Recent trends in methods used to obtain natural food colorants by freeze-drying

Innovative approaches to harnessing natural pigments from food waste and by-products for eco-friendly food coloring

With unprecedented growth in the world population, the demand for food has risen drastically leading to increased agricultural production. One promising avenue is recovery of value-added pigments from food waste which has been gaining global attention. This review focuses on sustainable strategies for extracting pigments, examining the factors that influence extraction, their applications, and consumer acceptability. The significant findings of the study state the efficiency of pigment extraction through innovative extraction techniques rather than following conventional methods that are time-consuming, and unsustainable. In addition to their vibrant colors, these pigments provide functional benefits such as antioxidant properties, extended shelf life and improved food quality. Societal acceptance of pigments derived from food waste is positively driven by environmental awareness and sustainability. The study concludes by highlighting the stability challenges associated with various natural pigments, emphasizing the need for tailored stabilization methods to ensure long-term stability and effective utilization in food matrices.

Advances in protein-based microcapsules and their applications: A review

Due to their excellent emulsification, biocompatibility, and biological activity, proteins are widely used as microcapsule wall materials for encapsulating drugs, natural bioactive substances, essential oils, probiotics, etc. In this review, we summarize the protein-based microcapsules, discussing the types of proteins utilized in microcapsule wall materials, the preparation process, and the main factors that influence their properties. Additionally, we conclude with examples of the vital role of protein-based microcapsules in advancing the food industry from primary processing to deep processing and their potential applications in the biomedical, chemical, and textile industries. However, the low stability and controllability of protein wall materials lead to degraded performance and quality of microcapsules. Protein complexes with polysaccharides or modifications to proteins are often used to improve the thermal instability, pH sensitivity, encapsulation efficiency and antioxidant capacity of microcapsules. In addition, factors such as wall material composition, wall material ratio, the ratio of core to wall material, pH, and preparation method all play critical roles in the preparation and performance of microcapsules. The application area and scope of protein-based microcapsules can be further expanded by optimizing the preparation process and studying the microcapsule release mechanism and control strategy.

Novel Efficient Physical Technologies for Enhancing Freeze Drying of Fruits and Vegetables: A Review

Drying is the main technical means of fruit and vegetable processing and storage; freeze drying is one of the best dehydration processes for fruit and vegetables, and the quality of the final product obtained is the highest. The process is carried out under vacuum and at low temperatures, which inhibits enzymatic activity and the growth and multiplication of micro-organisms, and better preserves the nutrient content and flavor of the product. Despite its many advantages, freeze drying consumes approximately four to ten times more energy than hot-air drying, and is more costly, so freeze drying can be assisted by means of highly efficient physical fields. This paper reviews the definition, principles and steps of freeze drying, and introduces the application mechanisms of several efficient physical fields such as ultrasonic, microwave, infrared radiation and pulsed electric fields, as well as the application of efficient physical fields in the freeze drying of fruits and vegetables. The application of high efficiency physical fields with freeze drying can improve drying kinetics, increase drying rates and maintain maximum product quality, providing benefits in terms of energy, time and cost. Efficient physical field and freeze drying technologies can be well linked to sustainable deep processing of fruit and vegetables and have a wide range of development prospects.

Heat Flux Analysis and Assessment of Drying Kinetics during Lyophilization of Fruits in a Pilot-Scale Freeze Dryer

Vacuum freeze-drying as a process for achieving high product quality has attracted increasing attention in the last decade. Particularly in the pharmaceutical field and food processing industries, lyophilization can produce high-quality products compared to samples dried by conventional methods. Despite its benefits, lyophilization is a time-consuming and costly process that requires optimization of a number of process parameters, including shelf temperature, chamber pressure, freezing rate, and process time. This paper reports on the implementation of heat flux measurements that allow noninvasive real-time determination of the endpoint of the primary drying stage as an essential parameter for the effective optimization of the overall drying time. Quantitative analysis of the drying kinetics of five fruits (kiwifruit, avocado, Asian pear, persimmon, and passion fruit) was assessed by comparing the heat flux and temperature profiles of samples during the lyophilization process. For a 24 h lyophilization cycle, average heat fluxes in the primary drying phase ranged from 250 to 570 W/m2. A significant correlation was found between the temperature and heat flux distributions at the estimated endpoint of the sublimation process and the corresponding transition into the secondary drying stage. Furthermore, good agreement was also found for the freezing phase. The use of real-time heat flux measurements proved to be a cost-effective experimental method to better understand the process variables in order to reduce the lyophilization cycle time and overall energy consumption.

A comprehensive review of recent development in extraction and encapsulation techniques of betalains

Betalains are attractive natural pigments with potent antioxidant activity, mainly extracted from the roots, tubers, leaves, flowers, and fruits of certain plants and some fungi. They constitute a reliable alternative to synthetic dyes used in the food industry and are considered toxic for consumers. In addition, there is convincing evidence of their health benefits for consumers. However, betalains are highly unstable to environment factors, such as light, heat, oxygen, water activity, and pH change which can be degraded during food processing, handling, storage, or delivery. Therefore, newly developed extraction methods and micro/nano-encapsulation techniques are currently applied to enhance the extraction yield, solve their instability problems, and improve their application in the food industry. This article aims to summarize the new advanced extraction methods of betalains, discussing the recent encapsulation techniques concerning the different encapsulating materials utilization. Betalains, natural pigments with potent antioxidant activity, are increasingly extracted from the roots, tubers, leaves, flowers, and fruits of certain plants and some fungi as safe alternatives to synthetic food dyes used in the food industry. However, their susceptibility to degradation during food processing, storage, and delivery poses challenges. Recent developments in extraction methods (e.g., supercritical fluid, pressurized liquid, ultrasound- and microwave-assisted, and enzyme-assisted) enhance betalain recovery, minimizing degradation. Encapsulation techniques using biopolymers, proteins, lipids, and nanoparticles protect betalains from environmental factors, extending shelf life and enabling controlled release. These advancements offer improved extraction efficiency, reduced solvent use, shorter processing times, and enhanced stability. Integration of these techniques in the food industry presents opportunities for incorporating betalains into various products, including functional foods, beverages, and dietary supplements. By addressing stability challenges, these developments support the production of innovative, healthier food items enriched with betalains. This article provides an overview of recent advancements in betalain extraction and encapsulation, highlighting their potential applications in the food industry.

Microencapsulation of anthocyanins as natural dye extracted from fruits - A systematic review

Anthocyanins are naturally colored compounds that can be extracted from plants, especially fruits. Their molecules are unstable under normal processing conditions; thus, they must be protected using modern technologies, such as microencapsulation. For this reason, many industries are searching for information from review studies to find the conditions that improve these natural pigments' stability. This systematic review aimed to elucidate different aspects of anthocyanins, such as main extraction and microencapsulation methods, gaps in analytical techniques, and industrial optimization measurements. Initially, 179 scientific articles were retrieved, of which seven clusters were found with 10-36 cross-linked references. Sixteen articles containing 15 different botanical specimens were included in the review, most focusing on the whole fruit, pulp, or subproducts. The extraction and microencapsulation technique resulting in the highest anthocyanin content was sonication with ethanol, temperature below 40 °C, and maximum time of 30 min, followed by microencapsulation by spray drying with maltodextrin or gum Arabic. Color apps and simulation programs may help verify natural dyes' composition, characteristics, and behavior.

Bioactive Compounds and Sensory Analysis of Freeze-Dried Prickly Pear Fruits from an Inter-Andean Valley in Peru

Prickly pear fruits are seasonal and have shades ranging from pale green to deep purple. Their pigments are associated with bioactive compounds, being sensitive to thermal transformation processes for their conservation. The objective of this research was to evaluate the bioactive compounds and the sensory analysis of freeze-dried prickly pear fruits from an inter-Andean valley in Peru. The prickly pear fruits of the morada, anaranjada, and blanca ecotypes came from an inter-Andean valley in Peru at 2972 m altitude. The sliced fruits were freeze-dried at -40 °C and 0.25 mTorr, and the total polyphenol content (TPC), vitamin C, and antioxidant activity (AA) were determined, as well as the color L* a* b*, color index (CI*), FTIR spectra, and mineral content. In the same way, sensory analysis of preferences with nine scales was applied. It was observed that in the freeze-dried fruits, TPC, AA, and vitamin C increased significantly (p-value < 0.05), and their corresponding functional groups increased in intensity in their corresponding FTIR spectra; furthermore, trace elements such as Cu, Fe, Se, Zn, Si, and Mn were identified. On the other hand, freeze-drying provided deeper colors to the fruits, which most panelists said they "very much liked" during the sensory analysis, although the texture was not very well accepted, with most panelists reporting being "indifferent" towards it. The freeze-drying technique allows the bioactive and sensory attributes of prickly pear fruits from inter-Andean valleys to be preserved, making it a potential fruit for export and conservation due to its seasonality.

Progress and Prospective of the Industrial Development and Applications of Eco-Friendly Colorants: An Insight into Environmental Impact and Sustainability Issues

Color is the prime feature directly associated with the consumer's attraction and choice of their food. The flavor, safety, and nutritional value of any food product are directly associated with the food color. Natural and synthetic colorants (dyes and pigments) have diversified applications in various sectors such as food, feed, pharmaceutical, textiles, cosmetics, and others. Concerning the food industry, different types of natural and synthetic colorants are available in the market. Synthetic food colorants have gained popularity as they are highly stable and cheaply available. Consumers worldwide prefer delightful foodstuffs but are more concerned about the safety of the food. After its disposal, the colloidal particles present in the synthetic colorants do not allow sunlight to penetrate aquatic bodies. This causes a foul smell and turbidity formation and gives a bad appearance. Furthermore, different studies carried out previously have presented the toxicological, carcinogenic effects, hypersensitivity reactions, and behavioral changes linked to the usage of synthetic colorants. Natural food colorings, however, have nutraceutical qualities that are valuable to human health such as curcumin extracted from turmeric and beta-carotene extracted from carrots. In addition, natural colorants have beneficial properties such as excellent antioxidant properties, antimutagenic, anti-inflammatory, antineoplastic, and antiarthritic effects. This review summarizes the sources of natural and synthetic colorants, their production rate, demand, extraction, and characterization of food colorants, their industrial applications, environmental impact, challenges in the sustainable utilization of natural colorants, and their prospects.

Sustainable Production of Pigments from Cyanobacteria

Pigments are intensely coloured compounds used in many industries to colour other materials. The demand for naturally synthesised pigments is increasing and their production can be incorporated into circular bioeconomy approaches. Natural pigments are produced by bacteria, cyanobacteria, microalgae, macroalgae, plants and animals. There is a huge unexplored biodiversity of prokaryotic cyanobacteria which are microscopic phototrophic microorganisms that have the ability to capture solar energy and CO2 and use it to synthesise a diverse range of sugars, lipids, amino acids and biochemicals including pigments. This makes them attractive for the sustainable production of a wide range of high-value products including industrial chemicals, pharmaceuticals, nutraceuticals and animal-feed supplements. The advantages of cyanobacteria production platforms include comparatively high growth rates, their ability to use freshwater, seawater or brackish water and the ability to cultivate them on non-arable land. The pigments derived from cyanobacteria and microalgae include chlorophylls, carotenoids and phycobiliproteins that have useful properties for advanced technical and commercial products. Development and optimisation of strain-specific pigment-based cultivation strategies support the development of economically feasible pigment biorefinery scenarios with enhanced pigment yields, quality and price. Thus, this chapter discusses the origin, properties, strain selection, production techniques and market opportunities of cyanobacterial pigments.

Sustainable Production and Characteristics of Dried Fermented Vegetables

The current fashion for healthy food and the increasing number of people with lactose intolerance make fermented vegetables increasingly important. On top of this, surpluses unused in the vegetable harvest can become a potential source of “green waste”. The use of fermentation and freeze-drying can result in a valuable, sustainable product that can solve the problems of spoiled vegetables and the need for refrigerated storage. Therefore, this study aimed to obtain sustainable dried fermented vegetables and to compare their selected physical and structural properties. Beetroot, carrot, and red pepper were selected for this purpose. These vegetables were subjected to a spontaneous lactic fermentation process. After the process, the vegetables were freeze-dried, and their structure and selected properties (color, dry weight, and the number of lactic acid bacteria) were determined. Fermented vegetables were found to differ from their raw sources in structure and color, the main discrepancies being shown by the b* factor (yellow-blue). Root vegetables had smaller pores of structure in the freeze-dried samples than red peppers. The freeze-drying process did not affect the number of bacteria. It can be concluded that both the fermentation and the freeze-drying processes affected the structure of the selected vegetables. All tested vegetables can be fermented and freeze-dried without major changes in color and microbiological properties and can be used as a potential source of lactic acid bacteria and health-promoting pigments, e.g., in the form of chips. In addition, their shelf life is extended.

Preparation of sulphuric acid-mediated N,S-codoped red emissive carbon dots: Applications in food dyes detection, solid-state luminescence and cell imaging

As diseases such as cardiovascular disease and cancer caused by food problems are more and more frequent, food safety has received great attention. Among them, the safety problem caused by food dyes is more prominent. Thus, it is of great value to develop sensitive detection methods for food dyes. In present study, sulphuric acid-mediated N,S-codoped red emissive carbon dots (namely as R-CDs) had been manufactured by using N-phenyl-o-phenylenediamine as precursor, sulfuric acid as additive for the first time. The structural and fluorescence properties of R-CDs had been systematically studied. The results demonstrated that R-CDs showed uniform spherical morphology and had a graphite-like structure, for which the average diameters size was 5.05 nm. Due to the various functional groups such as hydroxyl, pyridinic N, pyrrolic N and -C-SO₄, R-CDs emitted bright red fluorescence. Importantly, because of the interactions between the functional groups of R-CDs with the selected food dyes, three dyes including amaranth, brilliant blue FCF and methylene blue can sensitively quench the fluorescence of R-CDs through IFE and static quenching effects. The linearity ranges of them were separately detected as 0.20 μM -20 μM, 10 nM-1 μM and 60 nM-8 μM. The limits of detection (LODs) of them were 70 nM, 4 nM and 20 nM, respectively. Further, R-CDs was successfully applied to the sensitive detection of three dyes from various food samples. To maximize the fluorescence properties of R-CDs, a R-CDs/PVA composite gel was fabricated to make R-CDs fluoresce in solid state condition. The potential of R-CDs/PVA composite gel for preliminary visualization analysis of three dyes was studied. Finally, ascribed to the low toxicity and good biocompatibility, the potential of R-CDs as probe for cell imaging was explored preliminarily.

Polysaccharide-based porous biopolymers for enhanced bioaccessibility and bioavailability of bioactive food compounds: Challenges, advances, and opportunities

Bioactive food compounds, such as lycopene, curcumin, phytosterols, and resveratrol, have received great attention due to their potential health benefits. However, these bioactive compounds (BCs) have poor chemical stability during processing and low bioavailability after consumption. Several delivery systems have been proposed for enhancing their stability and bioavailability. Among these methods, porous biopolymers have emerged as alternative encapsulation materials, as they have superior properties like high surface area, porosity, and tunable surface chemistry to entrap BCs. This reduces the crystallinity (especially for the lipophilic ones) and particle size, and in turn, increases solubilization and bioavailability. Also, loading BCs into the porous matrix can protect them against environmental stresses such as light, heat, oxygen, and pH. This review introduces polysaccharide-based porous biopolymers for improving the bioaccessibility/bioavailability of bioactive food compounds and discusses their recent applications in the food industry. First, bioaccessibility and bioavailability are described with a special emphasis on the factors affecting them. Then, porous biopolymer fabrication methods, including supercritical carbon dioxide (SC-CO₂ ) drying, freeze-drying, and electrospinning and electrospraying, are thoroughly discussed. Finally, common polysaccharide-based biopolymers (i.e., starch, nanocellulose, alginate, and pectin) used for generating porous materials are reviewed, and their current and potential future food applications are critically discussed.

Nature's palette: An emerging frontier for coloring dairy products

Consumers all across the world are looking for the most delectable and appealing foods, while also demanding products that are safer, more nutritious, and healthier. Substitution of synthetic colorants with natural colorants has piqued consumer and market interest in recent years. Due to increasing demand, extensive research has been conducted to find natural and safe food additives, such as natural pigments, that may have health benefits. Natural colorants are made up of a variety of pigments, many of which have significant biological potential. Because of the promising health advantages, natural colorants are gaining immense interest in the dairy industry. This review goes over the use of various natural colorants in dairy products which can provide desirable color as well as positive health impacts. The purpose of this review is to provide an in-depth look into the field of food (natural or synthetic) colorants applied in dairy products as well as their potential health benefits, safety, general trends, and future prospects  in food science and technology. In this paper, we listed a plethora of applications of natural colorants in various milk-based products.

Aralia cordata Thunb. as a Source of Bioactive Compounds: Phytochemical Composition and Antioxidant Activity

Plant primary and secondary metabolites are a significant source for many applications, including extractions of functional components, green synthesis development, and producing higher-added value products. However, in the variety of botanicals, Aralia cordata Thunb. plant is getting attention for its similarity to ginseng. This study comprehensively examines the biochemical and phytochemical profiles of different A. cordata morphological parts: root, stem, leaf, inflorescence, berry, and seed. Additionally, the establishment of total phenolic content and quantitative analysis of powerful antioxidants such as chlorophyll, carotenoids (zeaxanthin, lutein, and β-carotene), proanthocyanidins, and anthocyanins content were evaluated. The results indicated that A. cordata stem and berries are an excellent source of anthocyanins in the range from 18.27 to 78.54 mg/100 g DW. Meanwhile, the antioxidant activity was evaluated using three different methods based on the capacity to scavenge: DPPH^• scavenging capacity, ABTS^•+ radical cation assay, and ferric reducing antioxidant power (FRAP) and ranged from 27 to 168 µmol TE/g DW, 8 to 117 µmol TE/g DW, and 18 to 157 µmol TE/g DW, respectively. This study proposes a novel competitive plant for many health-promoting applications in the nutraceutical, pharmaceutical, material, and food industries.

Effects of electrostatic spray drying on the sensory qualities, aroma profile and microstructural features of instant Pu-erh tea

The sensory qualities, aroma profile, and microstructural features of instant Pu-erh teas (IPTs) produced by electrostatic spray drying (ESD) were evaluated by sensory and instrumental analyses and compared with those produced by other drying methods (freeze-drying [FD], vacuum drying [VD], and conventional spray drying [CSD]). The sensory qualities of ESDIPT were similar to those of FDIPT, and better than those of VDIPT and CSDIPT. Eighty-eight volatiles were detected in all IPTs, and 45 odor-active compounds were captured. Most of their OAVs were higher in ESDIPT than in VDIPT and CSDIPT but were lower than those in FDIPT. Dihydro-β-ionone had the highest OAV. Aroma recombination experiments were performed to verify the identification results. ESDIPT was present in the shape of microspheres with many regular concave surfaces, which was different from those treated by other drying methods. In terms of sensory quality and productivity, ESD would be a potential method for IPT production.

Effect of lyophilized chive (Allium wakegi Araki) supplementation to the frying batter mixture on quality attributes of fried chicken breast and tenderloin

Batter mixtures for frying chicken breasts and tenderloins were supplemented with different amounts (0, 3, 5, and 7%) of lyophilized chives (Allium wakegi Araki). The viscosity of the batter mixture, crispness of the fried batter, fat and ash contents, caloric value, coating pickup, and frying yield were directly proportional, whereas the lightness, redness, yellowness, and pH were inversely proportional, to the amount of lyophilized chives in the batter. Principal component analysis revealed that the aromatic profiles varied between the 0%, 3%, and 5% lyophilized chive-supplemented groups in both the breast and tenderloin samples. However, the aromatic profiles of the 7% and 5% lyophilized chive-supplemented samples were similar. The taste profile of the 7% lyophilized chive-supplemented sample was different from those of the 0%, 3%, or 5% lyophilized chive-supplemented samples. The sensory characteristics of the 5% lyophilized chive-supplemented breast samples and 3% or 5% lyophilized chive-supplemented tenderloin samples received the best scores by sensory panelists.

Emerging drying techniques for food safety and quality: A review

The new trends in drying technology seek a promising alternative to synthetic preservatives to improve the shelf-life and storage stability of food products. On the other hand, the drying process can result in deformation and degradation of phytoconstituents due to their thermal sensitivity. The main purpose of this review is to give a general overview of common drying techniques with special attention to food industrial applications, focusing on recent advances to maintain the features of the active phytoconstituents and nutrients, and improve their release and storage stability. Furthermore, a drying technique that extends the shelf-life of food products by reducing trapped water, will negatively affect the spoilage of microorganisms and enzymes that are responsible for undesired chemical composition changes, but can protect beneficial microorganisms like probiotics. This paper also explores recent efficient improvements in drying technologies that produce high-quality and low-cost final products compared to conventional methods. However, despite the recent advances in drying technologies, hybrid drying (a combination of different drying techniques) and spray drying (drying with the help of encapsulation methods) are still promising techniques in food industries. In conclusion, spray drying encapsulation can improve the morphology and texture of dry materials, preserve natural components for a long time, and increase storage times (shelf-life). Optimizing a drying technique and using a suitable drying agent should also be a promising solution to preserve probiotic bacteria and antimicrobial compounds.

Study on changes in pigment composition during the blooming period of safflower based on plant metabolomics and semi-quantitative analysis

Red and yellow pigments are the major ingredients of safflower, often used to color food and cosmetics. Carthamin was the main component of red pigment and hydroxysafflor yellow A and anhydrosafflower yellow B were representative components of yellow pigment. Plant metabolomics and semi-quantitative analysis were used to analyze the changes of pigment composition during the blooming period, especially these characteristic components. Carthamin, hydroxysafflor yellow A, anhydrosafflower yellow B, and other components were screened out as differential metabolites based on plant metabolomics. Then semi-quantitative analysis was used to quantify these three representative components of pigments. Experimental results showed that the content of pigments has dynamic changes along with flowering, in the early blooming period, yellow pigment accumulated much and red pigment was low in content. In the middle period, the accumulation rate of the yellow pigment slowed down and content was stabilized. In the next step, the content of yellow pigments gradually decreased, and the content of red pigments gradually increased. Later, the level of yellow pigment decreased significantly, and the accumulation rate of red pigment increased significantly. Last, the appearance color of safflower was red, with yellow parts barely visible, and accumulation of red pigment was the highest and of the yellow pigment was the lowest in content.

Study on the Potential Application of Impatiens balsamina L. Flowers Extract as a Natural Colouring Ingredient in a Pastry Product

Flowers of the genus Impatiens are classified as edible; however, their inclusion in the human diet is not yet a common practice. Its attractive colours have stirred great interest by the food industry. In this sense, rose (BP) and orange (BO) I. balsamina flowers were nutritionally studied, followed by an in-depth chemical study profile. The non-anthocyanin and anthocyanin profiles of extracts of both flower varieties were also determined by high-performance liquid chromatography coupled to a diode array and mass spectrometry detector (HPLC-DAD-ESI/MS). The results demonstrated that both varieties presented significant amounts of phenolic compounds, having identified nine non-anthocyanin compounds and 14 anthocyanin compounds. BP extract stood out in its bioactive properties (antioxidant and antimicrobial potential) and was selected for incorporation in "bombocas" filling. Its performance as a colouring ingredient was compared with the control formulations (white filling) and with E163 (anthocyanins) colorant. The incorporation of the natural ingredient did not cause changes in the chemical and nutritional composition of the product; and although the colour conferred was lighter than presented by the formulation with E163 (suggesting a more natural aspect), the higher antioxidant activity could meet the expectations of the current high-demand consumer.

Influence of Drying Type of Selected Fermented Vegetables Pomace on the Natural Colorants and Concentration of Lactic Acid Bacteria

Nowadays, foods with probiotic bacteria are valuable and desired, because of their influence on human gut and health. Currently, in the era of zero waste, the food industry is interested in managing its waste. Therefore, the aim of the study was to determine the influence of drying process on the physicochemical properties of fermented vegetable pomace. The work included examining the influence of the lactic acid bacteria (Levilactobacillus brevis, Lactiplantibacillus plantarum, Limosilactobacillus fermentum and its mixture in the ratio 1:1:1) used for vegetable fermentation (beetroot, red pepper, carrot), obtaining pomace from fermented vegetables, and then selection of drying technique using the following methods: convection drying (CD) or freeze-drying (FD) on the physical and chemical properties of pomace. In the obtained pomace and its dried form, dry substance, water activity, color, and active substances such as betalains and carotenoids by spectrophotometric method and also bacteria concentration were evaluated. After fermentation of pomace from the same vegetable, a similar concentration of lactic acid bacteria was found as well as dry substances, color and colorants. Results of physico-chemical properties were related to the used vegetable type. After drying of pomace, it could be seen a high decrease in bacteria and colorant concentration (betalains, carotenoids) independently from drying and vegetable type as well as used starter cultures. The smallest change was observed for spontaneously fermented vegetables compared to those in which the starter culture was used.

Effect of nonthermal treatments on selected natural food pigments and color changes in plant material

In recent years, traditional high-temperature food processing is continuously being replaced by nonthermal processes. Nonthermal processes have a positive effect on food quality, including color and maintaining natural food pigments. Thus, this article describes the influence of nonthermal, new, and traditional treatments on natural food pigments and color changes in plant materials. Characteristics of natural pigments, such as anthocyanins, betalains, carotenoids, chlorophylls, and so forth available in the plant tissue, are shortly presented. Also, the characteristics and mechanism of nonthermal processes such as pulsed electric field, ultrasound, high hydrostatic pressure, pulsed light, cold plasma, supercritical fluid extraction, and lactic acid fermentation are described. Furthermore, the disadvantages of these processes are mentioned. Each treatment is evaluated in terms of its effects on all types of natural food pigments, and the possible applications are discussed. Analysis of the latest literature showed that the use of nonthermal technologies resulted in better preservation of pigments contained in the plant tissue and improved yield of extraction. However, it is important to select the appropriate processing parameters and to optimize this process in relation to a specific type of raw material.

The Influence of Different Pretreatment Methods on Color and Pigment Change in Beetroot Products

Vegetable processing pomace contains valuable substances such as natural colors that can be reused as functional ingredients. Due to a large amount of water, they are an unstable material. The aim of our research was to assess how the pretreatment method (thermal or nonthermal) affects the properties of powders obtained from beet juice and pomace after the freeze-drying process. The raw material was steamed or sonicated for 10 or 15 min, and then squeezed into juice and pomace. Both squeezed products were freeze-dried. The content of dry substance; L*, a*, and b* color parameters; and the content of betalain pigments were analyzed. Pretreatments increased the proportion of red and yellow in the juices. Steam and ultrasound caused a significant reduction in parameter b* in the dried pomace. A significant increase in betanin in lyophilizates was observed after pretreatment with ultrasound and steam for 15 min. As a result of all experiments, dried juices and pomaces can also be used as a colorant source. However, there is higher potential with pomaces due to their additional internal substances as well as better storage properties. After a few hours, juice was sticky and not ready to use.

Effects of lyophilized black mulberry water extract on lipid oxidation, metmyoglobin formation, color stability, microbial quality and sensory properties of beef patties stored under aerobic and vacuum packaging conditions

The objective was to determine the effects of different concentrations of lyophilized black mulberry water extract (BMWE) on lipid oxidation, metmyoglobin (MMb) formation, color stability, microbial quality, and sensory properties of aerobic (AP) and vacuum (VP) packaged beef patties during 15 days of chilled storage. Compared to control, incorporating of BMWE decreased (P < .01) the pH, thiobarbituric acid reactive substances (TBARS), MMb, and hue angle values of both AP and VP beef patties, while improving the redness (a*) and chroma values (P < .01). Addition of BMWE contributed significantly to extending the shelf life of beef patties by limiting lipid oxidation, discoloration and microbial growth during storage compared to control (P < .01). Although the lowest TAMB (total aerobic mesophylic bacteria) counts, TBARS and MMb values were determined in 0.4% BMWE groups, 0.2% BMWE was the most favourable concentration considering sensory acceptability and instrumental redness. These results showed that BMWE could be used as a promising natural colorant, antioxidant and antimicrobial agent in beef patties instead of synthetic additives.

The Quality of Red Bell Pepper Subjected to Freeze-Drying Preceded by Traditional and Novel Pretreatment

It has been demonstrated previously in the literature that utilization of PEF or a combination of a pulsed electric field (PEF) and ultrasounds (US) can facilitate dehydration processes and improve the quality of dried products even better than the application of thermal methods such as blanching. The aim of the study was to evaluate the quality of red bell pepper subjected to freeze-drying preceded by blanching or PEF or US treatment applied in a single and combined mode. Furthermore, the freeze-drying was preceded by shock freezing or vacuum freezing performed inside the freeze-dryer as a result of pressure drop during the first stage of freeze-drying. All of the analyzed technological variants enhanced the drying kinetics when compared to the intact material. Freeze-dried bell pepper subjected to non-thermal pretreatment exhibited higher vitamin C, total phenolic and carotenoids content than blanched material despite the fact that blanching reduced drying time the most compared to all other analyzed methods.

Spectroscopic, mineral, and antioxidant characteristics of blue colored powders prepared from cornflower aqueous extracts

The present study aimed to prepare blue colored powders from an aqueous extract of cornflower petals. Low temperature (4 °C) aqueous extraction (1:20) and microencapsulation by freeze-drying were performed. A mixture of stabilizers (maltodextrin, guar gum, and lecithin) in a proportion of 10% to the amount of extract was used. The results indicated that the addition of 2% and 4% guar gum to maltodextrin (8-6%) significantly increased the efficiency of the process, but 4% guar gum caused the formation of amorphous particles; therefore, 2% guar gum addition was found to be the most optimal. The FT-IR and FT-Raman band characteristics for guar gum, lecithin, and maltodextrin dominated over those for anthocyanins contained in the powders made from cornflower petals. The blue powders had total phenolic content of 19.5-26.6 mg GAE/g DW. The antioxidant activity of the prepared powders measured by ABTS, CHEL, OH, and RED was high.

Recent Trends in Pretreatment of Food before Freeze-Drying

Drying is among the most important processes and the most energy-consuming techniques in the food industry. Dried food has many applications and extended shelf life. Unlike the majority of conventional drying methods, lyophilization, also known as freeze-drying (FD), involves freezing the food, usually under low pressure, and removing water by ice sublimation. Freeze-dried materials are especially recommended for the production of spices, coffee, dried snacks from fruits and vegetables and food for military or space shuttles, as well as for the preparation of food powders and microencapsulation of food ingredients. Although the FD process allows obtaining dried products of the highest quality, it is very energy- and time consuming. Thus, different methods of pretreatment are used for not only accelerating the drying process but also retaining the physical properties and bioactive compounds in the lyophilized food. This article reviews the influence of various pretreatment methods such as size reduction, blanching, osmotic dehydration and application of pulsed electric field, high hydrostatic pressure or ultrasound on the physicochemical properties of freeze-dried food and drying rate.

Tailoring the Functional Potential of Red Beet Purées by Inoculation with Lactic Acid Bacteria and Drying

This study was focused on a comparative analysis of two drying methods, such as convective and infrared drying, on the red beetroot purées with lactic acid bacteria, as a strategy for tailoring the health benefits of the selected plant. For both varieties, the total betalain contents varied from 13.95 ± 0.14 mg/g dry weight in Beta vulgaris var. cylindra when compared with 11.09 ± 0.03 mg/g dry weight in Beta vulgaris var. vulgaris, whereas significant differences were found in total phenolic and flavonoid contents. Significant drying induced changes were found in selected bioactives, in terms of total betalains, flavonoids, and polyphenols, which influenced the antioxidant activities of the purées, structure, and color parameters. In general, infrared technology was more protective, leading to an increase of 20% in flavonoids content. One logarithmic decrease in cell viability was observed in all powders samples. After the in vitro digestion, the betalains decreased, in both gastric and intestinal simulated juices, with a more pronounced profile in infrared processed purées. Textural and rheological analysis of the dried purées highlighted that the infrared drying is milder compared to the conventional one, allowing us to obtain powders with enhanced functional properties, in terms of bioactives content, cell viability, color, and structural and rheological behavior.

Effect of Carrier Agents on the Physicochemical and Technofunctional Properties and Antioxidant Capacity of Freeze-Dried Pomegranate Juice (Punica granatum) Powder

The physicochemical and technofunctional properties and antioxidant capacity of freeze-dried "Wonderful" pomegranate juice powder (PJP), produced with different carrier agents, were investigated. Powders were produced using maltodextrin, gum Arabic, and waxy starch as carrier agents and characterised by scanning electron microscopy (SEM) and particle size distribution. Results showed that PJP produced with maltodextrin had the highest yield (46.6%), followed by gum arabic (40.6%), while waxy starch had the least yield (35.4%). Powders produced with maltodextrin (96.5%) and gum arabic (96.1%) were highly soluble, which indicates better reconstitution properties. Waxy starch-added PJP had the lowest hygroscopicity (4.7%), which offers good stability during storage and a lower degree of caking compared to maltodextrin (10.2%) and gum arabic (12.6%) powders. Powders obtained from maltodextrin and gum arabic exhibited larger particle diameters ranging between 12 to 120 µm while the lowest particle diameter range was with powders formed from waxy starch (8-40 µm). Freeze-dried pomegranate powder produced with maltodextrin retained more redness (a*) by approximately 44%, compared to gum arabic. Similarly, PJP with maltodextrin and gum arabic had higher total soluble solids (10.3 and 10.4 °Brix), respectively. Total anthocyanin content was 54% more in PJP with maltodextrin than waxy starch PJP. Similarly, the powder produced with maltodextrin had higher radical scavenging activity (33.19 mM TE/g dry matter; DM) compared to gum arabic (28.45 mM TE/g DM) and waxy starch (26.96 mM TE/g DM). Overall, maltodextrin reflected the most suitable carrier agent to produce PJP.