storage, without any major physicochemical or sensory alteration to the strawberries. Therefore, ultrasound treatment can improve the effect of sanitizers that are substitutes of chlorine compounds without altering the quality of strawberries during storage. Acetic acid (PubChem CID: 176); Peracetic acid (PubChem CID: 6585); Sodium dodecylbenzenesulfonate (PubChem CID: 18372154).

Ultrasound improves antimicrobial effect of sodium dichloroisocyanurate to reduce Salmonella Typhimurium on purple cabbage

The consumers interest in ready-to-eat, fast-ready, nutritious and fresh foods is a major challenge for the food industry. Thus, studies on new sanitization methods are relevant. The effect of Sodium Hypochlorite (SH), Benzalkonium Chloride (BC), and Sodium Dichloroisocyanurate (SD) isolated or combined with Ultrasound (US) in purple cabbage quality over 7 days of storage at 8 ± 1 °C was evaluated. The natural microbiota (mesophilic aerobic bacteria, lactic acid bacteria and coliforms), intentionally inoculated Salmonella Typhimurium, physicochemical quality (anthocyanins, pH, total titratable acidity, instrumental color and mass loss) and sensorial quality (multiple comparison test and visual sensory acceptance) were analyzed. The best treatments for natural microbiota reduction were BC and US + BC, which in general reduced between 1.9 and 3.2 log cfu/g. US improved (p < .05) the effect of SD reducing almost 4 log cycles in the population of S. Typhimurium adhered to cabbage. The treatments with benzalkonium chloride resulted in important physicochemical changes in cabbage. The treatments SD and US + SD did not alter the physicochemical and sensorial characteristics of purple cabbage. Therefore, ultrasound combined with sodium dichloroisocyanurate is a promising alternative for the reduction of microbiological contaminants of purple cabbage without physicochemical, sensory and anthocyanin content loss.

CONFORMITY OF REFRIGERATED RAW MILK FROM FAMILY PRODUCTION UNITS OF SOUTHERN ESPÍRITO SANTO

Dairy farming is an important activity in Brazil and Espírito Santo state, with small properties accounting for 80% of production. Despite of this economic importance, data about quality of the milk produced and the hygienic-sanitary conditions are still scarce. Then, the objective of this study was to evaluate the characteristics of refrigerated raw milk produced in family production units in southern Espírito Santo to verify compliance with Brazilian legal standards. Three collections were carried out in 29 community expansion tanks, for a total of 87 samples of refrigerated raw milk. Analysis of standard plate count (SPC), psychrotrophic bacteria count (PBC), somatic cell count (SCC), titratable acidity, density, fat, total dry extract (TDE), non-fat dry extract (NFDE), residues of antibiotics (β-lactam and tetracycline), cadmium and lead levels were performed. Of the 87 samples, 66% presented non-standard values for SPC, and 38% had non-standard values for SCC. Eighty five percent of the samples presented non-standard results for NFDE, 10.3% for density and 2.3% for titratable acidity. All samples complied with the legislation regarding residues of antibiotics, Cd and Pb levels. These results indicated failures in the raw milk obtainment and storage chain from family production units of southern Espírito Santo, Brazil.