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Содержание

Comparing the Biochemical Compositions of Fruits From the Sambucus Species and the Color Expression of Their Anthocyanin Extracts as Modulated by UV Irradiation- [electronic resource]

자료유형: 학위논문파일 국외

최종처리일시: 20240214101932

ISBN: 9798380181617

DDC: 641

저자명: Zhou, Yucheng.

서명/저자: Comparing the Biochemical Compositions of Fruits From the Sambucus Species and the Color Expression of Their Anthocyanin Extracts as Modulated by UV Irradiation - [electronic resource]

발행사항: [S.l.]: : The Ohio State University., 2021

발행사항: Ann Arbor : : ProQuest Dissertations & Theses,, 2021

형태사항: 1 online resource(197 p.)

주기사항: Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

주기사항: Advisor: Giusti, M. Monica.

학위논문주기: Thesis (Ph.D.)--The Ohio State University, 2021.

사용제한주기: This item must not be sold to any third party vendors.

초록/해제: 요약Sambucus (elderberry) is a woody perennial that produces fruits rich in anthocyanins. The two most economically important species around the world are the European elderberry (S. nigra L.) and the American elderberry (S. canadensis L.). The European elderberry has a long history of being grown as a commercial fruit crop therefore it is better known than other species. The American elderberry is native to the North America, but it has not been studied as much as its European counterpart. There are many other Sambucus species. Among them, S. peruviana is a species native to South America with limited information reported in the literature.The anthocyanin content in elderberry fruits is higher than that of most other berries and for that reason the European elderberry extract has been commercialized as a natural food colorant. The anthocyanin concentration and profile, along with other biochemical attributes are greatly impacted by genetic (like species, cultivar) and environmental (like ripeness) factors. These variations can affect the coloring properties of their anthocyanin extracts and will ultimately determine their application in food industry. Being S. canadensis being the North American native species and less studied than the European counterpart, our study focused greatly on this species, while its colorimetric properties were compared with other Sambucus species including S. nigra and S. peruviana to compare their application potential.In the first two chapters, we aimed to investigate the impact of cultivar and ripeness on the accumulation of anthocyanin and other phytochemicals in American elderberry, systematically evaluate the anthocyanin profiles and color properties of S. nigra, S. canadensis and S. peruviana under a wide pH range for their potential as natural food colorants.Biochemical compositions of American elderberry greatly changed during fruit ripening. °Brix increased ~4 unites, pH increased from 4.2 to 4.5, anthocyanin content multiplied about tenfold and phenolic content multiplied almost threefold from the half-to the fully-ripen stage, while the % acylated anthocyanins decreased from 80% to 70%. Different American elderberry cultivars significantly varied on pH, anthocyanin content and polymeric color. More than 70% anthocyanins in S. canadensis were acylated with p-coumaric acids, with trans (~65%) and cis-configured (~2%) cyanidin-3-p-coumaroylsambubioside-5-glucosides coexisted. S. canadensis was abundant in cyanidin-3,5- glycosides (90%), while S. nigra (80%) and S. peruviana (~100%) were dominated by the non-acylated cyanidin-3-glycosides. Nearly 30% of anthocyanins in S. peruviana were cyanidin-3-lathyroside, which were not commonly found in nature. The different anthocyanin glycosylation and acylation pattern resulted in a more orange-red color expression of the S. nigra and S. peruviana extracts at acidic pH, less color loss at pH 4- 6, and a blue color expression of the S. canadensis extract at alkaline pH. According to their different color properties, they can be good candidates for the replacement of red and blue dyes.American elderberry is one of the few edible plants that contains both cis and trans isomers, therefore can be used to investigate the impact of acyl group configuration on the anthocyanin color expression and stability.The cis-configured cyanidin-3-p-coumaroyl-sambubioside-5-glucosides isolated from American elderberry exhibited larger \uD835\uDF06vis-max with more intense (higher Amax and smaller L* ) and more saturated (larger C* ab) colors expressed at almost all pHs than its trans counterparts. It experienced less color loss at mildly acidic pH due to its spatial configuration. Half-lives of the cis isomers were 2-6 times longer than the trans depending on pH. These favorable attributes indicated that an extract rich in cis isomers would potentially express more vital colors with improved stability.The cis-configured anthocyanins are rarely found in nature, while they may be isomerized from the trans through UV irradiation. Current knowledge on anthocyanin photoisomerization is limited, leaving a gap to fill in. For this reason, we first identified the key factors that governed this conversion process and modelled the reactions under different irradiation conditions. We then developed a food-friendly and sustainable approach to produce more cis isomers efficiently. We further verified the feasibility of improving anthocyanin extracts color intensity and stability through UV irradiation. Photoisomerization of anthocyanin was more efficient with isolates but Photoisomerization of American elderberry crude extract resulted in the accumulation of cis isomers, and reached a photo-stationary phase in just 12 min. The anthocyanin photoisomerization was solvent and dose-dependent. Under all the tested conditions, the highest cis/trans ratio (~0.75) and the conversion efficiency (k = 0.54) was obtained when irradiating 100 \uD835\uDF07M American elderberry crude extract in 90% ethanol. The increased cis/trans ratio in the extract after UV irradiation significantly intensified the overall color expression with extended shelf life.Our investigation of biochemical compositions and color performance of multiple American elderberry cultivars at different ripening stages helped to guide the selection of appropriate materials for specific research and application purposes. Our systematic evaluation of colorimetric properties among different Sambucus species suggested that the application of Sambucus species as natural colorants could be extended to other less utilized species like S. canadensis and S. peruviana. Our study on cis and trans cyanidin stereoisomers provided important additions to the current knowledge on the relationship between acyl group configuration and anthocyanin color expression. Our exploration of anthocyanin photoisomerization suggested that UV irradiation could be a feasible approach to intensity anthocyanin color expression and improve the stability.