No abstract

Shelf life of pasteurized milk in Brazil ranges from 3 to 8 d, mainly due to poor cold chain conditions that prevail throughout the country and subject the product to repeated and/or severe temperature abuse. This study evaluated the influence of storage temperature on the microbiological stability of homogenized whole pasteurized milk (75 degrees C/15 s) packaged in high-density polyethylene (HDPE) bottle and low-density polyethylene (LDPE) pouch, both monolayer materials pigmented with titanium dioxide (TiO(2)). The storage temperatures investigated were 2, 4, 9, 14, and 16 degrees C. Microbiological evaluation was based on mesophilic and psychrotrophic counts with 7 log CFU/mL and 6 log CFU/mL, respectively, set as upper limits of acceptability for maintaining the quality of milk. The microbiological stability for pasteurized milk packaged in HDPE bottle and stored at 2, 4, 9, 14, and 16 degrees C was estimated at 43, 36, 8, 5, and 3 d, respectively. For milk samples packaged in LDPE pouch, shelf life was estimated at 37, 35, 7, 3, and 2 d, respectively. The determination of Q(10) and z values demonstrated that storage temperature has a greater influence on microbiological shelf life of pasteurized milk packaged in LDPE pouch compared to HDPE bottle. Based on the results of this study, HDPE bottle was better for storing pasteurized milk as compared to LDPE pouch.

The shelf life of fresh sugarcane juice is quite limited due to the high rates of microbiological and enzymatic reactions which take place after extraction. In order to evaluate the impact of pasteurization temperature on quality and stability of sugarcane juice with passion fruit pulp, nine batches of sugarcane juice with 4g/100g passion fruit pulp were processed at 85, 90 and 95 °C for 30 s, in triplicate. The pasteurized beverage was aseptically packaged in polyethylene terephthalate (PET) bottles and stored at 7 °C in the dark. The beverage was characterized by physicochemical tests. Activities of polyphenol oxidase (PPO) and peroxidase (POD) were determined before and after processing. Coliforms and Salmonella tests were carried out to assure the beverage´s microbiological safety. Color parameters were measured in the processed juice throughout the storage period. Fifty panelists evaluated the beverage's appearance, aroma, flavor, and overall impression using seven-point hedonic scale tests. Sensory stability was estimated by considering score averages above four and percentages of acceptance above 60%. The pH, soluble solids and titratable acidity of end product ranged from 3.96 to 4.19, 19.7 to 20.1 ºBrix, and 0.163 to 0.175 g/100g citric acid, respectively. The three processing binomials were effective for PPO inactivation; however, complete POD inactivation was reached at 95 °C/30 s only. The estimated sensory shelf-lives for sugarcane juice with passion fruit pulp processed at 85, 90 and 95 °C/30 s were 30, 40 and 50 days, respectively. Thus, the increase of pasteurization temperature had a positive effect on product's stability.Index terms: Shelf-life, hurdle technology, aseptic filling. RESUMOO tempo de vida útil do caldo de cana in natura é bastante limitado em virtude das elevadas taxas de reações microbiológicas e enzimáticas que ocorrem na bebida após a sua extração. Visando à avaliação do impacto da temperatura de pasteurização na qualidade e na estabilidade de caldo de cana acidificado, processaram-se nove lotes de caldo adicionados de polpa de maracujá. Os lotes foram pasteurizados a 85, 90 e 95 °C por 30 s, em triplicata, envasados assepticamente em garrafas de polietileno tereftalato (PET) e estocados a 7 °C, na ausência de luz. Testes físico-químicos foram realizados para caracterizar a bebida. Determinaram-se as atividades de polifenoloxidase (PPO) e peroxidase (POD) antes e após o processamento. Contagens de coliformes e análise de Salmonella foram realizadas para garantir a segurança microbiológica da bebida. Parâmetros de cor foram medidos durante o período de estocagem. Cinquenta provadores avaliaram a aparência, o aroma, o sabor e a aceitação global da bebida por meio de testes de escala hedônica de sete pontos. A estabilidade sensorial foi estimada considerando-se médias de notas acima de quatro e porcentagens de aceitação superiores a 60%. As médias dos valores de pH, de sólidos solúveis e de acidez titulável do produto final variaram entre 3,96 e 4,19;19,7 e 20,1 ºBrix, e 0...

This study was undertaken to evaluate a pilot plant designed for sugarcane juice processing. The juice was extracted in an electric mill and acidified with citric acid until the pH of 4.3. Next, it was pasteurized in a plate heat exchanger at 95°C/30 sec, cooled to 10°C before being filled into a plastic bottle and induction sealed. Product filling was performed in an ISO class 5 unidirectional air-flow cabins. Three batches of acidified sugarcane juice were produced. The qualities of the raw material, rinse water of the processing and filling line, packaging and end product were all microbiologically evaluated. Hedonic scale tests were used to evaluate the sensory acceptance of the product. The total mean counts in mesophilic culture of molds and yeasts from the natural, fresh sugarcane juice were (6.26 and 5.20) log CFU/mL, respectively. These mean counts, in both rinse water samples of the processing line and the bottles, were lower than 1 log CFU/mL. The mean counts of molds and yeasts in acidified and pasteurized sugarcane juice were (2.63 and lower than 1) log CFU/mL, respectively. The findings indicated that the procedures that were evaluated met standards for acidified sugarcane juice to be produced then stored under refrigeration.