Kam, Shuk Fan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 124-134). / Abstracts in English and Chinese. / Abstract --- p.ii / Abstract in Chinese --- p.iv / Acknowledgements --- p.vi / List of Figures --- p.xi / List of Tables --- p.xii / Chapter Chapter 1 --- Literature Review --- p.1 / Chapter 1.1 --- Soybeans as Food --- p.1 / Chapter 1.1.1 --- Backgrounds --- p.1 / Chapter 1.1.2 --- Soybean Composition --- p.1 / Chapter 1.1.3 --- Diseases Prevention of Soybean Consumption --- p.3 / Chapter 1.1.4 --- Traditional Soyfoods --- p.3 / Chapter 1.2 --- Sufu --- p.5 / Chapter 1.2.1 --- Historical Information and Synonyms --- p.5 / Chapter 1.2.2 --- Features --- p.5 / Chapter 1.2.3 --- Manufacturing Techniques --- p.5 / Chapter 1.2.4 --- Types and Varieties of Sufu --- p.10 / Chapter 1.2.5 --- Compositional Changes during Fermentation and Ripening --- p.11 / Chapter 1.2.5.1 --- Proteins and Amino Acids --- p.11 / Chapter 1.2.5.2 --- Fats and Free Fatty Acids --- p.13 / Chapter 1.2.5.3 --- Carbohydrates --- p.14 / Chapter 1.2.5.4 --- Isoflavones --- p.15 / Chapter 1.2.6 --- Volatile Flavor Compounds --- p.15 / Chapter 1.3 --- Accelerated-Ripened Sufu --- p.17 / Chapter 1.4 --- Objectives of Project --- p.18 / Chapter Chapter 2 --- Contribution of Lipid to the Fatty Acids and Ethyl Esters in Model Plain Sufu --- p.20 / Chapter 2.1 --- Introduction --- p.20 / Chapter 2.2 --- Materials and Methodology --- p.23 / Chapter 2.2.1 --- Sufu Preparation --- p.23 / Chapter 2.2.1.1 --- Preparation of Tofu --- p.23 / Chapter 2.2.1.2 --- Preparation of Inoculum --- p.23 / Chapter 2.2.1.3 --- Spore Count in Spore Suspension --- p.24 / Chapter 2.2.1.4 --- Preparation of Pehtzes --- p.25 / Chapter 2.2.1.5 --- Brining and Ripening --- p.26 / Chapter 2.2.1.6 --- Sampling --- p.26 / Chapter 2.2.1.7 --- Free Fatty Acid Analysis --- p.26 / Chapter 2.2.1.7.1 --- Extraction --- p.26 / Chapter 2.2.1.7.2 --- Gas Chromatography-Mass Spectrometry Analysis (GC-MS) for Free Fatty Acid Analysis --- p.27 / Chapter 2.2.1.7.3 --- Compounds Identification and Quantification --- p.28 / Chapter 2.2.1.8 --- Ethyl Ester Analysis --- p.29 / Chapter 2.2.1.8.1 --- Extraction --- p.29 / Chapter 2.2.1.8.2 --- Gas Chromatography-Mass Spectrometry Analysis (GC-MS) for Ethyl Ester Analysis --- p.29 / Chapter 2.2.1.8.3 --- Compounds Identification and Quantification --- p.30 / Chapter 2.2.1.9 --- Enzymatic Activities --- p.30 / Chapter 2.2.1.9.1 --- Enzyme Extracts --- p.30 / Chapter 2.2.1.9.2 --- Lipase Activity Measurement --- p.31 / Chapter 2.2.1.9.3 --- Lipoxygenase Activity Measurement --- p.32 / Chapter 2.2.1.10 --- Determination of Peroxide Value --- p.33 / Chapter 2.2.1.11 --- pH Value Determination --- p.34 / Chapter 2.2.1.12 --- Moisture Content --- p.34 / Chapter 2.2.1.13 --- Statistical Analysis --- p.34 / Chapter 2.3 --- Results and Discussions --- p.35 / Chapter 2.3.1 --- Change of Free Fatty Acids with Sufu Processing Stage --- p.35 / Chapter 2.3.2 --- Change in Ethyl Esters with Sufu Processing Stage --- p.41 / Chapter 2.3.3 --- Activity of Lipase in the Sufu Enzyme Extracts --- p.47 / Chapter 2.3.4 --- Activity of Lipoxygenase in the Sufu Enzyme Extracts --- p.50 / Chapter 2.3.5 --- Lipid Oxidation determined by Peroxide Value --- p.50 / Chapter 2.3.6 --- pH Value Change during Sufu Production --- p.54 / Chapter 2.3.7 --- Moisture Content during Sufu Production --- p.56 / Chapter 2.3.8 --- Overall Discussions --- p.58 / Chapter 2.3.8.1 --- Lipolysis and Ester Synthesis --- p.58 / Chapter 2.3.8.2 --- Lipid Oxidation --- p.58 / Chapter 2.4 --- Conclusion --- p.61 / Chapter Chapter 3 --- A Study on Ripening Model Systems of Sufu --- p.63 / Chapter 3.1 --- Introduction --- p.63 / Chapter 3.2 --- Materials and Methodology --- p.68 / Chapter 3.2.1 --- Partial Purification Lipase from Mucor hiemalis --- p.68 / Chapter 3.2.1.1 --- Inoculum --- p.68 / Chapter 3.2.1.2 --- Culture --- p.68 / Chapter 3.2.1.3 --- Protein Precipitation --- p.68 / Chapter 3.2.1.4 --- Gel Filtration Column Chromatography --- p.69 / Chapter 3.2.1.5 --- Enzyme Assay --- p.69 / Chapter 3.2.1.6 --- Lipase Activity Confirmation --- p.70 / Chapter 3.2.1.7 --- Protein Determination --- p.70 / Chapter 3.2.2 --- Model Studies of the Formation of Free Fatty Acids and Ethyl Esters --- p.70 / Chapter 3.2.2.1 --- "A System with Lipid, Alcohol, and Lipase" --- p.70 / Chapter 3.2.2.2 --- A System with Different Lipase Concentrations --- p.71 / Chapter 3.2.2.3 --- A System with an Exogenous Fatty Acid --- p.71 / Chapter 3.2.3 --- Characterization of the Crude Lipase from Mucor hiemalis Culture on the Formation of Free Fatty Acids and their Ethyl Esters --- p.72 / Chapter 3.2.3.1 --- Effect of a Phospholipid --- p.72 / Chapter 3.2.3.2 --- Effect of Ethanol Concentration --- p.72 / Chapter 3.2.3.3 --- Effect of Sodium Chloride Concentration --- p.72 / Chapter 3.2.3.4 --- Effect of initial pH --- p.73 / Chapter 3.2.4 --- Orthogonal Design Experiment L9 (33) --- p.73 / Chapter 3.2.5 --- Free Fatty Acids Identification and Quantification --- p.76 / Chapter 3.2.5.1 --- Extraction --- p.76 / Chapter 3.2.5.2 --- Gas Chromatography-Mass Spectrometry Analysis (GC-MS) --- p.76 / Chapter 3.2.5.3 --- Compounds Identification and Quantification --- p.77 / Chapter 3.2.6 --- Ethyl Esters Identification and Quantification --- p.77 / Chapter 3.2.6.1 --- Extraction --- p.77 / Chapter 3.2.6.2 --- Gas Chromatography-Mass Spectrometry Analysis (GC-MS) --- p.78 / Chapter 3.2.6.3 --- Compounds Identification and Quantification --- p.78 / Chapter 3.2.7 --- Statistical Analysis --- p.79 / Chapter 3.3 --- Results and Discussions --- p.80 / Chapter 3.3.1 --- Lipase Partial Purification --- p.80 / Chapter 3.3.2 --- Lipase Activity Confirmation --- p.80 / Chapter 3.3.3 --- Model Studies on the Formation of Free Fatty Acids and Ethyl Esters --- p.84 / Chapter 3.3.3.1 --- "A System with Lipid, Alcohol and Lipase" --- p.84 / Chapter 3.3.3.2 --- A System with Different Lipase Concentrations --- p.84 / Chapter 3.3.3.3 --- A System with an Exogenous Fatty Acid --- p.89 / Chapter 3.3.3.4 --- Summary --- p.92 / Chapter 3.3.4 --- Characterization of the Crude Lipase from Mucor hiemalis Culture on the Formation of Free Fatty Acids and their Ethyl Esters Formation --- p.92 / Chapter 3.3.4.1 --- Effect of a Phospholipid --- p.92 / Chapter 3.3.4.2 --- Effect of Ethanol Concentration --- p.96 / Chapter 3.3.4.3 --- Effect of Sodium Chloride Concentration --- p.103 / Chapter 3.3.4.4 --- Effect of initial pH --- p.109 / Chapter 3.3.5 --- Orthogonal Design Experiment L9 (33) Optimizing the Ethyl Esters Formation --- p.114 / Chapter 3.4 --- Conclusion --- p.118 / Chapter 4 Overall Conclusions --- p.120 / References --- p.124

Soy flour was inoculated with Lactobacillus delbrueckii ssp. lattis R0187, and incubated for 8 h, to evaluate the protein hydrolysis and identify peptides generated by this fermentation, and the impact on ACE and trypsin inhibitory activities. Aqueous protein extracts prepared from different fermentation time periods showed a decrease in soluble protein content (from 2.83 to 0.02 mg/mL), while soluble inorganic nitrogen and free amino acid contents increased (from 0.029 to 0.062% w/w, and from 0.75 to 0.90% w/w, respectively). The protein extracts were analyzed by SDS-PAGE; proteolysis was observed after 5 h incubation of inoculated soy flour, suggesting that glycinin, beta-conglycinin, and trypsin inhibitors, were hydrolyzed. Peptides were isolated by tricine-SDS-PAGE, and analyzed by MS/MS; fragments of soy anti-nutritional factors (Kunitz and Bowman-Birk trypsir, inhibitors), as well as of other soybean proteins, were identified, confirming that these proteins were hydrolyzed. The protein extracts at time 0 h and 8 h were analyzed by RP-HPLC; one fraction was analyzed by MS/MS, which identified peptides from Lactobacillus species. Determination of trypsin inhibitory activity showed less inhibition of the enzyme with inoculated soy flour compared to the control (un-inoculated soy flour), confirming the deactivation of trypsin inhibitors by fermentation. Determination of ACE inhibitory activity showed a higher inhibition with the control (86% +/- 3.0) compared to inoculated soy flour (66% +/- 7.6).

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