Degradation kinetics of anthocyanins from purple sweet potato (Ipomoea batatas L.) as affected by ascorbic acid

Preparation and characterization of intelligent packaging film for visual inspection of tilapia fillets freshness using cyanidin and bacterial cellulose

An intelligent pH-sensitive film was developed by incorporating cyanidin-3-glucoside (C3G) into bacterial cellulose (BC), and its application as a freshness indicator for tilapia fillets was investigated. The physical properties of the film were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results demonstrated the mechanical properties of the film were significantly changed due to higher crystallinity induced by C3G. XRD and FTIR analysis showed the increased crystallinity and transmittance intensity of the BC-C3G film. Moreover, this film exhibited distinctive color changes from red to green when exposed to buffers with a pH of 3 to 10. In accordance with changes in total volatile basic nitrogen (TVB-N) and total viable count (TVC) of tilapia fillets, the indicator demonstrated visualized color changes as rose-red (fresh), purple (still suitable), and lavender (spoiled) during storage at both 25 °C and 4 °C. The results suggest that this film has great potential to be used as an intelligent indicator to monitor the freshness of fish.

Kinetic study on peroxidase inactivation and anthocyanin degradation of black cherry tomatoes (Solanum lycopersicum cv. OG) during blanching

Introduction

Blanching is a necessary treatment stage in processing of tomato products to inactivate enzymes. However, it may cause the degradation of nutrients.

Objective

In this study, the kinetics of thermal peroxidase inactivation and anthocyanin degradation in black cherry tomatoes (cv. OG) were determined to predict the quality changes during the blanching.

Methods

Tomatoes were blanched at five levels of temperature (75–95oC) for five time periods (30–150 s).

Results

It was found that as the blanching temperature increased and the blanching time is prolonged, more peroxidase was inactivated and the greater number of anthocyanins was lost. The thermal peroxidase inactivation and anthocyanin degradation showed an apparent first-order reaction with the activation energy of 129.96 kJ/mol and 65.99 kJ/mol, respectively. Peroxidase and anthocyanin in black cherry tomatoes were found to be heat-sensitive.

Conclusion

These kinetic parameters were necessary to select and design appropriate blanching conditions for black cherry tomatoes on larger scale processing.

A Review of the Current Knowledge of Thermal Stability of Anthocyanins and Approaches to Their Stabilization to Heat

Anthocyanins are colored valuable biocompounds, of which extraction increases globally, although functional applications are restrained by their limited environmental stability. Temperature is a critical parameter of food industrial processing that impacts on the food matrix, particularly affecting heat-sensitive compounds such as anthocyanins. Due to the notable scientific progress in the field of thermal stability of anthocyanins, an analytical and synthetic integration of published data is required. This review focuses on the molecular mechanisms and the kinetic parameters of anthocyanin degradation during heating, both in extracts and real food matrices. Several kinetic models (Arrhenius, Eyring, Ball) of anthocyanin degradation were studied. Crude extracts deliver more thermally stable anthocyanins than purified ones. A different anthocyanin behavior pattern within real food products subjected to thermal processing has been observed due to interactions with some nutrients (proteins, polysaccharides). The most recent studies on the stabilization of anthocyanins by linkages to other molecules using classical and innovative methods are summarized. Ensuring appropriate thermal conditions for processing anthocyanin-rich food will allow a rational design for the future development of stable functional products, which retain these bioactive molecules and their functionalities to a great extent.

Optimization of the Drum Drying Parameters and Citric Acid Level to Produce Purple Sweet Potato (Ipomoea batatas L.) Powder Using Response Surface Methodology

Purple sweet potato (PSP) is a rich source of anthocyanins, but the anthocyanin content and color can be affected by the drying method and processing condition. Response surface methodology (RSM) with a Box-Behnken design (BBD) was used to investigate the effects of citric acid (CA) concentration, steam pressure (SP) and rotation speed (DS) on the physicochemical and functional properties of drum-dried purple sweet potato powder (PSPP). The anthocyanins of the PSPP were analyzed using mass spectrometry with electrospray ionization and twelve anthocyanins were identified. The results indicated that the moisture content (4.80 ± 0.17-9.97 ± 0.03%) and water activity (0.290 ± 0.004-0.47 ± 0.001) (p < 0.05) decreased with increasing drum temperature as well as with reduced drum rotating speed. CA had a significant (p < 0.05) effect on the color and total anthocyanin content (101.83 ± 2.20-124.09 ± 2.89 mg/100 g) of the PSPP. High SP and low DS negatively affected the antioxidant properties of the PSPP. DPPH value of the PSPP ranged from 20.41 ± 0.79 to 30.79 ± 1.00 μmol TE/g. The optimal parameters were achieved at 0.59% CA, 499.8 kPa SP and 3 rpm DS.

Combination of copigmentation and encapsulation strategies for the synergistic stabilization of anthocyanins

Copigmentation and encapsulation are the two most commonly used techniques for anthocyanin stabilization. However, each of these techniques by itself suffers from many challenges associated with the simultaneous achievement of color intensification and high stability of anthocyanins. Integrating copigmentation and encapsulation may overcome the limitation of usage of a single technique. This review summarizes the most recent studies and their challenges aiming at combining copigmentation and encapsulation techniques. The effective approaches for encapsulating copigmented anthocyanins are described, including spray/freeze-drying, emulsification, gelation, polyelectrolyte complexation, and their combinations. Other emerging approaches, such as layer-by-layer deposition and ultrasonication, are also reviewed. The physicochemical principles underlying the combined strategies for the fabrication of various delivery systems are discussed. Particular emphasis is directed toward the synergistic effects of copigmentation and encapsulation, for example, modulating roles of copigments in the processes of gelation and complexation. Finally, some of the major challenges and opportunities for future studies are highlighted. The trend of integrating copigmentation and encapsulation has been just started to develop. The information in this review should facilitate the exploration of the combination of multistrategy and the fabrication of robust delivery systems for copigmented anthocyanins.

Activated complex theory is a classical theory suitable for food science with appropriate use

Activated complex theory (ACT), apart from Van 't Hoff equation, has long been applying as an alternative tool to connect the kinetics (reaction rate constant, k) and thermodynamics parameters (including standard enthalpy of activation, △H⁺⁺; standard entropy of activation, △S⁺⁺; standard Gibbs free energy of activation, △G⁺⁺). The study mainly focuses on ACT application in food systems, especially oil and fruit juice processing. Considering there are several improper calculations or mistakes often found in papers published recently in 2014-2019, three considerations are presented when applying the ACT, including 1) Understand that the reaction should be a single chemical elementary step; 2) Ensure that the units used should be consistent; 3) Effectively analyze the kinetics and thermodynamic parameters by choosing proper temperatures. This study is expected to further improve the understanding and correct application of this well-known theory in future work.

Copigmentation with Chlorogenic and Ferulic Acid Affected Color and Anthocyanin Stability in Model Beverages Colored with Sambucus peruviana, Sambucus nigra, and Daucus carota during Storage

The food industry is looking for alternatives to synthetic colorants. Anthocyanins (ACNs) are suitable replacements due to their color characteristics and potential health benefits. The application of sauco (Sambucus peruviana, SP) as a potential source of ACN-based colorants was evaluated and compared to elderberry (Sambucus nigra, SN) and an extract from purple carrots (PC). Color and pigment stability were evaluated using a model beverage system during eight weeks of storage. Copigmentation with chlorogenic acid (CGA) and ferulic acid (FA) were also evaluated. SP ACNs provided darker and more intense colors than those obtained with SN but less intense than those obtained with PC. Addition of CGA and FA resulted in significantly darker colors with higher chroma in beverages colored with SP and SN but not in beverages colored with PC. Copigmentation with FA reduced monomeric pigment half-lives for all ACN sources but increased the chroma half-lives of beverages colored with SP and SN, from 23 to 49 weeks, and from 23 to 55 weeks, respectively. Analyses using liquid chromatography coupled to photodiode array detection and mass spectrometry showed that interaction between non-acylated ACNs and FA resulted in the formation of pyranoanthocyanins. Overall, ACNs from non-acylated sources such as SP, in combination with FA, showed potential for commercial food applications.

The Effect of Plant Additives on the Stability of Polyphenols in Cloudy and Clarified Juices from Black Chokeberry (Aronia melanocarpa)

Black chokeberry (Aronia melanocarpa) is a fruit with increasing popularity in consumption and processing. Recent research has strengthened the position of chokeberry as a source of phenolic compounds, antioxidants with high pro-health values, therefore it is important to investigate other substances protecting biologically active compounds during juice processing. This study was an attempt to reduce the loss of polyphenol in cloudy and clarified chokeberry juice by adding aqueous cinnamon and clove extracts. The results showed that the clarification of juices did not cause significant changes in the concentration of polyphenols. However, the addition of plant extracts prior to pasteurisation process influenced the content of phenolic compounds in the chokeberry juices. The main change in the composition of the chokeberry juices observed during storage was a result of the degradation process of anthocyanins. The research showed that, despite the common view about the beneficial effects of polyphenols and other compounds exhibiting mutual antioxidative potential, it is very difficult to inhibit the degradation process.

Synergistic Effects of Mild Heating and Dielectric Barrier Discharge Plasma on the Reduction of Bacillus Cereus in Red Pepper Powder

The synergistic efficacy of a combined treatment of mild heat (MH) and dielectric barrier discharge (DBD) plasma in Bacillus cereus-contaminated red pepper powder was tested. A cocktail of three strains of B. cereus (NCCP 10623, NCCP 14579, ATCC 11778) was inoculated onto red pepper powder and then treated with MH (60 °C for 5-20 min) and DBD plasma (5-20 min). Treatment with MH and DBD plasma alone for 5-20 min resulted in reductions of 0.23-1.43 and 0.12-0.96 log CFU/g, respectively. Combined treatment with MH and DBD plasma was the most effective at reducing B. cereus counts on red pepper powder, and resulted in log-reductions of ≥ 6.0 log CFU/g. The largest synergistic values (4.24-4.42 log) against B. cereus in red pepper powder were obtained by the combination of 20 min MH and 5-15 min DBD plasma. The values of Hunter color ''L'', ''a'', and ''b'', were not significantly different from those of the untreated sample and that with the combination of MH (60 °C for 5-20 min) and DBD plasma (5-20 min). Also, no significant (p > 0.05) differences in pH values between samples were observed. Therefore, these results suggest that the combination of MH treatment and DBD plasma can be potentially utilized in the food industry to effectively inactivate B. cereus without incurring quality deterioration of red pepper powder.

Ascorbic Acid Derivatives as Potential Substitutes for Ascorbic Acid To Reduce Color Degradation of Drinks Containing Ascorbic Acid and Anthocyanins from Natural Extracts

Ascorbic acid is widely used in the food industry as a source of vitamin C or as antioxidant. However, it degrades quickly in beverages at acidic pH and can accelerate the degradation of anthocyanins, natural dyes used in beverages, leading to a loss of color. In this work, we investigated the possibility to replace ascorbic acid by ascorbic acid derivatives to prevent its degradation effect on anthocyanins from natural extracts (black carrot, grape juice, and purple sweet potato). For this, the thermal and photolytic stabilities under air and under N₂ of ascorbic acid (as reference) and of some ascorbic acid derivatives (3-O-ethyl-l-ascorbic acid, 2-O-α-d-glucopyranosyl-l-ascorbic acid, l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate, l-ascorbyl 2,6-dibutyrate, glyceryl ascorbate, (+)-5,6-O-isopropylidene-l-ascorbic acid), soluble in aqueous model beverages, were studied alone and in the presence of anthocyanins from the natural extracts in citrate buffer at pH 3. The stability was followed by UV-visible spectrometry. To extend the investigation, some properties of the ascorbic acid derivatives (pK_a, oxidation potential, bond dissociation energy, ionization potential) were also determined. Moreover, the addition of chlorogenic acid was examined to further stabilize the mixture of anthocyanins with 2-O-α-d-glucopyranosyl-l-ascorbic acid, a promising ascorbic acid derivative.

Enhanced Chemical Stability, Intestinal Absorption, and Intracellular Antioxidant Activity of Cyanidin-3-O-glucoside by Composite Nanogel Encapsulation

A composite nanogel was developed for cyanidin-3-O-glucoside (C3G) delivery by combining Maillard reaction and heat gelation. The starting materials utilized were ovalbumin, dextran, and pectin. C3G-loaded nanogel was spherical with a diameter of ∼185 nm, which was maintained over a wide range of pH and NaCl concentrations. The composite nanogel enhanced the chemical stability of C3G under accelerated degradation models and a simulated gastrointestinal tract. Clathrin-mediated, caveolae-mediated, and macropinocytosis-related endocytosis contributed to the higher cellular uptake of nano-C3G than that of free-C3G. The apparent permeability coefficients of C3G increased 2.16 times after nanoencapsulation. The transcytosis of the C3G-bearing nanogel occurred primarily through the clathrin-related pathway and macropinocytosis and followed the "common recycling endosomes-endoplasmic reticulum-Golgi complex-basolateral plasma membrane" route. Moreover, nano-C3G was more efficient in restoring the viability of cells and activities of endogenous antioxidant enzymes than free-C3G in oxidative models, which may be attributed to the former's high cellular absorption.

The Influence of Chemical Structure and the Presence of Ascorbic Acid on Anthocyanins Stability and Spectral Properties in Purified Model Systems

The loss of color pigment is an important quality factor of food products. This work aimed to systematically study, in purified model systems, the influence of anthocyanins' structure (by increasing the size of the conjugated sugar) and the presence of ascorbic acid on their stability and spectral properties during storage at two pH levels relevant to medium and high acid foods (6.5 and 4.5, respectively). Anthocyanins (cyanidin (Cy), cyanidin 3-O-β-glucoside (Cy3G) and cyanidin 3-O-β-rutinoside (Cy3R)) displayed first-order degradation rates, presenting higher stability in acidic medium and enhanced stability with increasing size of conjugated sugar. The addition of ascorbic acid resulted in significantly enhanced degradation. Changes in ultra violet visible (UV-VIS) spectral properties presented a decrease in typical color intensity and pointed towards formation of degradation products. Identification and kinetics of formation for cyanidin degradation products were obtained by high performance liquid chromatography system-mass spectrometry (HPLC-MS).

Thermal and Photochemical Stability of Anthocyanins from Black Carrot, Grape Juice, and Purple Sweet Potato in Model Beverages in the Presence of Ascorbic Acid

Anthocyanins are natural dyes widely used in the food industry, but their chemical stability in beverages can be affected by the presence of additives. In the present paper, the interaction between anthocyanins and ascorbic acid (AA) is more particularly investigated. Ascorbic acid is an ubiquitous component in food products. In this study, the thermal stability at 43 °C and the photolysis stability in air and in an inert atmosphere (N₂) of anthocyanins extracted from black carrot (BC), grape juice (GJ), and purple sweet potato (SP) were studied in the presence and absence of ascorbic acid (in citrate buffer at pH 3). Discriminating the main environmental factors (i.e., heat and light) affecting anthocyanin stability is a key point for better understanding the degradation pathways. The stability of the anthocyanins was followed by UV-vis spectrometry. Moreover, to understand the degradation mechanisms in both the presence and absence of ascorbic acid, various techniques such as fluorescence quenching, cyclic voltammetry, and electron-spin-resonance (ESR) spectroscopy were also used to furnish a full coherent picture of the chemical mechanisms associated with the anthocyanin degradation. In addition, molecular orbitals and bond-dissociation energies (BDE) were calculated to extend the investigation. Moreover, the effects of some supplementary stabilizers (chlorogenic acid, sinapic acid, tannic acid, fumaric acid, β-carotene, isoquercitrin, myricitrin, green coffee bean extract, and rosemary extract) and sugars (sucrose, fructose, and glucose) on anthocyanins stability in the presence of ascorbic acid were examined.

Thermal Behavior of Sweet Potato Starch by Non-Isothermal Thermogravimetric Analysis

In this study, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) methods were used to study the structure, the thermal degradation kinetics, and the thermogram of sweet potato starch, respectively. The thermal decomposition kinetics of sweet potato starch was examined within different heating rates in a nitrogen atmosphere. Different models of kinetic analysis were used to calculate the activation energies using the thermogravimetric data of the thermal degradation process. The activation energies got from Kissinger, Flynn–Wall–Ozawa, and Šatava–Šesták models were 173.85, 174.87, and 174.34 kJ·mol⁻¹, respectively. Thermogravimetry–Fourier transform infrared spectroscopy (TG-FTIR) analysis showed that the main pyrolysis products included water, carbon dioxide, and methane.

Stabilization of natural colors and nutraceuticals: Inhibition of anthocyanin degradation in model beverages using polyphenols

Anthocyanins are widely used as natural colorants in foods, but they are highly susceptible to chemical degradation during storage leading to color fading. This study examined the potential of natural quillaja saponin and polyphenols (vanillin, epigallocatechin gallate, green tea extract, and protocatechualdehyde) at inhibiting color fading of anthocyanins in model beverages. The purple carrot anthocyanin (0.025%) in model beverages (citric acid, pH 3.0) containing l-ascorbic acid (0.050%) degraded with a first-order reaction rate during storage (40°C/7days in light). The addition of polyphenols (0.2%) delayed color fading, with the most notable improvement observed with green tea extract addition. The half-life for anthocyanin color fading increased from 2.9 to 6.7days with green tea extract. Fluorescence quenching measurements showed that the green tea extract contained components that interacted with anthocyanins probably through hydrophobic interactions. Overall, this study provides valuable information about enhancing the stability of anthocyanins in beverage systems using polyphenols.

Gallic acid as a protective antioxidant against anthocyanin degradation and color loss in vitamin-C fortified cranberry juice

The objective of this study was to evaluate different antioxidants for anthocyanin (ACY) retention in vitamin C fortified cranberry juice and assess its quality. Cranberry juice was fortified with 40-80mg/100mL vitamin C and added hesperidin, catechin, and gallic acid at different concentrations. Juice was pasteurized at 85°C for 1min and stored at 23°C for 16days. ACYs, vitamin C, color intensity, and browning index (BI) were evaluated at 2-day intervals. Gallic acid was found to be the most effective antioxidant against ACYs degradation and significantly (p<0.05) increased red color intensity by 37% and ACY concentration by 41%, compared to the control. After 16-day storage, the BI of gallic acid-added juice was significantly lower (0.80 vs 1.00) than the control juice. The outcome of this research provided a potential solution of using gallic acid to preserve a health-beneficial component (ACYs), and endogenous red color in cranberry juice.

Enhanced stability of anthocyanin-based color in model beverage systems through whey protein isolate complexation

Anthocyanins are often used in functional foods and beverages as colorants and nutraceuticals. However, these natural compounds may undergo chemical degradation during storage leading to color fading and loss of bioactivity. In particular, vitamin C (l-ascorbic acid) is known to accelerate anthocyanin degradation. In this study, the influence of various food-grade biopolymers on the physical and chemical stability of model beverages containing anthocyanin (0.025%), ascorbic acid (0 or 0.05%), and calcium salt (0 or 0.01%) was examined under accelerated conditions (40°C for 7days). Four biopolymers (1%) were examined for their potential to inhibit anthocyanin degradation: native whey protein; denatured whey protein; citrus pectin; and beet pectin. The physical stability was determined by measuring changes in absorbance, color, and visual appearance. Solutions containing anthocyanin and calcium salt (0 or 0.01%) were stable throughout storage, while those with added ascorbic acid were the least stable. The addition of biopolymers, particularly heat denatured whey protein, significantly enhanced the stability of the anthocyanin during storage. Fluorescence quenching studies showed that the anthocyanin may have formed complexes with the whey protein through hydrogen bonding that resulted in their enhanced stability in the presence of ascorbic acid. This study provides information that may improve the stability of anthocyanins in food and beverage systems.