Effect of intermittent fluidized bed drying and ultrasonic extraction on polysaccharide gum of Yanang (Tiliacora Triandra Diels) leaves | |
| Author | Warintorn Nawarat Na Ayudthaya |
| Call Number | AIT Thesis no.FB-12-02 |
| Subject(s) | Yanang--Drying Fluidization |
| Note | A thesis submitted in partial fulfillment of the requirements for the d egree of Master of Engineering in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. no.FB-12-02 |
| Abstract | The kinetics of yanang leaves were determined using fluidized bed dryer for the temperature range 45 - 75 ⁰ c at the air velocity of 3 m/s, as compared to hot air oven at 45 ⁰ c. The temperature of 55 ⁰ c was then selected to do intermittent drying with the tempering period of 10 minutes. The results illustrated that fluidized bed drying could reduce moisture content faster than hot air drying and all fluidized air temperatures affected the drying rate, wh ich increased with the increase in he ated temperature, also the application of intermittent drying could enhance the drying rate approximately by 26% at the early stage, where the moisture cont ent of material being dried still high. Moreover, it consumed less energy than continuous mode . Despite high initial moisture content, the drying characteristic of yanang leaves took place only in the falling rate regime. Two mathematical models were chosen to fit the experimental data such as Lewis’s model and Page’s model. As a result, the Lewis’s model gave better prediction than Page’s model, and adequately described the drying behavior of yanang leaves. The product qualities in term of color, rehydration ratio and chlorophyll retention were also influenced by fluidized temperatures and tempering period. Lightness (L*) of yanang leaves was decreased with increasing temperature, while greenness (a*) and yellowness (b*) of yanang leaves were increased with increasing temperature. The employment of tempering period could retain relatively identical co lor as fresh leaves but could not preserve chlorophyll content, as retained in fresh leaves. The highest rehydration ratio was observed when using fluidized temperature of 45 ⁰ c, whereas inferior rehydration ratio was found in fluidized bed drying with temp ering time, which no significant difference when using hot air drying. Antioxidant characteristics of yanang leaves extracts were evaluated from four different extracting solvents (water, methanol, acetone and hexane). Folin - ciocalteu assay was used to qua ntify total phenolic content, which expressed as mg/g gallic acid equivalents (GAE). DPPH scavenging assay was used to determine antioxidant capacity. The result presented that methanolic extract provided the highest value in both total phenolic content (3 .19 mg/g gallic acid) and antioxidant activity , which used only 95.50 ppm to inhibit biological process by half . Yanang gum was extracted from yanang leaves powder by ultrasonically assisted extraction. The effect of three different factors (water/mater ial ratio, extraction time and extraction power) was investigated. The optimum condition for gum extraction was found at the solvent/material ratio of 20:1 (mL/g) for 10 minutes at the extraction power of 120 W. Under this condition, the highest yield of p olysaccharide gum was attained, equal to 5.93%. Furthermore, using this ultrasonic treatment resulted in increasing the yield of polysaccharide gum markedly, as compared to traditional method , which yielded only 2.36%. The effect of yanang gum was further investigated on gelatinization behavior of wheat flour. It was observed that the addition of YG caused the reduction in peak, breakdown and set back viscosity, whereas that led to increase the pasting temperature. |
| Year | 2012 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. no.FB-12-02 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Athapol Noomhorm; |
| Examination Committee(s) | Rakshit, Sudip Kumar;Anal, Anil Kumar; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2012 |