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Agricultural waste and food sources are some of the pollutants of the environment. One of these wastes is the peel of fruits that cannot be consumed as food. In this regard, walnut husk (WH) and oleaster peel (PO) are known as two important sources of tannin and are bulky wastes. Because of the high percentage of tannin, these materials can be used as a natural source for the preparation of bio-mordant in the dyeing process.

In this study, Reseda and Madder were used as natural dyes in the presence of a mixture of two bio-mordants. WH and PO were selected as bio-mordant. All natural resources are extracted to obtain the juice. The phenolic percentage of tannin-containing extracts was evaluated and then it was used for wool yarns by premordanting method. The results of evaluating the fastness properties using the ISO method.

The most important achievement of this research is the use of agricultural waste in the dyeing process to reduce environmental pollution and create added value. All compounds rich in tannin have some phenolic components, therefore the amount of phenolic content of these extracts was evaluated. The effect of mixing the mordant on the color characteristics of the yarns was investigated and the results showed that changing the ratio of the combination of two mordant is effective on the K/S values. The results of evaluating the fastness properties using the ISO method showed that the washing, rubbing and light fastness in the presence of mordant is good, good and moderate, respectively.

In this paper, to the best of the authors’ knowledge, for the first time, the combination of two natural extracts obtained from agricultural waste has been used to create a new bio-mordant on fibers and improve stability.

The purpose of this study is to address consumer’s preference of natural pigments over synthetic ones and their use in various product developments rather than using synthetic colours. A budding interest of using natural pigments has made researchers to explore several techniques for their stabilization and application in different food products.

In this review, four major natural pigments with potential health benefits have been studied. Betalins, carotenoids, anthocyanins and chlorophylls, in spite of having excellent bio-functional and therapeutic profile, are found to be unstable. Therefore, various nanoencapsulation techniques are used to increase their stability along with their therapeutic properties.

Nanoencapsulation of natural pigments improves their stability, their effect on therapeutic properties and their application in different food products. These findings could be attributed to the encapsulating material as it acts as a barrier and ushers changes in the matrix of natural pigments. Also, nanoencapsulation not only increases stability but also provides several health benefits such as anti-inflammation, anti-cancer, anti-allergic and anti-thrombotic properties.

This paper highlights the openings for the use of nanoencapsulation of natural pigments to stabilize them and use them as a potential colourant and functional ingredient in different food products. Phenols, carotenoids and antioxidant activity are the major factors that are responsible for promoting several health benefits.

This study aims to investigate the effect of spray drying temperature and maltodextrin addition on the contents of phenolics, flavonoids, anthocyanins and antioxidant activities (2,2-diphenyl-1-picrylhydrazyl [DPPH] radical scavenging activity, ferric reducing antioxidant power and reducing power) of karonda powder.

Over the past few decades, the demands for application of natural colorants in food production have been attracting the attention of academic research and food industry. Anthocyanins, a red pigment commonly found on plants, show high potentials in the preparation of spray-dried pigment powder. This study, therefore, was conducted using full factorial design with two factors, namely, inlet temperature (150°C and 160°C) and soluble solid concentration (10, 15 and 20°Brix) with maltodextrin as carrier to produce pigment powder from karonda, an anthocyanin-rich fruit which is native to southeast Asia.

Increasing soluble solid content from 10 to 15°Brix resulted in a 42%–57% reduction in phenolic, flavonoid and anthocyanin contents. However, when increasing the amount of maltodextrin from 15 to 20°Brix, a lower reduction (approximately 11%–19%) was observed. In samples with the same °Brix, there was no significant variation in antioxidant contents and activities, especially at high maltodextrin ratios. In addition, the reducing power of samples dried at higher temperature (160°C) was higher than that of samples dried at lower temperature. Karonda spray-dried powder showed a good positive correlation (p < 0.01) between antioxidant contents and DPPH• activity.

To the best of the authors’ knowledge, in this study, for the first time, the effect of spray drying conditions on the quality of karonda powder was investigated.