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dc.contributor.authorYang, Qiwei
dc.date.accessioned2020-02-20T22:07:45Z
dc.date.available2020-02-20T22:07:45Z
dc.date.issued2018
dc.identifier.urihttp://hdl.handle.net/10179/15215
dc.descriptionPossibly copyrighted Figures remain as their sources may not be accessible.en_US
dc.description.abstractMost gluten free (GF) products on the market are described as bland with poor mouth feel and are considered low quality in terms of texture due to lack of gluten, which has positive effects on the texture and appearance of cereal bakery products. The application of sourdough is a recent development in improving the quality of GF bread due to its efficiency and low-cost. This study aims to understand the fermentation of GF rice flour mix used to improve the quality of rice sourdough bread. Rice sourdough samples from three stages of fermentation mother sourdough (MSD), dough before proofing (DBP) and dough after proofing (DAP) and sourdough bread were characterised for their acidity, soluble sugars and organic acids content and total free amino acid content. Sourdough breads were also tested for their texture and colour. Yeasts and LAB colonies were enumerated from sourdough samples and isolates of LAB and yeasts were identified using API test kits (API 50 CHL for LAB and API 32 C for yeasts) and sequenced using 16S metagenetics for LAB and ITS region for yeasts. Due to the metabolic activities of sourdough lactic acid bacteria (LAB) and yeasts, dough acidity increased significantly (p>0.05) and total free amino acid content decreased during fermentation. Compared to unleavened rice bread, the final rice sourdough bread had a softer, more elastic, less crumbly and chewier crumb and its crust colour was more similar to unleavened wheat bread. Mean LAB counts in MSD, DBP and DAP were 8.6 log CFU/g, 7.9 log CFU/g and 8.5 log CFU/g, respectively; while yeast counts were 5.4 log CFU/g, 6.4 log CFU/g, and 6.7 log CFU/g, respectively. LAB counts increased significantly (p<0.05) during proofing but yeasts did not exhibit significant growth (p>0.05). Dominant LAB and yeasts responsible for the fermentation of rice sourdough were of the genus Lactobacillus and S. cerevisiae. LAB isolates were identified as Lactobacillus plantarum CIP 102980 and Lactobacillus fermentarum DSM 10667 and yeast colonies as S. cerevisiae CBS 1171.en_US
dc.language.isoenen_US
dc.publisherMassey Universityen_US
dc.rightsThe Authoren_US
dc.subjectSourdough breaden_US
dc.subjectNew Zealanden_US
dc.subjectRice flouren_US
dc.subjectFermentationen_US
dc.subjectLactic acid bacteriaen_US
dc.subjectYeasten_US
dc.titleDominant lactic acid bacteria and yeasts in rice sourdough produced in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Albany, New Zealanden_US
dc.typeThesisen_US
thesis.degree.disciplineFood Technologyen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Food Technology (MFoodTech)en_US
dc.subject.anzsrc300607 Food technologyen


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