Natural colorants from vegetable food waste: Recovery, regulatory aspects, and stability-A review.

Worldwide, approaches inspired by the Circular Economy model have been increasing steadily, generating new business opportunities such as the recovery of high-added value molecules (e.g., pigments) from vegetable food waste that may be applied as food additives (e.g., colorants). Indeed, food waste is a global problem that does not seem to be decreasing, leading to economic, environmental, and social issues. Moreover, synthetic dyes have been associated with adverse effects on human health, encouraging research to explore much safer, natural, and eco-friendly pigments. This state-of-the-art review gives a brief overview of the regulatory aspects concerning food waste, Circular Economy, and natural versus synthetic colorants. We have critically reviewed the recent advances in pigment recovery from vegetable food waste bringing back the green/unconventional extraction methods. Among them, enzyme-assisted extraction as a depth feature technique is highlighted, given that it allows the recovery of pigments in a mild, selective, efficient, and sustainable way. Furthermore, the stability issue of the different natural colorants has been critically discussed in relation to the extraction and application conditions. Several and tailored stabilization methods have been described and reported for each pigment although additional research is necessary on their long-lasting stabilization and utilization in food matrices. PRACTICAL APPLICATION: This review focuses on the main types of natural pigments in vegetable food waste, their legislative framework, extraction technologies and strategies to improve the stability , as well as their possible applications.

Betalain Extracts from Beetroot as Food Colorants: Effect of Temperature and UV-Light on Storability.

Beetroot is a good source of natural food colorants given that it contains significant amount of betalain pigments. This study investigates the three-months storage stability of betalain extracts recovered from unsold beetroot by a specific enzymatic mix. The extract storability was evaluated by the kinetic degradation model of betacyanins and betaxanthins, as well as by pigment color attributes (CIELa*b* parameters) under dark and UV-light exposure at different temperatures (4, 25 and 40 °C). Considering all the tested storage conditions, betaxanthins appeared to be more stable than betacyanins in terms of degradation rate constant, half-life time and activation energy. The effect of UV-light was negligible if the pigment was not exposed to temperatures higher than the room one, since no relevant differences were found between the parameters studied at 4 and 25 °C. Taking into account the visual color, all the investigated color indexes (total color difference, chroma and hue) were mainly affected by temperature, even if mildly high (40 °C), and to a lesser extent by UV-light exposure.

'Il Sonnambulo' by Michele Carafa: A Forgotten Romantic Opera with Sleepwalking.

Romantic operas provide a useful tool for historians to understand the perception of some medical disorders that existed during the nineteenth century. Somnambulism was still a mysterious condition during this time, since its pathogenesis was unknown. Hence, it comes as no surprise that somnambulism features in a number of operas, the best known of which are Verdi's 'Macbeth' and Bellini's 'La Sonnambula', both the subject of recent scholarship. Here we examine a more obscure opera in which sleepwalking is depicted. Dating from 1824, 'Il Sonnambulo' by the Italian composer Michele Carafa is based on a libretto by Felice Romani. Although it shares some features with the Verdi and Bellini operas, it also presents original elements. Our analysis of this forgotten opera supports the contention that studying operas can shed light on medical theories and practices, and on how ideas about mind and body disorders were transmitted to the laity in times past.

Stabilized chlorophyll-based food colorants from spinach: Kinetics of a tailored enzymatic extraction.

An organic solvent-free method based on limited dosing options (biocatalyst and zinc chloride) for the quick and mild recovery of chlorophyll (Chl) from spinach has been proposed. This tailored, custom-made protocol has been designed to produce stable green natural colorants. The kinetics of pigment extraction turned out to be a very useful tool to identify the proper conditions, in terms of biocatalyst dose (0.10-50 U/g), extraction time (1-48h), and ZnCl2 amount (50-300ppm), both for enhancing the recovery yield and preserving the green color. Considering the extraction kinetics, the recovery yield, and the colorimetric data, the suitable conditions to produce stable green and food-grade colorants are 0.10 U/g of enzyme, 3h, and 150ppm of ZnCl2 at 25°C. The extraction yield of Chl (4863µg/U) was about 51% greater than control, with a higher extraction rate constant (5.43 × 10-4 g/(µg min)). Considering the impact of ZnCl2 amount on Chl, its protective action resulted to be more noticeable toward Chl a: at 150ppm, an increased amount of about 2.5 and 1.5 times was found for Chl a and Chl b, respectively, in comparison to the reference (0ppm ZnCl2). PRACTICAL APPLICATION: This research demonstrates how a suitable kinetic approach helps to provide a tailored protocol, customized for the vegetable matrix, to produce stable green natural colorants from spinach. Lowering enzyme dosage and ZnCl2 amount during the extraction of chlorophyll at low temperature is crucial for its potential use as a colorant in food industry, providing high economic values through saving time and environmental protection.

Enzyme-Assisted Extraction for the Recovery of Food-Grade Chlorophyll-Based Green Colorant.

The aim of the study was to develop a biotechnological approach for the green recovery of chlorophyll from spinach, to be used as a natural food colorant. The plant matrix was characterized in terms of cell wall polysaccharide composition, and a tailored enzymatic mix based on cellulase (40%) xylanase (41%) and polygalacturonase (19%) was formulated. The process variables (temperature (°C), time (h), enzyme mix dose (U/g), zinc concentration (ppm), and buffer/substrate ratio (B/S)) and their interactions were studied by response surface methodology. The overlay plot made it possible to identify the process conditions (T: 25 °C, Zn: 150 ppm e B/S: 17.5, t: <2 h and enzyme mix dose between 12 and 45 U/g) to maximize the amount of chlorophyll, and concurrently, the quality of the green color of the extract. Finally, the novel colorant was applied in the production of a real food.

Phenolic-Degrading Enzymes: Effect on Haze Active Phenols and Chill Haze in India Pale Ale Beer.

The development of green and sustainable biotechnological approaches for preventing chill haze formation is currently under investigation. In this preliminary study, laccase and tannase (pure or combined) were applied as phenolic-degrading enzymes during two crucial brewing steps (i. post-mashing and ii. before the yeast inoculum). In post-mashing and irrespective of the dosage applied (100 µL/L or 1 mL/L), tannase-based treatment ensured the complete removal of haze active (HA) phenols, which was proved by the full prevention of chill haze (about 1 EBC vs. 22 EBC in the control sample). Before yeast inoculum for the alcoholic fermentation, the removal of haze active phenols and the prevention of chill haze were both tannase-dosage-dependent (15 and 2 EBC for the lowest and the highest dosages, respectively) although they failed to completely break down the HA phenols. This biotechnological approach did not significantly affect the chromatic properties of treated beer.

A Minimally Invasive Approach for Preventing White Wine Protein Haze by Early Enzymatic Treatment.

Protein stability in bottled white wine is an essential organoleptic property considered by consumers. In this paper, the effectiveness of an early enzymatic treatment was investigated by adding a food-grade microbial protease at two different stages of winemaking: (i) at cold settling, for a short-term and low temperature (10 °C) action prior to alcoholic fermentation (AF); (ii) at yeast inoculum, for a long-lasting and medium temperature (18 °C) action during AF. The results reveal that protease sufficiently preserved its catalytic activity at both operational conditions: 10 °C (during cold settling) and 18 °C (during AF). Furthermore, protease addition (dosage 50-150 µL/L) raised the alcoholic fermentation rate. The treatment at yeast inoculum (dosage 50 µL/L) had a remarkable effect in preventing haze formation, as revealed by its impact on protein instability and haze-active proteins. This minimally invasive, time and resource-saving enzymatic treatment, integrated into the winemaking process, could produce stable white wine without affecting color quality and phenol content.

Inclusion of curcumin in b-cyclodextrin: a promising prospective as food ingredient.

In the present work, the inclusion complexes between curcumin (CC) and ß-cyclodextrin (ß-CD) were obtained through co-precipitation at different times of magnetic stirring and simple mixing. The stoichiometric ratio between CC and ß-CD was ascertained to be 1:2. The samples prepared by co-precipitation (24 h magnetic stirring and 24 h cold static precipitation) and by simple mixing, showed the best performance in terms of powder recovery (72 and 97%, respectively), encapsulation efficiency (72 and 95%, respectively) and tinting power, while no significant differences were revealed in terms of loading capacity (about 14%). Using either inclusion method, the complexation of CC into ß-CD make the colorant 20-fold more water soluble than pure CC. The pigment stability was also enhanced under different storage conditions (high temperature and light exposure), either when applied in liquid or gel state. However, after 30 days under natural light exposure, an appreciable colour change from yellow to orange was revealed to an extent probably perceptible by an inexperienced observer.

A Novel Process for the Recovery of Betalains from Unsold Red Beets by Low-Temperature Enzyme-Assisted Extraction.

Food waste management plays a central role in the circular economy. To our knowledge, only a few studies have investigated the use of unsold fruit and vegetables from supermarkets as a substitute source for the extraction of natural colorants. Thus, the aim of this paper was to suggest a green, tailored protocol that avoids the use of organic solvents for the recovery of betalains from unsold red beets for use as a food colorant. The recovery of such pigments was carried out by a tailored enzymatic mix, blended considering the polysaccharide composition of the beetroot cell wall; thus, it consisted of: cellulase (37%), xylanase (35%), and pectinase (28%). The enzyme-assisted extraction protocol was optimized, and the most suitable conditions (in terms of pigment yield and color attributes) for the recovery of betalains from unsold beets appeared to be: 25 U/g total dose of enzymatic mix, temperature 25 °C, and processing time 240 min.

Release of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from milk protein isolate (MPI) during enzymatic hydrolysis.

The release of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from bovine milk protein isolate (MPI) during trypsin hydrolysis was studied using a design of experiments (DOE) approach. A 3 factor×3 level DOE including temperature (40, 50 and 60°C), enzyme to substrate ratio (E:S; 0.50, 1.25 and 2.00% (w/w)) and hydrolysis time (60, 150 and 240min) was used during the generation of 15 hydrolysates (H1-H15). The degree of hydrolysis (DH) varied between 6.98±0.31 (H8) to 12.75±0.62% (H10). The DPP-IV half maximal inhibitory concentration (IC50) ranged from 0.68±0.06 (H11)/0.68±0.10 (H4) to 1.59±0.11mgmL-1 (H8). Temperature had no effect (p>0.05) on the DPP-IV IC50 value, while an increase in E:S or time significantly decreased DPP-IV IC50 value (p<0.05). The DPP-IV IC50 value of 0.69mgmL-1, predicted by response surface methodology (RSM), to be obtained with an hydrolysate generated at 50.5°C, 2% ES and 231min (H16) was similar to the experimentally obtained value (DPP-IV IC50=0.66±0.10mgmL-1, p>0.05, n=3). Following simulated gastrointestinal digestion (SGID) of H16 (H16_CorPP), the DPP-IV IC50 value increased (p<0.05) to 0.90±0.07mgmL-1. There was no significant difference between the DPP-IV IC50 value of the SGID of MPI (MPI_CorPP, 0.89±0.11mgmL-1) and that of H16_CorPP. Potent known DPP-IV inhibitory peptide sequences were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) within H16, some of which were also present within H16_CorPP. MPI hydrolysates may be of interest for serum glucose regulation in humans.