Characteristics And Anthocyanins Process Stability Of Purple Sweet Potatoes Used For Fresh Cooking Or Manufacturing

With the improvement of living standards and human medicine, healthy natural pigments have been used wildly by the whole world, which were gradually replacing the coal synthetic aniline pigments, in order to improve the reliability of consumer safety. Global natural pigments markets were rapid growth at twice speed than synthetic pigments. Purple sweet potato anthocyanins were kinds of natural pigments with many physiological health functions like anti-oxidation, anti-mutagenic, anti-aging, anti-inflammatory and so on. Purple sweet potato anthocyanins were kinds of natural anthocyanins pigments resources which were used as functional additives and health function factor in food industry. This paper researched on the relationship of the main ingredient of fresh cooking/manufacturing purple sweet potatoes from different sources. Optimized measurement conditions of p H differential method. Investigate the influence of total anthocyanins contents, taste, aglycone, monomer anthocyanins and DPPH with five Chinese cooking processing methods. Discuss the interaction relationship of anthocyanins and gliadins. The main results are as follows:1. It was used CIELab, HPLC-PDA-ESI-MSn methods to establish the difference of color, main ingredient and the structure of anthocyanins in purple sweet potatoes from different sources. It shown that:The numerical of L*, a*, b*of fresh cooking purple sweet potatoes were higher than manufacturing purple sweet potatoes, while the numerical of c* and h had little difference. The numerical of △E* were closer between each fresh cooking purple sweet potatoes, but have much difference with manufacturing purple sweet potatoes. It proved that the color of fresh cooking purple sweet potatoes were much brighter.The contents of water, protein, starch, insoluble dietary fiber and anthocyanins of each fresh cooking/manufacturing purple sweet potatoes and relationship with CIELab have been measured. The results shown that the contents of water, protein, starch and anthocyanins have significant difference(P<0.05) between each fresh cooking/manufacturing purple sweet potatoes, while the contents of insoluble dietary fiber have not. The contents of anthocyanins expressed very significant positive correlation with the color of fresh cooking/manufacturing purple sweet potatoes.Finally identified the structure of anthocyanins of each fresh cooking/manufacturing purple sweet potatoes by HPLC-PDA-ESI-MSn. The results shown that the main anthocyanins of each purple sweet potatoes were cyanidins and peonidins, and fresh cooking purple sweet potatoes have much more non-acyl/ acyl anthocyanins than /manufacturing purple sweet potatoes.2. Optimized measurement conditions of p H differential method. It used λmax and 700 nm, p H1.0 and p H5.5 buffer, 40℃ and 100 min as measurement conditions, peonidin-3-(6’caffeoyl-6’’feruloylsophoroside)-5-glucoside replaced cyanidins-3-glucoside as standard. This optimized method has better stability, precision, repeatability and reproducibility, which RSD% were 2.1195%, 0.5474%, 0.7533% and 2.0967% respectively. This method can be used in measured purple sweet potatoes, and provided a new way to quantitative.3. The loss rate of fresh cooking/manufacturing purple sweet potato under five Chinese cooking methods were microwave < steam < boil< hypothermia deep-fry<bake. The taste of purple sweet potatoes has expressed negative correlation with anthocyanins contents after cooking. During cooking, the aglycone maintain stable, the loss rate of monomer anthocyanins were sig-acylated higher than dou-acylated anthocyanins. The DPPH ability were hypothermia deep-fry>microwave > steam > boil >bake.4. It was first time to study the interaction between purple sweet potatoes and gliadins by UV spectroscopy and fluorescence spectroscopy. The results suggested that purple sweet potatoes anthocyanins had a strong ability to quench the gliadins fluorescence in a static mode with hydrogen bonds and van der waals forces. The synchronous fluorescence spectra revealed that purple sweet potatoes anthocyanins can lead to structural changes and interacted with tryptophan residues in gliadin.