Dorris Matthew R, Bolling Bradley W
Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
Department of Food Science, University of Wisconsin-Madison, Madison, WI 53706, USA.
Antioxidants (Basel). 2021 Nov 9;10(11):1788. doi: 10.3390/antiox10111788.
Anthocyanins degrade in fruit juice during storage, reducing juice color quality and depleting the health-promoting components of juice. Common water-soluble products of anthocyanins' chemical degradation are known, but little is known about the contribution of the insoluble phase to loss processes. Cranberry juice and isolated anthocyanins were incubated at 50 °C for up to 10 days to determine polyphenol profiles and degradation rates. Anthocyanin-proanthocyanidin heteropolymers were analyzed via Matrix Assisted Laser Desorption/Ionization (MALDI)- Time of Flight (TOF) Mass Spectrometry (MS). Formation of soluble protocatechuic acid accounted for 260 ± 10% and insoluble materials for 80 ± 20% of lost soluble cyanidin-glycosides in juice, over-representations plausibly due to quercetin and (epi)catechin in cranberry juice and not observed in the values of 70 ± 20% and 16 ± 6% in the purified anthocyanin system. Loss processes of soluble peonidin-glycosides were better accounted for, where 31 ± 2% were attributable to soluble vanillic acid formation and 3 ± 1% to insoluble materials in cranberry juice and 35 ± 5% to vanillic acid formation and 1.6 ± 0.8% to insoluble materials in the purified anthocyanin system. Free anthocyanins were below quantifiable levels in precipitate, implying most anthocyanins in precipitate were polymeric colors (PCs). PCs in the precipitate included cyanidin- and peonidin-hexosides and -pentosides covalently bonded to procyanidins. Therefore, formation of cranberry juice precipitate does not deplete a large portion of soluble anthocyanins; rather, the precipitate's pigmentation results from PCs that are also present in the soluble phase.
花色苷在果汁储存过程中会降解，降低果汁的色泽品质，并消耗果汁中具有促进健康作用的成分。花色苷化学降解的常见水溶性产物是已知的，但对于不溶性相在损失过程中的作用却知之甚少。将蔓越莓汁和分离出的花色苷在50℃下孵育长达10天，以确定多酚谱和降解率。通过基质辅助激光解吸/电离（MALDI）-飞行时间（TOF）质谱（MS）分析花色苷-原花青素杂聚物。在果汁中，可溶性原儿茶酸的形成占可溶性矢车菊素-糖苷损失的260±10%，不溶性物质占80±20%，这种过高的占比可能是由于蔓越莓汁中的槲皮素和（表）儿茶素导致的，而在纯化的花色苷系统中，这两个数值分别为70±20%和16±6%，未观察到这种过高占比的情况。可溶性芍药色素-糖苷的损失过程得到了更好的解释，在蔓越莓汁中，31±2%归因于可溶性香草酸的形成，3±1%归因于不溶性物质；在纯化的花色苷系统中，35±5%归因于香草酸的形成，1.6±0.8%归因于不溶性物质。沉淀中游离花色苷低于可定量水平，这意味着沉淀中的大多数花色苷是聚合色素（PCs）。沉淀中的PCs包括与原花青素共价结合的矢车菊素和芍药色素的己糖苷和戊糖苷。因此，蔓越莓汁沉淀的形成并不会消耗大部分可溶性花色苷；相反，沉淀的色素沉着是由也存在于可溶相中的PCs导致的。
