Pengekstrakan dan sifat-sifat ekstrak yis daripada Candida Utilis
| dc.contributor.author | Rodiah, Mohd. Hassan | |
| dc.date.accessioned | 2014-11-14T07:58:06Z | |
| dc.date.available | 2014-11-14T07:58:06Z | |
| dc.date.issued | 2007 | |
| dc.description | Master | en_US |
| dc.description.abstract | The effects of enzymatic treatment and mechanical rupture carried out individually or in combination on the yield of yeast extract production from Candida utilis were studied in an attempt to obtain an optimum extraction process due to great potential of yeast extract as flavour enhancer in food industries. Candida utilis was cultured in 1500 mL pineapple waste medium in a 2.0 L benchtop fermentor for 30 h at 30 oC with agitation speed and aeration rate at 775 rpm and 2 L/min, respectively. In the enzymatic treatment, protease (Neutrase 1.5MG) and cellulase (Celluclast 1.5I FG) at two concentrations (0.5 % and 1.0 %, w/v) were used while for mechanical rupture, 5 g of glassbeads (0.25-0.65 mm) were added into 40 % (w/v) suspension of yeast cells. The extraction processes were carried out at 50 oC, 250 rpm for 24-42 h in an incubator shaker and samples were taken at 2-6 h intervals and analyzed for the percent of disrupted cells, total soluble proteins and solids. Optimum extraction was obtained from the enzymatic treatment using cellulase (0.5 %, w/v) aided with glassbeads for 18 h. The process resulted in higher soluble protein and solids, reaching 11.4 % (w/v) and 5.3 %, respectively with 90.1 % cells disrupted and the protein yield was 0.6 g/ L. The soluble extract was freeze-dried for characterization of chemical compositions and functional properties. The yeast extract in this study showed a high moisture content of 20.1 %, and thus low in Kjeldahl protein and ash content which were 39.6 % (dry weight) and 4.4 % (dry weight), respectively compared to the commercial yeast extracts (Maxarome®, Gistex® and yeast extract for microbiological media). The total and essential amino acids were 13.4 g/100 g and 5 g/100 g, respectively and were comparatively lower than the commercial yeast extracts. The yeast extract studied was found to have a prominent bitter taste compared to other flavours (sweet, MSG-like and no taste). However, the bitter taste was still the lowest if compared to the commercial yeast extracts. Contents of ribonucleotides, IMP (1.7 mg/g) and GMP (0.9 mg/g) were similar to that of Gistex® yeast extract while niacin, pyridoxine and riboflavine were 12.5, 0.09 and 0.07 g/ 100 g, respectively. The functional properties of the yeast extract in this study are comparable with those of commercial yeast extract which were indicated very good solubility, viscosity, emulsifying capacity, bulk density, colour and have good potential for application in food systems. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/529 | |
| dc.language.iso | en | en_US |
| dc.subject | Chemical science | en_US |
| dc.subject | Yeast extraction | en_US |
| dc.title | Pengekstrakan dan sifat-sifat ekstrak yis daripada Candida Utilis | en_US |
| dc.type | Thesis | en_US |
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