TRƯỜNG ĐH SƯ PHẠM KỸ THUẬT TPHCM KHOA CN Hóa Học & Thực Phẩm BỘ MÔN CN Thực Phẩm ĐÁP ÁN ĐỀ THI CUỐI KỲ HỌC KỲ II NĂM HỌC 2015 - 2016 Môn: Anh văn chuyên ngành – Thực Phẩm Mã môn học: FENG223950 ĐỀ 01 Passage 01 (4/10) What are proteins? (0.2) Proteins are polymers of amino acid are formed through amide linkages How many structures proteins have? What are they? (0.2) Proteins have four structure, including primary, secondary, tertiary and quaternary structures What can be considered as causes of protein denaturation? (0.2) Treatments that cleave hydrogen bridges, ionic or hydrophobic bonds are considered to cause protein denaturation Which chemical linkages are formed in irreversible denaturation? (0.2) Disulfide bonds Which factors that influence the solubility of proteins? (0.2) Factors that influence the solubility of proteins are the number of polar and a-polar groups and their arrangement along the molecule Which kinds of food products that rely on foam forming property of proteins? (0.2) Baked goods, sweets, desserts and beer How proteins stabilize the foam? (0.2) By forming flexible, cohesive films around the gas bubbles and therefore reduce the surface tension, proteins stabilize the foam How many phases are required to form protein gel? (0.2) 02 phases What are the properties of polymeric network gel? (0.2) Low polymer concentration (∼1%), transparency and fine texture, gel formation is caused by setting a certain pH, by adding certain ions, or by heating/cooling, thermo-reversible 10 What is “thermo-reversible”? (0.2) Thermo-reversible is the ability to reverse to its original structure when the temperature changes 11 Yes; 12 No; 13 Yes; 14 Yes; 15 Yes; 16 No; 17 No; 18 No; 19 No; 20 Yes Passage 02 (3/10) Short description of Tara-gum (maximum 70 words) Tara Gum is a Galactomannan, natural thickener, emulsifier and stabilizer obtained from the milling of the endosperm of the seeds of Tara tree Tara gum has synergistic effects when used in combination with kappa-carrageenan, Xanthan gum and agar, comparable to LBG Tara gum increases gel strength and makes the gel less prone to syneresis or produces long-term suspensions when combined with Agar and Carrageenan, and Xanthan gum, respectively Comparison of Tara-gum with other additives Characteristics Tara-gum Constituents identification Mannose:galactose is 3:1 Mannose:galactose is 3:1 Color powder identification White to cream, odorless White to brown, characteristic odor Color solution identification Translucent, soluble up to 55 Brix White to yellow, soluble just 35 Brix Gel test - Producing strong gel in combination with Carrageenan - Not producing strong gel - Forming well with Xanthan Gum Guar-gum - Not forming gel with Xanthan gum Stability in Very high frozen and defrozen products Low Mounthfell a full bodied slimy Granulometry test 100 mesh 200 mesh Aerobics plate count Up to 800 cfu/g Upt to 10.000 cfu/g Gummy texture Gummy Without gummy Passage 03 (3/10) In this study, three probiotic species including Lactobacillus acidophilus, Bacillus clausii and Saccharomyces boulardii were coated by “hydrogel” encapsulation technique with sodium alginate (single layer) or combination of sodium alginate and gelatin (double layer) The free and encapsulated probiotic cells were subsequently inoculated in gastrointestinal media for 120 to examine the protective benefits of the layers The results indicated that free L acidophilus and B clausii were completely inactivated after 60 and 90 incubated at low pH condition respectively Single-layer encapsulation lengthened survival of both bacterial species by 30 while those encapsulated by double layers were unaffected (in term of viable cell density) Free yeast showed better acid tolerance than bacteria with more than 10^3 viable cells after 120 prolonged under pH 2.0 The viable cell density of yeast encapsulated by single layer decreased gradually during the inoculation but with a lower death rate compared to that of the free yeast Double-layer encapsulation, however, significantly improved survivability of the yeast and no reduction in viable cell density of the yeast was observed for 120 Tolerance of the three species under intestinal condition followed the similar pattern to that under gastric condition SEM pictures of alginate-microbeads encapsulated probiotics demonstrated that the improvement in intolerance of probiotics to gastro-intestinal conditions was due to the protection of encapsulating molecules against external inhibition ... Constituents identification Mannose:galactose is 3:1 Mannose:galactose is 3:1 Color powder identification White to cream, odorless White to brown, characteristic odor Color solution identification Translucent,... combination with Carrageenan - Not producing strong gel - Forming well with Xanthan Gum Guar-gum - Not forming gel with Xanthan gum Stability in Very high frozen and defrozen products Low Mounthfell... Tara gum increases gel strength and makes the gel less prone to syneresis or produces long-term suspensions when combined with Agar and Carrageenan, and Xanthan gum, respectively Comparison of