Physico-chemical chlorophyll-a species in aqueous alcohol solutions determine the rate of its discoloration under UV light

Yasuda, Midori; Oda, Keisuke; Ueda, Toshihisa; Tabata, Masaaki

doi:10.1016/j.foodchem.2018.11.005

Cited by 21 publications

(12 citation statements)

References 28 publications

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“…The CD spectra of Chl (Figure 6) exhibited weak negative peaks at 660 nm, and in the cases of SE and QS, weak positive peaks were also observed at 715 nm. However, these CD intensities were significantly lower than that observed in the 60%−70% methanol and 50% ethanol solutions, where J‐aggregates of Chl‐a formed, as previously reported (Yasuda et al., 2019). The presence of both positive and negative peaks suggests regular interactions between Chl molecules (Engelmann et al., 2001; Oba et al., 1996).…”

Section: Resultssupporting

confidence: 82%

“…The UV–Vis spectra of Chl in the emulsifier solutions are shown in Figure 4. The red lines represent the spectra obtained in ethanol solution, where a peak is observed at 660 nm corresponding to the monomer of Chl (Yasuda et al., 2019). However, the spectra of Chl in the emulsifier solutions broadened and shifted to longer wavelengths.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 5 shows the fluorescence spectra of the Chl solution, where the red line represents the spectrum of Chl in ethanol. The large peak at 670 nm in this solvent represents the Chl monomer (Yasuda et al., 2019), and interestingly, in the emulsifier solutions, the intensity of this peak was low in each case, thereby implying that Chl aggregates were formed (Shi et al., 2013). In contrast, in the TX solution, the fluorescence intensity at 674 nm increased with increasing surfactant concentration, indicating that Chl changed from the aggregated form to the monomeric form as the concentration increased in the TX micelles.…”

Section: Resultsmentioning

confidence: 99%

“…The dissolved state of Chl was previously investigated in water–methanol and water–ethanol systems, and the effects of such compositions on the discoloration of Chl were examined (Yasuda et al., 2019). It was found that Chl formed self‐aggregates in the presence of these alcohols, thereby suppressing discoloration by light in aqueous solutions of both methanol and ethanol at alcohol concentrations as low as 10%.…”

Section: Introductionmentioning

confidence: 99%

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Effect of emulsifiers on the discoloration of chlorophyll and their potential for use in green beverages

Yasuda

Tabata

2021

Journal of Food Science

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The discoloration of chlorophyll (Chl) by light is an ongoing issue for green beverages in the food industry. To suppress the discoloration of Chl in aqueous solution, the effects of different emulsifiers were investigated on the discoloration of Chl under ultraviolet (UV) irradiation to determine their potential application for use as food additives. Sucrose fatty acid ester (SE), sorbitan fatty acid ester (TW), and quillaja saponin (QS) were used as emulsifiers, while Triton X‐100 (TX) was used for reference. The discoloration of Chl was measured using a color difference meter. The species of Chl in solution were determined using ultraviolet–visible (UV–Vis), fluorescence, and circular dichroism (CD) spectroscopy, and the particle size of Chl in solution was determined using dynamic light scattering. The Chl aggregates were observed by the observation of increased peak areas at longer wavelengths in the UV spectra of Chl, in addition to a reduced fluorescence intensity. The CD spectra showed that the Chl aggregates were arranged in a random structure. Furthermore, the average particle size of the Chl aggregates was determined to be approximately 100 nm. SE and QS were found to significantly enhance the formation of self‐aggregates due to their high hydrophilicities compared to those of TW and TX. As a result, SE and QS protect themselves from light to suppress the discoloration of Chl. The present results therefore suggest that SE and QS are suitable emulsifiers to address the problem of Chl discoloration in beverages, such as green tea and vegetable juices. Practical Application Chlorophyll (Chl), a green pigment present in vegetables and green tea, is discolored by light. In this study, it was found that emulsifiers (sucrose fatty acid ester and quillaja saponin) suppress the discoloration of Chl. The implementation of these emulsifiers as food additives would enable green tea or green vegetable juices to maintain their colors for long periods and could contribute significantly to the beverage industry.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of emulsifiers on the discoloration of chlorophyll and their potential for use in green beverages

Yasuda

Tabata

2021

Journal of Food Science

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“…Traditionally, aqueous ethanol is utilized for the recovery of polyphenol‐rich food grade extracts from plant materials (Huma, Jayasena, Nasar‐Abbas, Imran, & Khan, ). However, the use of ethanol results in the co‐extraction of high chlorophyll concentrations (Yasuda, Oda, Ueda, & Tabata, ). There are numerous examples of chlorophyll‐containing plant extracts being applied in dairy formulations and salad dressings either as functional ingredients or to increase their antioxidant stability (Abdalla & Roozen, ; O'Sullivan et al, ).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the impact of chlorophyll removal techniques on polyphenols in rosemary and thyme by‐products

2020

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The impact of dechlorophyllization (n‐hexane: water partitioning, activated charcoal bleaching, and ChloroFiltr® decolorization) on major polyphenols of two herbal by‐products (rosemary and thyme) was assessed. The aim was to produce decolorized extracts for food preservation and improve the quantification of their main phenolics. Activated charcoal bleaching and ChloroFiltr® decolorization effectively removed the chlorophyll a and b, whereas traces were detected after n‐hexane: water partitioning. Dechlorophyllized thyme extracts prepared using activated charcoal and ChloroFiltr® had the lowest relative antioxidant capacity index (RACI) values based on 2,2‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP), and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) antioxidant assays. Conversely, rosemary extracts had positive RACI values following treatment with activated charcoal, whereas n‐hexane led to a significant antioxidant loss. Chromatography‐mass spectrometry analyses indicated that phenolic diterpenes (carnosol and carnosic acid), as well as rosmarinic acid were in general not significantly decreased (p ˃ .05) after activated charcoal treatment, while n‐hexane maintained the flavonoids and phenolic acids with nonsignificant losses. Practical applications Commercial exploitation of polyphenol‐rich plant based extracts as natural antioxidant agents is impeded by their high chlorophyll content, which when incorporated in food products can result in products that do not meet the consumer expectations for appearance. This study has shown that the activated charcoal bleaching has potentials to remove chlorophyll and retain antioxidant polyphenols in particular diterpenes in fresh herb by‐products. Moreover, the commonly used n‐hexane was less effective in removing chlorophyll but retained the major flavonoids and phenolic acids. Thus, the choice of chlorophyll removal methods depend on retaining the class of antioxidant polyphenols abundant in the plant matrix.

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UV‐A treatment of phenolic extracts impacts colour, bioactive compounds and antioxidant activity

Ebrahimi,

Hoxha,

Mihaylova

et al. 2024

J Sci Food Agric

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BACKGROUNDThe unintended co‐extraction of chlorophylls during the recovery of polyphenols from plant sources yields green‐coloured phenolic extracts with limited use in colour‐sensitive foods. This study aimed at decolourizing the ethanolic extracts of sugar beet leaves using a UV‐A treatment (390 nm).RESULTSExposure of the phenolic extracts to 30 UV‐A LEDs at 8.64 J m−2 radiation dose decreased the total chlorophyll content by 69.23% and reduced the greenness parameter (−a*) significantly (P < 0.05) from 27.33 ± 0.32 to 8.64 ± 0.16. Additionally, UV‐A treatment increased the content of most individual phenolic compounds (e.g. gallic acid, ferulic acid, etc.) significantly, resulting in an increase in the overall phenolic content in the extracts from 900.56 ± 14.11 μg g−1 fresh weight (FW) to a maximum of 975.09 ± 9.62 μg g−1 FW at 0.67 J m−2. However, rutin content had a significant decrease at the highest radiation dose (8.64 J m−2). The soluble sugar content (i.e. glucose and fructose) increased simultaneously with phenolic compounds after the UV‐A treatment. Although the UV treatment reduced the 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity, it had no significant effect on the ferrous chelating activity and the extract's ability to delay lipid oxidation in corn oil. The antioxidant activity index of the treated extract was comparable to that of butylated hydroxytoluene, a synthetic antioxidant.CONCLUSIONKey findings of this study include successful decolourization of the extract, decomposition of bound polyphenols to their free form, and maintaining the antioxidant activity of the extract in the oil system after UV‐A exposure. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Physico-chemical chlorophyll-a species in aqueous alcohol solutions determine the rate of its discoloration under UV light

Cited by 21 publications

References 28 publications

Effect of emulsifiers on the discoloration of chlorophyll and their potential for use in green beverages

Effect of emulsifiers on the discoloration of chlorophyll and their potential for use in green beverages

Evaluation of the impact of chlorophyll removal techniques on polyphenols in rosemary and thyme by‐products

UV‐A treatment of phenolic extracts impacts colour, bioactive compounds and antioxidant activity

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