Roselle anthocyanin stability profile and its potential role in post-harvest deterioration: A review

The conversion of roselle calyx into a dried extract without decreasing its consistency is a challenge, given the perishability of the calyx and instability of anthocyanin, which can quickly degrade and develop colored or unwanted brown colors because of its high reactivity. The most critical factors influencing anthocyanins' stability are pH, temperature, light and post-harvest-related enzymes. Besides, the calyx suffered wound injury when removing seed from the calyx, causing stress and eventually, microbial degradation. Nonetheless, mature anthocyanins stimulate plants by responding to stress, especially drought, high salinity, excess light and injury; it is also correlated with improved stress resistance as the genes of individual plants are triggered under these conditions modulate anthocyanin biosynthesis. This work investigates the stability and potential role of roselle anthocyanin in post harvest deterioration. Anthocyanin stability can, therefore, be achieved by maintaining low pH and temperature, acylation, glycosylation, copigmentation and encapsulation. In the quest for roselle deterioration biomarkers, the detection of critical enzymes, such as Chalcone synthase CHS and FH3 Flavanone 3 hydroxylase, would offer insight into the genetic modification of anthocyanin.

A Review on Anthocyanin Pigments with respect to its Nutraceutical Properties

Anthocyanin pigments are readily degraded during processing and storage of foodstuffs that can have a dramatic impact on color quality and may also affect the nutritional properties. Total anthocyanin pigment content and indices for polymeric color and browning are easily measured with simple spectrophotometric methods. Once individual pigments are identified, their changes can be monitored by high-performance liquid chromatography (HPLC). The edible fruits of 12 plants were extracted in methanol and subjected to solvent–solvent partitioning to yield three fractions, hexane, ethyl acetate, and aqueous. A number of factors affecting anthocyanin stability and color are discussed in this review. Anthocyanins are probably the most spectacular of plant pigments since they are responsible for most of the red, purple and blue pigmentation of flowers, hits and vegetables. However, because of their highly reactive nature, anthocyanins readily degrade, or react with other constituents in the media, to form colorless or brown colored compounds. The presence of an oxonium ion adjacent to carbon 2 makes the anthocyanins particularly susceptible to nucleophilic attack by such compounds as sulfur dioxide, ascorbic acid, hydrogen peroxide and even water. Loss of anthocyanin pigmentation also occurs in the presence of oxygen and various enzymes, and as a result of high temperature processing. Certain degree of pigment stabilization may be conferred by acylation with various organic acids, co pigmentation, self-association and/or metal chelation. In addition, pH has a marked effect on anthocyanin stability, and on the color of media containing these pigments. A number of anthocyanin-rich sources have been investigated for their potential as commercial pigment extracts. Although their application is primarily limited to acidic media, continued research on the chemistry of anthocyanins may lead to application and stabilization of these pigments in a wider variety of food products.

Anthocyanin Stability Profile of Mango Powder: Temperature, pH, Light, Solvent and Sugar Content Effects

Anthocyanins, a major natural food colorant rich in mango powder, need considerable protection during processing and storage for better retention due to colour instability. The purpose of the study is to evaluate the stability of the anthocyanin’s extracts obtained from cabinet dried mango powder under different factors which could disrupted the anthocyanin pigments during processing. The factors are processing temperature and time (30°C, 60°C and 80°C for 10, 20 and 30 minutes each, respectively), storage conditions (room temperature, refrigerator temperature and freezing temperature), pH (2, 3, 4, 7 and 10), oxygen, influence of light, different extraction solvent (methanol, absolute ethanol, acidified ethanol (1%), and 50% KMS -Ethanol), sugar level (20%, 40%, and 60%). The intensity of the extracted colour was measured at wavelength 520 nm using UV-VIS spectrophotometer. The results can elucidate the increasing heating temperature and time, sugar content, and exposure to light is able to spoil the anthocyanin molecule. There was a proportional effect of pH and oxygen. The anthocyanin stability was found better in pH=10, acidified ethanol (1%) as extracting solvents, absence of light as processing condition and refrigeration temperature as storage temperature. Hence, these findings could be useful in the food industry to choose a proper processing condition for development of mango powders-based products for satisfying the consumer perception by retaining anthocyanin pigment.