Profiling Analysis of Isomalto-Oligosaccharides Using LC-MS/MS
Isomaltooligosaccharides are indigestible carbohydrates with prebiotic properties. Analytical platforms are important for the food industry to monitor the characteristics and to study the properties of isomaltooligosaccharides. However, the profile of isomaltooligosaccharides is complex with a versatile polymerization number of sugar units and linkage types, which presents a challenge, especially identification of isomers. The objective of this study is to use liquid chromatography-tandem mass spectrometry (LC-MS/MS) to establish an analytical platform for determining the profiles of complex isomaltooligosaccharides. Graphitized carbon liquid chromatography (GCC) of LC was used to resolve complex isomers. The developed platform can identify the isomers from degree of polymerization (DP) 2 to 12 by the elucidation of the characteristic fragment ions. Dimers, trimers, and tetramers are major components of selected commercial isomaltooligosaccharides products. Six dimers, 13 trimers, and 10 tetramers were identified. α-1→6 and 1→4 were the major linkages, whereas isomers with α-1→2, 1→3, and even 1?1 linkages were also identified. The DP proportions of 3 commercial isomaltooligosaccharides products were similar while isomer profiles of dimers, trimers, and tetramers were significantly different. The major proportion differences contributed from 62 glucosyl maltose, 63 glucosyl maltotriose, isomaltotetraose. The established analytical platform can be a useful tool for studying the structures and the prebiotic-efficacy relationship of isomaltooligosaccharides products.
O.54 AUTHENTICATION OF TAIWAN QUINOA (CHENOPODIUM FORMOSANUM, DJULIS) BY PHYTOCHEMICAL FINGERPRINT USING HIGH-RESOLUTION MASS SPECTROMETRY
Djulis (Chenopodium formosanum) is a traditional cereal as food source used by Taiwan aboriginal people. Djulis belong to Amaranthaceae family, similar to the quinoa (C. quinoa) and amaranth (Amaranthus hypochondriacus), Because of its high nutritional values, Djulis is gradually gaining popularity in recent years. However, the research in djulis is very limited. The aim of this foodomics study is to establish a phytochemical fingerprint analysis to discriminate those Amaranthaceae plants using UHPLC-DAD-ESI-Orbitrap. In the target component analysis, eight betalanins, 69 phenolic compounds and 69 triterpenoid saponins were identified according to the accuracy mass, fragments of MS2, isotope pattern and UV-VIS spectrum. Djulis is rich in betalains including amaranthin, isoamaranthin, betanin, isobetanin, celosianin II, isocelosianin II, lampranthin II, and isolampranthin II. For phenolic compounds, Djulis has more diversity of flavonoids compared to quinoa (major in quercetin and kaempferol). In triterpenoid saponins, 3-O-hexoside-oleanolic acid 28-O-β-D-hexoside and 3-O-hexoside-hexoside-oleanolic acid 28-O-β-D-hexoside are the characteristic OA type of saponins in Djulis. However, quinoa has more PA or HED type of saponins. In non-target component analysis, the results of principal component analysis showed that the first principal component could distinguish amaranth from the other two plants, and the second principal component could distinguish djulis and quinoa. Rutin is the main characteristic metabolite in Djulis; and quercetin pentose glucuronide and mauritianin are the main compounds in quinoa. Our study established a phytochemical compound profile for authentication of Djulis. The comprehensive analysis may useful on quality control to preventing adulteration.
Gui-ru XIE, Hong-jhang CHEN (陳宏彰)
P-1 5 EFFECTS OF SOAKING WITH PULLULANASE TREATMENT ON PROPERTIES AND DIGESTIBILITY OF COOKED RICES
Cooked rice is readily hydrolyzed by amylases after ingesting, resulting in a high glycemic index. Slowly digestible starch (SDS) and resistant starch (RS) offer a slow increase of postprandial blood glucose level and many other health benefits. Pullulanase can selectively cleave 1,6-α-D-glycosidic bonds at branching points, leading to the generation of linear short amylose with low molecular weight. Debranched starch is a good source of SDS and RS. Most literature focuses on debranching of isolated starch. The purpose of the study was to investigate the effects of soaking rice kernels with pullulanase on properties and digestibility of cooked rices. Waxy rice (WR) and low-amylose rice (LAR) were soaked at 65 oC for 2 h with different levels of pullulanase (0-900 NPU/100 mL). The results showed that the optimum pullulanase concentrations for WR and LAR were 700 and 300 NPU/100 mL. As the pullulanase increased, the solid content leached from soaked rice increased significantly. Soaking at the higher pullulanase concentration decreased integrity of raw rice grains, and cooked LAR had more breakage than cooked WR. Furthermore, the SDS and RS of cooked rice at the optimum pullulanase concentration were 17.2% and 5.31% for WR; and 21.66% and 4.73% for LAR. The pullulanase treatment slightly decreased estimated glycemic index (eGI) of WR from 100.79 to 95.08 and LAR from 90.03 to 87.57. Except the lower appearance score due to some broken rice, the sensory evaluation indicated soaking with pullulanase treatment improved aroma for both WR and LAR, but increased hardness and deceased stickiness for WR.