Effect of cooking and cooling time-temperature on the survival and viability of e.coli in bulk ‘dalca’ serving

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dc.contributor.authorAbdul Hadi, Arnieyantie
dc.date.accessioned2014-11-03T02:09:54Z
dc.date.available2014-11-03T02:09:54Z
dc.date.issued2009
dc.descriptionMasteren_US
dc.description.abstractThe occurrence of food poisoning outbreaks in food service establishments would frequently involve food prepared in bulk. This research was performed to study the physicochemical characteristics of ‘dalca’, its heating and cooling pattern during preparation, the survival curve of bacteria and pathogen during heating and cooling, the lethality of target organism, as well as simulation of temperature control during serving of potentially hazardous food. ‘Dalca’ which represents one of the Malaysian favorite cuisines were used as food model while pathogenic E.coli strain 0157:H7 as target organism. Approximately 10 kg ‘dalca’ was prepared according to original recipe with some modification. Cooked ‘dalca’ (boiled for 60 min) gave final yield of 9.61± 0.10 kg, pH 5.23± 0.13, viscosity 3.64±0.25 pa.s and Aw 0.975± 0.002 with 1.86±0.08% ash and 65.58±0.58% moisture, 19.01±0.83% fat, 5.52±0.54% protein and 8.03±0.21% total carbohydrates. These physicochemical characteristics indicated that ‘dalca’ is a potentially hazardous food. The initial microbial load of raw ‘dalca’ was 5.92-5.96 log CFU/g which however did not exceed the spoilage index. Coliform and Faecal coliform count were 1500-2400 and 400-700 MPN/100g respectively, not exceeding the microbiology standard (Akta makanan dan Peraturan Makanan pindaan 2004). Survival curve during production of bulk ‘dalca’ (~10 kg) at different boiling period (0, 20 and 60 minutes) demonstrated the decrease in bacteria and E.coli 0157:H7 numbers with increase in process time-temperature. The duration of 60 min boiling time gave the lowest number of bacteria present after cooking (<30) with the lowest number of proliferation after heating (<30). E.coli 0157:H7 was destroyed after arriving at internal temperature of 710C. D-value for 670C, 690C and 710C is 6.73 min, 4.56 min and 1.41 min respectively while z value was 5.920C. The lethality (F) of E.coli 0157:H7 in ‘dalca’ with reference temperature at 710C, z value = 5.920C and D value = 1.41 min by referring to the decrease in cell population for 0, 20 and 60 min was 7.48± 1.0 min or equal to 5.3 log destruction whereas by using time-temperature integration process, the F-value was 7.25±1.0 min or equals to 5.14 log reduction. Both F- value obtained exceeded 5D destruction of pathogen recommended by USDA (2006). The study on cooling pattern showed similar growth curve of bacteria and E.coli 0157:H7 during cooling at room temperature (±280C) in bulk (~10 kg) or smaller portion (~4.8 kg) with increase in bacteria and E.coli 0157:H7 numbers occurring rapidly when approaching room temperature. Cooling at 30C demonstrated the decrease of proliferation of bacteria and E.coli 0157:H7 when approaching 30C. However, the slower temperature decrease during cooling of ~10 kg dalca results in higher bacterial numbers compared to smaller portion at the end of cooling process. Simulation study in the cafeteria without temperature control promoted the growth of both bacteria and E.coli 0157:H7 to 1 log10 and 0.39 log CFU/g respectively within the serving period and conversely with temperature control.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/208
dc.language.isoenen_US
dc.subjectIndustrial technologyen_US
dc.subjectCookingen_US
dc.subjecte.colien_US
dc.titleEffect of cooking and cooling time-temperature on the survival and viability of e.coli in bulk ‘dalca’ servingen_US
dc.typeThesisen_US
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