Stability of Chlorophyll as Natural Colorant: A Review for Suji (Dracaena angustifolia (Medik.) Roxb.) Leaves’ Case

Stabilized chlorophyll-based food colorants from spinach: Kinetics of a tailored enzymatic extraction

An organic solvent-free method based on limited dosing options (biocatalyst and zinc chloride) for the quick and mild recovery of chlorophyll (Chl) from spinach has been proposed. This tailored, custom-made protocol has been designed to produce stable green natural colorants. The kinetics of pigment extraction turned out to be a very useful tool to identify the proper conditions, in terms of biocatalyst dose (0.10-50 U/g), extraction time (1-48h), and ZnCl2 amount (50-300ppm), both for enhancing the recovery yield and preserving the green color. Considering the extraction kinetics, the recovery yield, and the colorimetric data, the suitable conditions to produce stable green and food-grade colorants are 0.10 U/g of enzyme, 3h, and 150ppm of ZnCl2 at 25°C. The extraction yield of Chl (4863µg/U) was about 51% greater than control, with a higher extraction rate constant (5.43 × 10-4 g/(µg min)). Considering the impact of ZnCl2 amount on Chl, its protective action resulted to be more noticeable toward Chl a: at 150ppm, an increased amount of about 2.5 and 1.5 times was found for Chl a and Chl b, respectively, in comparison to the reference (0ppm ZnCl2). PRACTICAL APPLICATION: This research demonstrates how a suitable kinetic approach helps to provide a tailored protocol, customized for the vegetable matrix, to produce stable green natural colorants from spinach. Lowering enzyme dosage and ZnCl2 amount during the extraction of chlorophyll at low temperature is crucial for its potential use as a colorant in food industry, providing high economic values through saving time and environmental protection.

Infesting Seaweeds as a Novel Functional Food: Analysis of Nutrients, Antioxidants and ACE Inhibitory Effects

Globalization and climate change are both contributing to an increase in the number of potentially invasive algae in coastal areas. In terms of biodiversity and financial losses, the invasiveness of algae has become a significant issue in Orbetello Lagoon. Indeed, studies from the Tuscany Regional Agency for Environmental Protection show that the reduction in dissolved oxygen caused by algal diffusion is detrimental to fisheries and biodiversity. Considering that wakame and numerous other potentially invasive seaweeds are consumed as food in Asia, we assess the nutritional and nutraceutical qualities of two potentially invasive seaweeds: Valonia aegagrophila and Chaetomorpha linum. We found that both algae are a valuable source of proteins and essential amino acids. Even if the fat content accounts for less than 2% of the dried weight, its quality is high, due to the presence of unsaturated fatty acids. Both algae are rich in antioxidants pigments and polyphenols, which can be exploited as nutraceuticals. Most importantly, human gastrointestinal digestion increased the quantity of polyphenols and originated secondary metabolites with ACE inhibitory activity. Taken together, our data strongly promote the use of Valonia aegagrophila and Chaetomorpha linum as functional foods, with possible application in the treatment of hypertension and cardiovascular diseases.

Indication of the color change on the oxidation properties of fragrant rapeseed oil during shelf storage

The cause and trend of color change and their links to oxidative properties were investigated by simulating shelf storage conditions for fragrant rapeseed oils (FROs). Under illumination, the L* value gradually increased with the storage time. The a* and b* values showed different trends depending on brands. The photodegradation rates of chlorophylls were 8.6 ∼ 15 times higher than those of carotenoids. The change in color of FROs was mainly caused by the light-induced photodegradation of chlorophyll. Compared with the hydroperoxides, the contents of some secondary oxidation products [i.e., 2-butenal, octane, (Z)-2-octene, 2,4-octadiene, (Z)-2-heptenal, (E, E)-2,4-heptadienal, and (E)-2-decenal] were more closely associated with the color variation with correlation coefficients of 0.6 ∼ 0.94. Significant negative correlation was found between α-tocopherol content and oil color difference. Therefore, illumination was the main reason for the color degradation of the FROs. The varying degree of color difference was strongly linked to the quality deterioration caused by oxidation.

Biocolorants in food: Sources, extraction, applications and future prospects

Color of a food is one of the major factors influencing its acceptance by consumers. At presently synthetic dyes are the most commonly used food colorant in food industry by providing more esthetically appearance and as a means to quality control. However, the growing concern about health and environmental due to associated toxicity with synthetic food colorants has accelerated the global efforts to replace them with safer and healthy food colorants obtained from natural resources (plants, microorganisms, and animals). Further, many of these biocolorants not only provide myriad of colors to the food but also exert biological properties, thus they can be used as nutraceuticals in foods and beverages. In order to understand the importance of nature-derived pigments as food colorants, this review provides a thorough discussion on the natural origin of food colorants. Following this, different extraction methods for isolating biocolorants from plants and microbes were also discussed. Many of these biocolorants not only provide color, but also have many health promoting properties, for this reason their physicochemical and biological properties were also reviewed. Finally, current trends on the use of biocolorants in foods, and the challenges faced by the biocolorants in their effective utilization by food industry and possible solutions to these challenges were discussed.

Effects of thermal treatments on the characterisation of microencapsulated chlorophyll extract of Caulerpa racemosa

Caulerpa racemosa is a macroalga that has a green pigment, that is, chlorophyll. Chlorophyll is highly sensitive to damage during heat processing. In the present work, C. racemosa chlorophyll extract was microencapsulated with fish gelatine and Arabic gum coatings, using a freeze-drying technique, to protect against heat damage. The microcapsules were subjected to high temperatures (120, 140, and 160°C) for 5 h. The protective effect of microcapsules on chlorophyll stability was assessed by measuring chlorophylls a and b degradation, total phenolic content, antioxidant activity, functional group analysis, colour, particle size, and morphology via scanning electron microscopy. Chlorophyll b significantly decreased by 87.78% in comparison with chlorophyll a (61.49%) during heating; the characteristic green colour of chlorophyll changed to brownish-green following heat exposure. However, chlorophyll was still present in the microcapsules as detected by the presence of the functional group C=O bond at 1600 nm wavelength. The heat treatment did not affect microcapsule particle size and morphology. Particle size distribution ranged from 91.58 to 112.51 µm, and the microcapsule was flake-shaped. The activation energy of chlorophyll a was 19336.96 kJ/mol·K; this was higher than that of chlorophyll b, which was 1780.53 kJ/mol·K. Based on the results, microcapsules produced using fish gelatine and Arabic gum as coating materials were able to protect chlorophyll in C. racemosa extract from heat damage.

The effect of high humidity hot air impingement blanching on the changes in cell wall polysaccharides and phytochemicals of okra pods

BACKGROUND

Okra pods contain heat-sensitive substances, such as phenolic compounds and other phytochemicals that can be degraded when okra pods are subjected to heat treatment. The understanding of the impact of high humidity hot air impingement blanching (HHAIB) on the changes in physicochemical properties of polysaccharides and phytochemicals of okra pods is of great importance because over-blanching may result in cell membrane disruption and changes in biologically active compounds under prolonged exposure to the thermal treatment. Therefore, the present study aimed to investigate the effect of HHAIB on the changes in physicochemical properties of pectins and phytochemicals extracted from okra pods.

RESULTS

Both the HHAIB time and method of extraction influenced their physicochemical characteristics and biological activity. Pectin fractions subjected to HHAIB were composed of polygalacturonic acid, rhamnogalacturonan, glucomannan, galactan, mannose, arabinose, rhamnose, calcium pectate and arabinogalactan. The contents of total phenolics, total flavonoids and antioxidant activity of extracts mostly increased during HHAIB (i.e. up to 19.0%, 13.2% and 35.3%, respectively). However, HHAIB reduced the chlorophyll-a (up to 55.7%) and lycopene (up to 52.6%) contents of okra pods.

CONCLUSION

The acquired knowledge may be useful for better understanding and optimization of technologies based on HHAIB treatment. The HHAIB treated okra can be a promising natural alternative in different applications, including its use as a replacement of some ingredients in food or non-food systems as a result of richness in polysaccharides and polyphenols, as well as high antioxidant properties. © 2022 Society of Chemical Industry.

Major lipophilic pigments in Atlantic seaweeds as valuable food ingredients: Analysis and assessment of quantification methods

Current trends towards the use of ingredients from natural origin in food, cosmetic and pharmaceutical industry, place macroalgae as a good reservoir of novel compounds. Among them, lipophilic major pigments such as chlorophylls and fucoxanthin, are of great interest because of their multiple applications as bioactive compounds and dyes. In this work, a mid-polarity medium was used to extract pigments from twenty-four species from North coast of Spain, including brown (Phaeophyceae) and red macroalgae (Rhodophyta). The fucoxanthin and chlorophyll a content was assessed by means of two different methods, spectrophotometric and high-performance liquid chromatography coupled to diode array detection (HPLC-DAD). The effect of dried processing on the pigment content of selected species was also evaluated. A linear relationship between the extractability of fucoxanthin and chlorophyll a was observed, being the highest content recorded among members belonging to the order Fucales and Undaria pinnatifida. This work provides good insights about the content on pigments in Spanish North Atlantic macroalgae with future commercial value in different industrial fields, as well as a critical overview of the suitability of the quantification methods and challenges related to their effect in results evaluation.

Effects of Different Zn2+ Concentrations and High Hydrostatic Pressures (HHP) on Chlorophyll Stability

This study provides a new idea for improving chlorophyll stability and color quality of green leafy vegetables by Zn2+ synergistic HHP. Zn-chlorophyll was prepared with zinc acetate and chlorophyll under HHP treatment. The effects of different zinc acetate concentrations and pressures on chlorophyll color, antioxidant activity, Zn2+ replacement rate, structure, and thermal stability were analyzed. Results showed with increased zinc acetate concentration and pressure, −a* value, antioxidant activity, and Zn2+ replacement rate of samples gradually increased. However, FTIR indicated the structure did not change. HHP fluorescence online analysis showed fluorescence intensity of samples decreased with zinc acetate concentration and pressure increasing. With zinc acetate 10 mg/100 mL and HHP 500 MPa, the highest −a* value (5.19), antioxidant activity (ABTS, DPPH, and FRAP were 37.03 g ACE/100 g, 25.95 g ACE/100 g, 65.43 g TE/100 g DW, respectively), and Zn2+ replacement rate (42.34%) were obtained. Thermal stability of Zn-chlorophyll obtained by synergistic effect was improved significantly.

THE POTENTIAL OF MATURE PANDAN LEAVES AS A SOURCE OF CHLOROPHYLL FOR NATURAL FOOD COLORANTS

Plant leaves are the primary source of natural colorants for food, mainly due to their chlorophyll content. However, the plant types and the degree of leaf maturity determine the quality and quantity of the chlorophyll. This study aimed to determine the best maturity level of pandan (Pandanus amaryllifolius Roxb.) leaves that serves as potential source of chlorophyll for natural food colorants. Eighty three pandan plants obtained from six different farming locations in Bantul Regency, Yogyakarta, Indonesia were used as samples. The leaves were grouped into four levels of maturity using descriptive statistics based on their morphology, anatomy, color, and chlorophyll contents. The results showed that the average number of leaves ranged from 20-24 leaves per plant (at 95% confidence interval), and 96.4% of the plant had a maximum of 24 leaves. The leaf maturity was grouped into (1) young, (2) medium, (3) mature, and (4) over mature, corresponding to leaf number 1-6, 7-12, 13-18, and 19-24, respectively. The higher the leaf maturity, the higher the chlorophyll content. However, the over mature leaves were only slightly different from the mature ones. In addition, pandan leaves have specific flavor and contain carotenoid, phenolic, and flavonoid substances. Anatomically, the mesophyll’s size was greatest in the mature leaves, while the size of chloroplast was not significantly different from medium to over mature leaves. Based on the chlorophyll content and mesophyll size, it was concluded that mature pandan leaves were the best source of chlorophyll, containing chlorophyll of 623.08 mg/100 g dry weight (DW).

Olive Tree Leaves—A Source of Valuable Active Compounds

The agricultural and processing activities of olive crops generate a substantial amount of food by-products, particularly olive leaves, which are mostly underexploited, representing a significant threat to the environment. Olive leaves are endowed with endogenous bioactive compounds. Their beneficial/health-promoting potential, together with environmental protection and circular economy, merit their exploitation to recover and reuse natural components that are potentially safer alternatives to synthetic counterparts. These biomass residues have great potential for extended industrial applications in food/dietary systems but have had limited commercial uses so far. In this regard, many researchers have endeavoured to determine a green/sustainable means to replace the conventional/inefficient methods currently used. This is not an easy task as a sustainable bio-processing approach entails careful designing to maximise the liberation of compounds with minimum use of (i) processing time, (ii) toxic solvent (iii) fossil fuel energy, and (iv) overall cost. Thus, it is necessary to device viable strategies to (i) optimise the extraction of valuable biomolecules from olive leaves and enable their conversion into high added-value products, and (ii) minimise generation of agro-industrial waste streams. This review provides an insight to the principal bioactive components naturally present in olive leaves, and an overview of the existing/proposed methods associated with their analysis, extraction, applications, and stability.

Stability of Chlorophyll as Natural Colorant: A Review for Suji (Dracaena angustifolia (Medik.) Roxb.) Leaves’ Case

Suji (Dracaena angustifolia (Medik.) Roxb.) leaves are famous chlorophyll source used as food colorant in Indonesia and other south-east Asian countries. Its chlorophyll has unique characteristics which can degrade through enzymatic and non-enzymatic reactions. This article summarizes traditional application of Suji leaves, the characteristics of Suji leaf chlorophyll, postharvest stability, and several ways to retain its green color. Potential development of Suji leaf extract as food colorant or food ingredients are also discussed.