Sanitização por ultrassom e agentes químicos no processamento mínimo de hortaliças

• Ano de defesa: 2009
• Autor(a) principal: José, Jackline Freitas Brilhante de São
• Orientador(a): Vanetti, Maria Cristina Dantas
• Banca de defesa: Andrade, Nélio José de , Fantuzzi, Elisabete
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Microbiologia Agrícola
• Departamento: Associações micorrízicas; Bactérias láticas e probióticos; Biologia molecular de fungos de interesse
• País: BR
• Palavras-chave em Português: Qualidade microbiológica; Processamento mínimo; Ultrassom; Sanitização
• Palavras-chave em Inglês: Microbiological quality; Minimally processed; Ultrasound; Sanitization
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS::MICROBIOLOGIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/5315

This study aimed to evaluate the use of ultrasound in sanitization of minimally processed vegetables. Watercress, parsley, strawberry and cherry tomatoes were subjected to with a 10 minute ultrasound (45 kHz) treatment, with or without chemical agents. Sodium dichloroisocyanurate at 50 mg.L-1 and 200 mg.L-1, 5% hydrogen peroxide peracetic acid at 40 mg.L-1 and chlorine dioxide were used as chemical agents. The reduction of the initial contamination of vegetables by aerobic bacteria plate count and moulds and yeasts was determinate. After sanitization, changes in pH value, color and odor were evaluated. The treatment which resulted in greater contaminant removal was evaluated for the cherry tomato intentionally contaminated with Salmonella Typhimurium ATCC 14028 cells at concentrations ranging from 106 to 107 CFU. L-1. The contaminated tomatoes were incubated for 48 hours to allow cell adhesion and then subjected to sanitization treatments with chlorinated water at 50 and 200 mg.L-1, peracetic acid at 40 mg L-1, ultrasound (45 kHz) and ultrasound combined with peracetic acid at 40 mg L-1. The quantification of the adhered cells was performed by counting colonies on Salmonella Shigella (SSA) agar. Salmonella cells adhered to the surface of cherry tomatoes was observed on an epifluorescence microscope and scanning electron microscope. All comparisons were made by ANOVA (p <0.05). Then, the difference between the averages were analyzed by means of the Tukey test (p <0.05). Sodium dichloroisocyanurate at 200 mg.L-1 and chlorine dioxide at 10 mg.L-1 combined with ultrasound treatment promoted greater reduction in the initial count of aerobic bacteria if compared to the sum of the reductions of the treatments alone, which indicated a synergistic effect. It was found that the combination treatment with peracetic acid at 40 mg.L-1 and ultrasound allowed a reduction of 4.5 to 6.5 log CFU.g-1 and 3.5 to 4.5 log CFU.g-1 on the population of aerobic bacteria and moulds and yeasts, respectively. Despite the considerable reduction on microbial populations, this sanitizer, combined or not with ultrasound, led to color changes in the strawberries. Ultrasound treatment and peracetic acid at 40 mg L-1 showed a reduction of 3.88 log CFU. g-1 of Salmonella Typhimurium ATCC 14028 adhered to the surface of cherry tomatoes. Ultrasound treatments for a period of 10, 20 and 30 minutes reduced CFU. g-1 to 0.83, 1.22 and 1.73 log (p <0.05), respectively. The reduction of adhered cells was confirmed by epifluorescence microscopy and scanning electron microscopy. The results indicate the importance of the use of ultrasound as an auxiliary technology in sanitization step of the vegetables studied.