Safety of Some Synthetic Food Colours: Review

Food additives are used to protect food, increase quality and extend shelf life in many stages, from production to consumption of food. Colorants added by food producers to color food or to adjust the color to desired level are among the commonly used food additives. Considering today's developing production technologies, foods fade or discolor at various stages of processing, storage, and sale due to physical and chemical conditions such as heat, light, pH and oxygen. Colorants are used to regain these color losses, to enhance weak colors, to give color to the food that is actually colorless, and to win back the favour of customers by hiding low quality. Therefore, the most used food colorants in Canada, China, European Union, Mexico and United States of America were presented. The chemical name, chemical structure, common uses, acceptable daily intake (ADI), and toxicity literature of six most used artificial food colors were reviewed.

Inactivation of MrPigH in Monascus ruber M7 Results in its Monascus Pigments Increase and Citrinin Decrease with mrpyrG Selection Marker

Monascus pigments (MPs) have been used as food colorants for several centuries in Asian countries and nowadays in the whole world via Asian catering. The MPs biosynthetic pathway has been well-illustrated, however, the functions of a few genes including mrpigH in the MPs gene cluster of M. ruber M7 are still unclear. In current study, mrpigH was disrupted in Δmrlig4ΔmrpyrG, a highly efficient gene modification system, using mrpyrG as a selection marker, and ΔmrpigHΔmrlig4ΔmrpyrG::mrpyrG and ΔmrpigHΔmrlig4ΔmrpyrG have been obtained. Subsequently, their morphologies, biomasses, MPs and citrinin (CIT) production were analyzed, respectively. These results have revealed that the deletion of mrpigH has significant effects on the morphology and growth of M. ruber M7. Moreover, compared with M. ruber M7, the yields of MPs and CIT were drastically increased and decreased in mrpigH mutants, respectively.

Chlorophyllin Inhibits Mammalian Thioredoxin Reductase 1 and Triggers Cancer Cell Death

Food colorants are widely used by humans in food production and preparation; however, their potential toxicity requires an in-depth analysis. In this study, five out of 15 commercial food colorants, namely, lutein, betanin, caramel, crocin and chlorophyll, significantly inhibited wild type selenoprotein thioredoxin reductase 1 (TrxR1, TXNRD1) in vitro. The hyperactive Sec498 residue of TrxR1 was targeted by those five colorants, which was confirmed by the site-directed mutagenesis of TrxR1. Furthermore, two colorants, chlorophyll and betanin, triggered the oligomerization of TrxR1. A chlorophyll-derived compound, chlorophyllin, irreversibly inhibited the 5,5′-dithiobis-2-nitrobenzoic acid (DTNB) reducing activity of TrxR1 with Kinact = 6.96 × 10−3 ± 0.49 × 10−3 µM−1 min−1. Moreover, chlorophyllin reduced the cellular TrxR activity, leading to reactive oxygen species (ROS) accumulation and, subsequently, promoting cancer cell death. In conclusion, this study might contribute to understand the food safety of commercial colorants and provide chemotherapeutic compounds by targeting TrxR1.

Effect of Different Food Coloring Additives on the Color Stability of Microabraded, at-Home Bleached and Resin Infiltrated Tooth

Objective: Color stability of at-home bleaching and resin infiltration is one of the main goals of these procedures. The primary aim of present study was to evaluate color stability of at-home bleaching and resin infiltration to four common colorants present in Indian foods (turmeric, beetroot, coffee and artificial food colorants). Materials and Methods: 128 human maxillary central incisors were used in this study. Teeth were randomly divided into groups as (i) subjected and (ii) not-subjected to microabrasion. Further, the teeth in each group (abraded/non-abraded) were randomly distributed to four subgroups (16 teeth/subgroup). Subgroups were control, bleached, combined treatment with at-home bleaching followed by resin infiltration and infiltrated. After treatment procedures the teeth were immersed in the four different food colorants. Objective photographic color change evaluation from pre-/ post staining was done using the CIEDE2000 formula. Statistical Analyses: Data were analyzed using parametric and nonparametric tests (α =0.05). Results: Turmeric solution caused significantly (P < 0.05) highest post-staining values b*and ΔE values in Combine-Rx group and Infiltration groups. Conclusions: Subsequent discoloration of esthetically treated teeth does not necessarily depend on the type of treatment but on the coloring additives present in the diet, of which turmeric has the highest discoloration potential. Clinical Significance: Turmeric is one of the essential ingredients in Indian foods therefore, both patients and operator must be aware that resin infiltrated teeth can discolored from regular diets that contains turmeric as coloring additives.

Encapsulation of Carotenoids as Food Colorants via Formation of Cyclodextrin Inclusion Complexes: A Review

The use of natural carotenoids as food colorants is an important trend of innovation in the industry due to their low toxicity, their potential as bio-functional ingredients, and the increasing demand for natural and organic foods. Despite these benefits, their inclusion in food matrices presents multiple challenges related to their low stability and low water solubility. The present review covers the main concepts and background of carotenoid inclusion complex formation in cyclodextrins as a strategy for their stabilization, and subsequent inclusion in food products as color additives. The review includes the key aspects of the molecular and physicochemical properties of cyclodextrins as complexing agents, and a detailed review of the published evidence on complex formation with natural carotenoids from different sources in cyclodextrins, comparing complex formation methodologies, recovery, inclusion efficiency, and instrumental characterization techniques. Moreover, process flow diagrams (PFD), based on the most promising carotenoid-cyclodextrin complex formation methodologies reported in literature, are proposed, and discussed as a potential tool for their future scale-up. This review shows that the inclusion of carotenoids in complexes with cyclodextrins constitutes a promising technology for the stabilization of these pigments, with possible advantages in terms of their stability in food matrices.