| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系所 === 97 === Micro/nano processing may effectively increase the extraction of functional ingredients from foods. Djulis (Chenopodium formosanum Koidz.), an aboriginal cereal plant in Taiwan, is abundant in functional ingredients and colorful pigment. However, the coarse texture limited its application in food industry. It might be a chance to use the micro/nano processing to broaden the utilization of Djulis after being ground into powder. No information related the effects of micro/nano processing on the pigment, functional ingredient and antioxidant capacity of Djulis can be found. The aim of this study is to investigate the functional ingredients (general nutrients, pigment and poly phenol) as well as color qualities and antioxidant capacities of Djulis after being ground into different particle sizes. Effects of temperature and package during storage were also studied. Finally, the identification of pattern of its pigment by LC-MS and effect of color qualities and antioxidant capacities at different pH were also investigated.
Result showed that the average diameter of nano particle obtained from milled Djulis were about 75 nm through the observation of TEM. Much more physicochemical ingredients, such as color qualities (Aλmax, Hunter a and chroma), reducing sugar, water soluble solid, protein, amino acid, trace minerals (calcium, iron, magnesium and zinc), betalain pigment and total phenol were found in the Djulis sample after micro/nano processed. It suggested that, more functional ingredient were extracted when the particle sized decreased. Moreover, the ferrous ions chelating ability (FICA), DPPH scavenging ability and FRAP reducing power were higher when the particle sizes were more shedder. It suggested that the extraction of functional ingredients might be enhanced due to the increase of surface area. On the contrary during storage, the pigment stability and antioxidant capacity decreased to result in Djulis when the large surface area by particle sized decreased. This is in accordance with the pigment activation energy (4.05、3.84 and 2.37 kcal/mol in IG, MP and NP, respectively). For the package study, vacuum package with low temperature (4℃) was found the best for stabilizing the pigment and antioxidant capacity of Djulis with nano particles.
For pigment identification and pH stability, the major source of red pigment was found to be betalains. HPLC purification and LC-MS identification indicated that the major betacyanin of red Djulis were betanin (m/z 551), isobetanin, armaranthin (m/z 727) and isoamaranthin. Furthermore, the pigment exhibited the best color quality and antioxidant capacity at pH 5 tested by a model system.
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