Chlorophylls as Natural Bioactive Compounds Existing in Food By-Products: A Critical Review

Effect of Cowpea and Pumpkin Powders on the Physicofunctional Properties, Total Phenolic Content, Antioxidant Activity, and Consumer Acceptability of Soup

Cowpea (Vigna unguiculata) and pumpkin (Cucurbita maxima) play a pivotal role as affordable, nutritious food sources for humans. Low-income households can significantly benefit from supplementing their diet with nutritious and cost-effective locally available ingredients. The aim of this research was to develop a cost-effective soup formulation using ingredients that are readily available from a household garden and suitable for use in the kitchens of families with limited financial resources. The effect of cowpea and pumpkin powders on physicofunctional properties, total phenolic content (TPC), antioxidant activity (AA), and consumer acceptability of the soup were determined. Three composite soup mixes were prepared using various parts of cowpea and pumpkin at a ratio of 1:1. A control soup sample was developed, and the experimental soups were prepared by supplementing the control soup with 5%, 10%, or 15% of each composite soup mix, respectively. The physical properties, functional properties, TPC, AA, and consumer acceptability of soup were determined. The control soup had an appealing golden brown colour. Formulations 1 and 3 showed the highest relative viscosity (80.67-88.91 cP). All the experimental soup formulations had higher rehydration ratios (8-14.7 g/g) and water absorption capacities of 185.7-263.3 g/g compared to the control at 7.7 g/g and 65.7 g/g, respectively. The TPC of Formulation 2 (F2) (0.32-0.54 mg of gallic acid equivalent (GAE)/100 g powder) and Formulation 3 (F3) (0.54-0.63 mg GAE/100 g powder) was higher than Formulation 1 (F1) (0.25-0.32 mg GAE/100 g powder) and the control (0.44 mg GAE/100 g powder). Overall, the cowpea seed powder plus pumpkin fruit powder added at 10% in F2 appeared nearly optimal as a soup mix. It produced an attractive golden brown soup with increased swelling power (SP) and viscosity to assist in swallowing. Soup F1 and F2 scored high in appearance (7.27 and 7.0), aroma (7.1 and 6.7), taste (6.6 and 6.3), and overall acceptability (6.5 and 6.4). Despite having TPC and AA lower compared to F3, F2 containing 15% cowpea seed powder and pumpkin fruit has the potential to be further developed and commercialised due to the relatively high overall consumer acceptability and high acceptability in all sensory attributes.

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.

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

BACKGROUND

The 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).

RESULTS

Exposure 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.

CONCLUSION

Key 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.

Natural Pigments Recovery from Food By-Products: Health Benefits towards the Food Industry

Given the health risks associated with synthetic colorants, natural pigments have emerged as a promising alternative. These renewable choices not only provide health benefits but also offer valuable technical and sensory properties to food systems. The effective application of natural colorants, however, requires the optimization of processing conditions, exploration of new sources, and development of novel formulations to ensure stability and maintain their inherent qualities. Several natural pigment sources have been explored to achieve the broad color range desired by consumers. The purpose of this review is to explore the current advances in the obtention and utilization of natural pigments derived from by-products, which possess health-enhancing properties and are extracted through environmentally friendly methods. Moreover, this review provides new insights into the extraction processes, applications, and bioactivities of different types of pigments.

Acid-hydrolyzed phenolic extract of parsley (Petroselinum crispum L.) leaves inhibits lipid oxidation in soybean oil-in-water emulsions

The antioxidant activity of the natural phenolic extracts is limited in particular food systems due to the existence of phenolic compounds in glycoside form. Acid hydrolysis post-treatment could be a tool to convert the glycosidic polyphenols in the extracts to aglycones. Therefore, this research investigated the effects of an acid hydrolysis post-treatment on the composition and antioxidant activity of parsley extracts obtained by an ultrasound-assisted extraction method to delay lipid oxidation in a real food system (i.e., soybean oil-in-water emulsion). Acid hydrolysis conditions were varied to maximize total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. When extracts were exposed to 0.6 M HCl for 2 h at 80 ℃, TPC was 716.92 ± 24.43 µmol gallic acid equivalent (GAE)/L, and DPPH radical scavenging activity was 66.89 ± 1.63 %. Not only did acid hydrolysis increase the concentrations of individual polyphenols, but it also resulted in the release of new phenolics such as myricetin and gallic acid. The extract's metal chelating and ferric-reducing activity increased significantly after acid hydrolysis. In soybean oil-in-water emulsion containing a TPC of 400 µmol GAE/L, the acid-hydrolyzed extract had an 11-day lag phase for headspace hexanal compared to the 6-day lag phase of unhydrolyzed extract. The findings indicated that the conversion of glycosidic polyphenols to aglycones in phenolic extracts can help extend the shelf-life of emulsion-based foods.

Comparison of the effect of natural products and breast milk for preventing and treating nipple trauma and pain in lactating women: A systematic review and meta-analysis

INTRODUCTION

Prevention and management of nipple problems are crucial during the postpartum period for effective breastfeeding. Breastmilk is the most commonly recommended method for lactating women. However, insufficient studies have proven its superiority over other methods in the current literature. This study aims to determine the effects of natural products compared to breast milk in preventing and treating nipple trauma and pain in lactating women.

METHODS

In this review, we investigated studies from PubMed, Web of Science, Cochrane Library, MEDLINE, CINAHL, Scopus, and Google Scholar databases that met the inclusion criteria. We also assessed the studies' methodological quality with the Cochrane and JBI checklists. This study was performed based on the Guidelines of Systematic Reporting of Examination presented in the PRISMA checklist. The search protocol has been registered at the PROSPERO International Prospective Register of Systematic Reviews.

RESULTS

A total of ten published studies, including 1139 lactating women, were included in this review. The meta-analysis results showed a significant effect of natural product intervention on nipple trauma (Hedge's g -0.702, Q = 81,154, I2 =91,374 %, p < 0.001), soreness (Hedge's g =-0.648, Q = 7,092, I2 =71,801 %, p < 0.001), and pain levels (Hedge's g =-0.613, Q = 25,058, I2 =76,056 %, p < 0.001) experienced by lactating women.

CONCLUSION

The findings showed that natural products have greater potential than breast milk in managing nipple pain, trauma, and soreness. However, the evidence for these interventions is low or very low quality. Further research is needed to determine the most effective treatment for nipple trauma in lactating women.

An Eco-Friendly Supercritical CO2 Recovery of Value-Added Extracts from Olea europaea Leaves

An eco-friendly approach towards the recovery of value-added extracts from olive tree leaves with the aid of supercritical CO2 at 30 MPa was carried out. The impact of extraction temperature (35-90 °C) and presence of co-solvents (ethanol, water, and aqueous ethanol) on the total phenolic, flavonoid, and pigment content, as well as oleuropein, hydroxytyrosol, tyrosol, and α-tocopherol content was determined. In addition, the antioxidant activity of extracts from tree leaves using DPPH, ABTS, and CUPRAC assays was investigated. The results of the study showed that the most effective supercritical CO2 extraction was at 90 °C with an addition of ethanol, which enabled the separation of extract with the highest content of tested compounds. Some of the highest recorded values were for oleuropein 1.9 mg/g, for carotenoids 5.3 mg/g, and for α-tocopherol 2.0 mg/g. Our results are expected to contribute to the efforts towards the valorization of olive leaves as a sustainable source of valuable compounds, and boost local economies as well as the interest of pharmaceutical, food, and cosmetic industries for novel food by-product applications.

Ultrasound assisted extraction of phytochemicals from Piper betel L

Piper betel contains phytochemicals with diverse pharmacological effects. The objective of this study was to enhance the extraction efficiency of phytochemicals and the chlorophyll content using ultrasonication. The Box-Behnken design was employed to optimize the time (10, 20, 30 min), temperature (20, 30, and 40 °C), and solid-solvent ratio (1:10, 1:20, 1:30) by utilizing response surface methods with three independent variables. Multiple parameters, including extract yield, total phenol, total flavonoid, antioxidant activity, and chlorophyll content were used to optimize the conditions. The linear relationship between power intensity and responses was determined to be statistically significant, with a p-value less than 0.01. The interaction effect of temperature, time, and ratio of solid solvent was shown to be statistically significant (p < 0.05) for all the obtained results. The optimal parameters for achieving the highest extract yield were as follows: a temperature of 40 °C, a sonication time of 30 min, and a solid solvent ratio of 1:10. These conditions result in an extract yield of 21.99 %, a total flavonoid content of 44.97 mg/GAE, a total phenolic content of 185.05 mg/GAE, a DPPH scavenging activity of 99.1 %, and a chlorophyll content of 49.95 mg/ml. This study highlights the significance of customized extraction methodologies for optimizing the bioactive capacity of phytochemicals derived from betel leaves. The elucidation of extraction parameters and the resultant phytochemical profiles serves as a fundamental framework for the advancement of innovative pharmaceuticals and nutraceuticals, capitalizing on the therapeutic attributes of this traditional medicinal botanical.

Sulfated Nutrition Modifies Nutrient Content and Photosynthetic Pigment Concentration in Cabbage under Salt Stress

Negative effects of salt stress may be counteracted by adequate management of sulfated nutrition. Herein, we applied 3.50, 4.25, and 5.00 mM SO42- in a nutrient solution to counteract salt stress induced by 75 and 150 mM NaCl in cabbage cv. Royal. The increase in NaCl concentration from 75 to 150 mM reduced the contents of macronutrients and micronutrients in the shoot. When increasing from 3.50 to 4.25 mM SO42-, the contents of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) in shoots were enhanced, at both concentrations of NaCl. Increasing from 3.50 to 4.25 mM SO42- enhanced iron (Fe), zinc (Zn), manganese (Mn), and sodium (Na) concentrations with 75 mM NaCl. With 150 mM NaCl, the increase from 3.50 to 4.25 mM SO42- enhanced the contents of Cu and Mn, but also those of Na. Chlorophylls a, b, and total decreased as the concentration of SO42- increased in plants treated with 150 mM NaCl. With 75 mM NaCl, carotenoid concentration had a positive relationship with SO42-. Hence, the 4.25 mM SO42- concentration increased the contents of macronutrients and micronutrients in the presence of 75 mM NaCl, while, with 150 mM NaCl, it improved the contents of macronutrients except K. The chlorophyll a/chlorophyll b ratio remained close to 3 when the plants were treated with 5.00 mM SO42-, regardless of NaCl. Similarly, this level of SO42- increased the concentration of carotenoids, which translated into reductions in the total chlorophyll/carotenoid ratios, indicating a protective effect of the photosynthetic apparatus. It is concluded that higher doses of sulfur favor the accumulation of nutrients and increase the concentration of carotenoids under salt stress.

Evolution of Leaf Chlorophylls, Carotenoids and Phenolic Compounds during Vegetation of Some Croatian Indigenous Red and White Grape Cultivars

During the ripening process of grapes, the grapevine leaves are the most active green organs that are important for photosynthesis, which is closely linked to the development and metabolism of the plant. The detection of plant pigments and phenolic compounds in grapevine leaves can be a good indicator of the ageing process, vine vigor and the plant's ability to respond to fungal attack. In a one-year study, the development of leaf chlorophylls, carotenoids and phenolic compounds during the ripening of six indigenous Croatian grape cultivars and the international cultivars Merlot and Chardonnay was investigated. The chlorophyll a/b ratio and total chlorophyll and total carotenoid concentrations were also investigated. PCA was used to highlight relevant information from the data with the aim of distinguishing individual compounds based on the cultivar and phenological stage. The leaf total hydroxycinnamic acid and flavan-3-ol concentrations decreased slowly during grape development, with the highest concentration immediately after flowering and the lowest during grape ripening. The concentrations of β-carotene, lutein and xanthophylls tended to decrease during bunch closure or veraison, while the concentration of chlorophylls a and b peaked during veraison and then decreased during grape ripening. This research will provide an opportunity to select cultivars with the physiological adaptation to synthesize secondary metabolites that are important for managing stress conditions.

Ionic and nanoparticulate silver alleviate the toxicity of inorganic mercury in marine microalga Chaetoceros muelleri

Toxicological effects of silver nanoparticles (SNPs) in different organisms have been studied; however, interactions of SNPs with other environmental pollutants such as mercury are poorly understood. Herein, bioassay tests were performed according to ΟECD 201 guideline to assess the toxic effects induced by mercury ions (mercury chloride, MCl) on the marine microalga Chaetoceros muelleri in the presence of SNPs or silver ions (silver nitrate, SN). Acute toxicity tests displayed that the presence of SNPs or SN (0.01 mg L-1) significantly reduced the toxicity of MCl (0.001, 0.01, 0.1, 1, 10, and 100 mg L-1) and increased the IC50 of MCl from 0.072 ± 0.014 to 0.381 ± 0.029 and 0.676 ± 0.034 mg L-1, respectively. In the presence of SN or SNPs, the mercury-reducing effect on algal population growth significantly decreased. Considering the increase of IC50, the mercury toxicity decreased approximately 5.44 and 9.66 times in the presence of SNPs or SN, respectively. The chlorophyll a and c contents decreased at all exposures; however, the decrease by MCl-SNPs and MCl-SN was significantly less than MCl except at 1 mg L-1. The lowering effect of MCl-SN on chlorophyll contents was less than MCl and MCl-SNPs. MCl exposure induced significant raises in total protein content (TPC) at concentrations < 0.01mg  L-1, with a maximum of ~ 70.83% attained at 100 mg L-1. The effects of MCl-SNPs and MCl-SN on TPC were significantly less than MCl. Total lipid content (TLC) at all MCl concentrations was higher than the control, while at coexposure to MCl-SN, TLC did not change until 0.01 mg L-1 compared with the control. The effects of MCl-SN and MCL-SNPs on TPC and TLC were in line with toxicity results, and were significantly less than those of MCl individually, confirming their antagonistic effects on MCl. The morphological changes of algal cells and mercury content of the cell wall at MCl-SN and MCl-SNPs were mitigated compared with MCl exposure. These findings highlight the mitigatory impacts of silver species on mercury toxicity, emphasizing the need for better realizing the mixture toxicity effects of pollutants in the water ecosystem.

A critical review on the stability of natural food pigments and stabilization techniques

This comprehensive review article delves into the complex world of natural edible pigments, with a primary focus on their stability and the factors that influence them. The study primarily explores four classes of pigments: anthocyanins, betalains, chlorophylls and carotenoids by investigating both their intrinsic and extrinsic stability factors. The review examines factors affecting the stability of anthocyanins which act as intrinsic factors like their structure, intermolecular and intramolecular interactions, copigmentation, and self-association as well as extrinsic factors such as temperature, light exposure, metal ions, and enzymatic activities. The scrutiny extends to betalains which are nitrogen-based pigments, and delves into intrinsic factors like chemical composition and glycosylation, as well as extrinsic factors like temperature, light exposure, and oxygen levels affecting for their stability. Carotenoids are analyzed concerning their intrinsic and extrinsic stability factors. The article emphasizes the role of chemical structure, isomerization, and copigmentation as intrinsic factors and discusses how light, temperature, oxygen, and moisture levels influence carotenoid stability. The impacts of food processing methods on carotenoid preservation are explored by offering guidance on maximizing retention and nutritional value. Chlorophyll is examined for its sensitivity to external factors like light, temperature, oxygen exposure, pH, metal ions, enzymatic actions, and the food matrix composition. In conclusion, this review article provides a comprehensive exploration of the stability of natural edible pigments, highlighting the intricate interplay of intrinsic and extrinsic factors. In addition, it is important to note that all the references cited in this review article are within the past five years, ensuring the most up-to-date and relevant sources have been considered in the analysis.

Evaluation of light irradiation on anthocyanins and energy metabolism of grape (Vitis vinifera L.) during storage

Grape is the world's economic horticultural crop; it is perishable due to various pathogens and abiotic stress attributed to water loss-induced issues. To address these postharvest problems, this research investigates the effects of light irradiation on anthocyanins synthesis and energy metabolism in stored grapes to enhance their postharvest quality. The activities of chlorophyllase (1.17 U gk-1), Mg-dechelatase (351.69 U gk-1), chlorophyll-degraded peroxidase (3.49 U gk-1), and pheophytinase (0.85 U gk-1) were significantly higher in the control fruit than in the treated fruit at the end of storage. The red-light treatment showed higher levels of anthocyanins biosynthesis-related enzymes than green, blue-light, and control treatments. Additionally, light irradiation resulted in a decrease in adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, and energy charge. This was attributed to decreased activity of energy metabolism enzymes, reduced nicotinamide adenine dinucleotide phosphate content, and increased nicotinamide adenine dinucleotide content. These findings offer a theoretical foundation for optimizing grape coloration and energy metabolism during storage, thus prolonging the shelf-life of grapes by improving quality attributes. This research highlights the potential of light irradiation as a technique for enhancing the postharvest quality of agricultural products.

Enhancing phytochemical parameters in broccoli through vacuum impregnation and their prediction with comparative ANN and RSM models

Amidst increasing demand for nutritious foods, the quest for effective methods to enhance health-promoting attributes has intensified. Vacuum impregnation (VI) is a promising technique to augment produce properties while minimizing impacts on biochemical attributes. In light of broccoli's growing popularity driven by its nutritional benefits, this study explores the impact of VI using ascorbic acid and calcium chloride as impregnation agents on enhancing its phytochemical properties. Response surface methodology (RSM) was used for optimization of the vacuum impregnation process with Vacuum pressure (0.6, 0.4, 0.2 bar), vacuum time (3, 7, 11 min), restoration time (5, 10, 15 min), and concentrations (0.5, 1.0, 1.5%) as independent parameters. The influence of these process parameters on six targeted responses viz. total phenolic content (TPC), total flavonoid content (TFC), ascorbic acid content (AAC), total chlorophyll content (TCC), free radical scavenging activity (FRSA), and carotenoid content (CC) were analysed. Levenberg-Marquardt back propagated neural network (LMB-ANN) was used to model the impregnation process. Multiple response optimization of the vacuum impregnation process indicated an optimum condition of 0.2 bar vacuum pressure, 11 min of vacuum time, 12 min of restoration time, and 1.5% concentration of solution for vacuum impregnation of broccoli. The values of TPC, TFC, AAC, TCC, FRSA, and CC obtained at optimized conditions were 291.20 mg GAE/100 g, 11.29 mg QE/100 g, 350.81 mg/100 g, 1.21 mg/100 g, 79.77 mg, and 8.51 mg, respectively. The prediction models obtained through ANN was found suitable for predicting the responses with less standard errors and higher R2 value as compared to RSM models. Instrumental characterization (FTIR, XRD and SEM analysis) of untreated and treated samples were done to see the effect of impregnation on microstructural and morphological changes in broccoli. The results showed enhancement in the TPC, TFC, AAC, TCC, FRSA, and CC values of broccoli florets with impregnation. The FTIR and XRD analysis also supported the results.

Plant Food Dyes with Antioxidant Properties and Allergies-Friend or Enemy?

Color is an important food attribute which increases its attractiveness, thus influencing consumer preferences and acceptance of food products. The characteristic color of fresh, raw food is due to natural dyes present in natural food sources. Food loses its natural color during processing or storage. Loss of natural color (e.g., graying) often reduces the appeal of a product to consumers. To increase the aesthetic value of food, natural or synthetic dyes are added to it. Interestingly, the use of food coloring to enhance food attractiveness and appetizing appearance has been practiced since antiquity. Food coloring can also cause certain health effects, both negative and positive. Dyes added to food, both natural and synthetic, are primarily chemical substances that may not be neutral to the body. Some of these substances have strong antioxidant properties. Thanks to this activity, they can also perform important pro-health functions, including antiallergic ones. On the other hand, as foreign substances, they can also cause various adverse food reactions, including allergic reactions of varying severity and anaphylactic shock. This article discusses food dyes of plant origins with antioxidant properties (anthocyanins, betanins, chlorophylls, carotenoids, and curcumin) and their relationship with allergy, both as sensitizing agents and immunomodulatory agents with potential antiallergic properties.