Improved Stability of Blue Colour of Anthocyanins from Lycium ruthenicum Murr. Based on Copigmentation
Round 1
Reviewer 1 Report
The article “Improved stability of blue colour of anthocyanins from Lycium ruthenicum Murr. based on copigmentation” shows o use of copgmentation to better the stability of blue color natural anthocyanins. The findings of this article show a new perspective on the use of anthocyanins as a blue dye and contribute to its large-scale application in the food industry since blue dyes in nature are rare and synthetic dyes are used in foods and can have adverse effects on human health. However, I have some observations:
1) Please increase the introduction section and add a more detailed paragraph about pigmentation.
2) Please suggest a perspective for using anthocyanins from Lycium ruthenicum Murr based on pigmentation and the side effects of synthetic dyes in the Results and Discussions section.
Author Response
Response to Reviewer 1 Comments
Point 1: Please increase the introduction section and add a more detailed paragraph about pigmentation.
Response 1: We gratefully appreciate your comment. We added a more detailed paragraph for the introduction.
Introduction, Line 72-82, Adding: “Copigments are collections of compounds such as flavonoids, alkaloids, amino acids, organic acids, nucleotides, polysaccharides, metals or other anthocyanins that have the function of improving the colour of anthocyanins and their stability [19]. Existing studies have shown that the addition of plant extracts as copigments can stabilise and enhance the colour of foods [20,21], and research suggested that multiple components of the juice substance work together in copigmentation, which enhances the colour appearance [22]. The occurrence of the copigment effect is usually accompanied by a red shift in λmax and simultaneous bluing of the colour, producing a colour-enhancing effect [23]. This bluish-colour effect is mainly caused by the quinone bases and is stabilised by the copigments [24]. Based on this theory, it is possible to obtain the blue colour anthocyanins by copigmentation.”
Point 2: Please suggest a perspective for using anthocyanins from Lycium ruthenicum Murr based on pigmentation and the side effects of synthetic dyes in the Results and Discussions section.
Response 2: We sincerely appreciate your precious comment. We added a more detailed paragraph in the Results and Discussions section.
Results and Discussions, Line 110-120, Adding: “Blue pigments are rare in nature and even rarer in edible form. Modern artificial blue pigments are linked to environmental and health hazards, such as attention deficit and hyperactivity disorders in children [30]. In the face of such risks, there is an increasing demand for natural colourants. Anthocyanins from LR, which are rich in petunidin derivatives, have received much attention and research for their unique violet-blue colour and wide colour ranges and have great potential as a natural blue colourant [16]. It has been shown that copigments can enhance the colour and stability of anthocyanins by protecting chromophores from hydration [31]. Moreover, copigments can increase the redshift of λmax and the absorbance of anthocyanins [23]. Therefore, we envisage a strategy to design blue anthocyanins based on the wide colour ranges of LR’s anthocyanins by screening for copigments.”
Reviewer 2 Report
Abstract
L14 Erase ‘anthocyanins’
L14 CIE and AFM are unfamiliar abbreviations. Explain them when first mentioned.
L15 Release ACNs from the parenthesis
L17 ‘close’ rather than ‘closed’
L19 Remove ‘significantly’
Language has to be strongly improved throughout the manuscript!!
Introduction
Mention also some of the common names of the plant species investigated, e.g. black fruit wolfberry, siyah goji, and kaoke.
CIE lab is extensively used in this work. Include a description of what is measured and how blue colours are related to the measurements. This has been done in short as explained in line 179-180 and in the supplementary figure A6.
Results and Discussion
L97 Figure A3-C: If the figure is actively discussed in the section, it should be included in the manuscript rather than in the supplementary section.
L101-102 Not clear
Fig 1 The font size of the concentrations should be enlarged.
L123 Explain the abbreviations at the first time
L125 Neutral? Are we talking about pH?
L147 Rather than using a sentence as reference, simply write (Table A1).
L273 I really don’t see the purpose of 1H-NMR, and the fact that there is an upfield shift in the proton resonances when increasing the ratio of PX to CAN, what does it tell? Remember that by increasing PX you also make changes of the solvent. The explanation is unclear.
L279 p3cr5g: Write out the first time this occur in the text (petunidin-3-O-coumaroylrutinoside-5- 383 O-glucoside)!
L292 This paragraph is unclear. As with H NMR the rationale of using this technique is not well described.
L308 Unclear
L322 Write out full name of IGM at the first time for this abbreviation.
L324 ‘are’ rather than ‘were’?
L385 ‘with purity＞95%’ How was this measured?
L393 ‘macroporous resins (AB-8)’ Supplier/producer?
L399 What solvent?
L427 ‘The left Riemann sum was used for calculating the integration of these areas.’ Include a reference.
L435 The experiments have been run at 40 ℃, whereas the literature references used 50 ℃ (L207). Why were the lower temperature chosen?
L448 Which UV–Vis spectrophotometer? Manufacturer?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Round 2
Reviewer 2 Report
The revised manuscript includes changes in accordance to the previous review.
