Characterization and Measurement of Anthocyanins by UV-Visible Spectroscopy

Chemical studies of anthocyanins: A review

http://www.uniroma2.it/didattica/piante_medicinali/deposito/Carotenoidi.pdf

Carotenoids and human health

Colour is an important quality attribute in the food and bioprocess industries, and it influences consumer’s choice and preferences. Food colour is governed by the chemical, biochemical, microbial and physical changes which occur during growth, maturation, postharvest handling and processing. Colour measurement of food products has been used as an indirect measure of other quality attributes such as flavour and contents of pigments because it is simpler, faster and correlates well with other physicochemical properties. This review discusses the techniques and procedures for the measurement and analysis of colour in food and other biomaterial materials. It focuses on the instrumental (objective) and visual (subjective) measurements for quantifying colour attributes and highlights the range of primary and derived objective colour indices used to characterise the maturity and quality of a wide range of food products and beverages. Different approaches applied to model food colour are described, including reaction mechanisms, response surface methodology and others based on probabilistic and non-isothermal kinetics. Colour is one of the most widely measured product quality attributes in postharvest handling and in the food processing research and industry. Apart from differences in instrumentation, colour measurements are often reported based on different colour indices even for the same product, making it difficult to compare results in the literature. There is a need for standardisation to improve the traceability and transferability of measurements. The correlation between colour and other sensory quality attributes is well established, but future prospects exist in the application of objective non-destructive colour measurement in predictive modelling of the nutritional quality of fresh and processed food products.

Colour Measurement and Analysis in Fresh and Processed Foods: A Review

Anthocyanins are flavonoids in fruits and vegetables that render them vivid red to blue. To date, there have been more than 635 anthocyanins identified in nature, featuring six common aglycones and various types of glycosylations and acylations. Dietary consumption of anthocyanins is high compared to other flavonoids, owing to their wide distribution in plant materials. Based upon many cell-line studies, animal models, and human clinical trials, it has been suggested that anthocyanins possess anti-inflammatory and anti-carcinogenic activity, cardiovascular disease prevention, obesity control, and diabetes alleviation properties, all of which are more or less associated with their potent antioxidant property. Evidence suggests that absorption of anthocyanins occurs in the stomach and small intestine. Epithelial tissue uptake seems to be highly efficient, yet transportation into circulation, tissue distribution, and urine excretion are very limited. The bioactivity of bioavailable anthocyanins should be a f...

Anthocyanins: Natural Colorants with Health-Promoting Properties

Nopal mucilage is a complex polysaccharide with great potential in the preparation of the films to food packaging. In this work, was develop a smart edible film with pH-indicating capabilities based on nopal mucilage, gellan gum, and red cabbage anthocyanins (70:20 w/w, and 10% respectively). Physical properties, appearance, and colorimetric functionality were characterized to pH range 2.5-5.9. Color stability, measured by CIELAB, was tested with different storage conditions and time and interpreted by differential tristimulus colorimetry. Results showed films whit uniform appearance, flexibility, easy-handling, and excellent color response within the pH range studied. The evolution of color difference (ΔE*ab) confirmed that the colorimetric functionality of films was stable at short storage periods (8 days) under natural conditions of sunlight and oxygen exposure, while a more extended storage period was affected. Results showed that the film is an excellent barrier and presents color changes triggered by pH changes.

/pdf/ph-indicating-properties-and-storage-stability-of-a-smart-463v5by4an.pdf

pH-indicating properties and storage stability of a smart edible film based on nopal-mucilage/gellan gum and red cabbage anthocyanins

Orange Juice Color: Visual Evaluation and Consumer Preference

A purification and fractionation process of the edible flowers of Tibouchina mollis and Tibouchina urvilleana followed by the first attempt to the anthocyanin and flavonol characterisation and identification by UHPLC-DAD-ESI-MS were developed. T. urvilleana exhibited a higher monomeric anthocyanin content, mainly due to the presence of the 3-O-(6′-p-coumaroyl)-glucoside derivatives of malvidin and petunidin. Quercetin-3-O-hexoside was the major flavonol identified in T. urvilleana, and the lack of myricetin derivatives was also exhibited. The anthocyanin and flavonol profile of T. mollis was more miscellaneous, characterised by the occurrence of cyanidin-3-O-glucoside followed by the 3-O-(6′-p-coumaroyl)-glucoside and 3-O-glucoside derivatives of malvidin and petunidin as anthocyanins, and myricetin, quercetin, and 3-O-hexosides of kaemperol and quercetin as flavonol compounds. Therefore, the anthocyanin and flavonol profile, through a process based on purification and fractionation, could be a useful tool to ensure the authenticity of the Tibouchina. Furthermore, the purification process made the antioxidant activity increase, which is greatly correlated to the reduction capacity. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/ijfs.15600

First accurate profiling of antioxidant anthocyanins and flavonols of
 Tibouchina urvilleana
 and
 Tibouchina mollis
 edible flowers aided by fractionation with Amberlite XAD‐7

The chemical composition of wine grapes changes qualitatively and quantitatively during the ripening process. In addition to the sugar content, which determines the alcohol content of the wine, it is necessary to consider the phenolic composition of the grape skins and seeds to obtain quality red wines. In this work, some imaging techniques have been used for the comprehensive characterisation of the chemical composition of red grapes (cv. Tempranillo and cv. Syrah) grown in a warm-climate region during two seasons. In addition, and for the first time, mathematical models trained with laboratory images have been extrapolated for using in field images, obtaining interesting results. Determination coefficients of 0.90 for sugars, 0.73 for total phenols, and 0.73 for individual anthocyanins in grape skins have been achieved with a portable hyperspectral camera between 400 and 1000 nm, and 0.83 for total and individual phenols in grape seeds with a desktop hyperspectral camera between 900 and 1700 nm.

/pdf/research-progress-in-imaging-technology-for-assessing-8ikddpyr.pdf

Research Progress in Imaging Technology for Assessing Quality in Wine Grapes and Seeds

The usefulness of digital image analysis in estimating sensory attributes of grape seeds in relation to maturation level was evaluated for the first time. Seeds from Syrah grapes harvested throughout the ripening period were grouped according to maturity using the DigiEye® system. The discriminant ability, homogeneity, repeatability, and uniformity of a sensory panel were assessed after training on grape seeds. The aim was to evaluate the use of digital image techniques in order to accurately establish the maturity level of grape seeds, based on sensory and textural features. All sensory attributes (color, hardness, cracking, vegetal, bitterness and astringency) showed significant (p < 0.05) correlations with the chemical maturity stage. Color and vegetal (sensory attributes), together with deformation energy (instrumental texture parameter) (De), allowed for the classification of the seeds into four real maturity stages, hence their usefulness as grape seed ripening indicators. Significant (p < 0.05) and high-correlation factors were also found between instrumental and sensory attributes. Therefore, digital analysis can be a useful tool to better define the maturity stage in the vineyard, and to dispose of grape seeds with well-defined sensory profiles for specific oenological applications. This could help to determine the optimal harvest date to manage winemaking, in order to produce high quality wines in warm climates.

Francisco J. Heredia

Papers

pH-indicating properties and storage stability of a smart edible film based on nopal-mucilage/gellan gum and red cabbage anthocyanins

Orange Juice Color: Visual Evaluation and Consumer Preference

First accurate profiling of antioxidant anthocyanins and flavonols of Tibouchina urvilleana and Tibouchina mollis edible flowers aided by fractionation with Amberlite XAD‐7

Research Progress in Imaging Technology for Assessing Quality in Wine Grapes and Seeds

Assessment of Sensory and Texture Profiles of Grape Seeds at Real Maturity Stages Using Image Analysis.