Clarification of pomegranate juice with chitosan: Changes on quality characteristics during storage

Harnessing the Potential of Chitosan and Its Derivatives for Enhanced Functionalities in Food Applications

As one of the most abundant natural polysaccharides that possess good biological activity, chitosan is extracted from chitin. Its application in the food field is being increasingly valued. However, chitosan extraction is difficult, and its poor solubility limits its application. At present, the extraction methods include the acid-base method, new chemical methods, and biological methods. The extraction rates of chitin/chitosan are 4-55%, 13-14%, and 15-28%, respectively. Different chemical modifications have different effects on chitosan, making it applicable in different fields. This article reviews and compares the extraction and chemical modification methods of chitosan, emphasizing the importance of green extraction methods. Finally, the application prospects of chitosan in the food industry are discussed. This will promote the understanding of the advantages and disadvantages of different extraction methods for chitosan as well as the relationship between modification and application, providing valuable insights for the future development of chitosan.

Application of natural fining agents to clarify fruit juices

The consumption of fruit juices has been increasingly growing all over the world. The clarification process is considered as one of the most important stages in fruit juice production, which can provide the products with desired clear visual appearance. Nowadays, the tendency of consumers to use the natural-clarified fruit juices encourages the researchers to allocate much attention on utilization of natural clarifying agents to clarify different fruit juices. This review article has first introduced the most frequent causes of turbidity in fruit juices including polysaccharides (i.e., cellulose, hemicelluloses, lignin, starch, and pectic substances), proteins and polyphenols (especially tannins) as well as their removal mechanisms. After that, a comprehensive summary of research on natural fining agents, including clay minerals, polysaccharides, proteins, enzymes (free and immobilized forms), and activated carbon is provided with a focus on their application in the juice clarification process. The chemical composition of natural substances, their efficiency on reduction of turbidity-causing compounds and the changes in properties of clarified juices such as turbidity (clarity), total phenolic content, total anthocyanins, viscosity, and sensory evaluation followed by their stability during the storage have been deeply discussed.

Effects and impacts of technical processing units on the nutrients and functional components of fruit and vegetable juice

Fruit and vegetable juice (FVJ) has become a favorite beverage for all age groups because of its excellent sensory and nutritional qualities. FVJ has a series of health benefits such as antioxidant, anti-obesity, anti-inflammatory, anti-microbial and anti-cancer. Except for raw materials selection, processing technology and packaging and storage also play a vital role in the nutrition and functional components of FVJ. This review systematically reviews the important research results on the relationship between FVJ processing and its nutrition and function in the past 10 years. Based on the brief elucidation of the nutrition and health benefits of FVJ and the unit operation involved in the production process, the influence of a series of key technology units, including pretreatment, clarification, homogenization, concentration, sterilization, drying, fermentation and packaging and storage, on the nutritional function of FVJ was systematically expounded. This contribution provides an update on the impacts of technical processing units on the nutrients and functional components of FVJ and new perspectives for future studies.

Comparison of the Degree of Acetylation of Chitin Nanocrystals Measured by Various Analysis Methods

Chitin and its derivate chitosan have versatile properties and have been used in various applications. One key parameter determining the functionality of chitin-based materials is the degree of acetylation (DA). For DA determination, NMR and FTIR spectroscopy are often considered to be the gold standard, but these techniques may not always be available and are rather time-consuming and costly. The first derivative UV method has been suggested, although accurate measurements can be challenging for materials with high degrees of acetylation, due to hydroxymethylfurfural (HMF) formation and other side reactions occurring. In this paper, we re-evaluated the first derivate UV method for chitin and chitosan powder, chitin nanocrystals, and deacetylated chitin nanocrystals. Our results showed that the first derivative UV method is capable of measuring DA with high accuracy (>0.9), leading to values comparable to those obtained by 1H NMR, 13C NMR, and FTIR. Moreover, by-product formation could either be suppressed by selecting the proper experimental conditions, or be compensated. For chitin nanocrystals, DA calculation deviations up to 20% due to by-product formation can be avoided with the correction that we propose. We conclude that the first derivative UV method is an accessible method for DA quantification, provided that sample solubility is warranted.

Contribution of polysaccharides from crustacean in fermented food products

Fermented foods are of great importance for their role in preserving nutrients and enriching the human diet. Fermentation ensures longer shelf life and microbiological safety of food. Natural bioactive compounds have been paid attention as nutraceuticals or functional ingredients, which have health-promoting components since polysaccharides, especially chitosan, chitin and their derivatives, are biocompatible and biodegradable, biorenewable, without toxic properties and environmentally friendly. They have been applied in several fields such as medicine, agriculture, and food industry. This chapter provides information on polysaccharides obtained from crustacean as bioactive compounds as well as their effects in fermented foods.

Optimized Clarification Technology of Bayberry Juice by Chitosan/Sodium Alginate and Changes in Quality Characteristics during Clarification

In this study, a novel method to clarify bayberry juice with composite clarifiers, chitosan and sodium alginate, has been designed. The optimal conditions were as follows: using chitosan 0.05 g/L first and then sodium alginate 0.05 g/L as composite clarifiers, standing for 2 h at 25 °C. The transmittance increased from 0.08 to 91.2% after treating by composite clarifiers, which was significantly higher than using chitosan (44.29%) and sodium alginate (38.46%) alone. It was also found that sedimentation time of juice treated by composite clarifiers was about 60% shorter than using single clarifiers. Meanwhile, the reduction of anthocyanin in juice was 9.16% for composite clarifiers treatment, being less than that for the single sodium alginate and previous related researches. In addition, the color and aroma of bayberry juice treated by composite clarifiers were improved. Juice treated by composite clarifiers had the highest L* value with 52.48 and looked more attractive. The present research revealed that content of beta-damascenone and dihydro-5-pentyl-2(3H)-furanone increased after treatment with composite clarifiers which contributed more to the pleasant aroma. Overall, the developed method improved the clarification effect and sensory quality, and reduced the sedimentation time, which may be promising in the production of clear bayberry juice.

One pot clarification and debittering of grapefruit juice using co-immobilized enzymes@chitosanMNPs

In the present work, enzymes pectinase and naringinase were simultaneously co-immobilized on an eco-friendly chitosan coated magnetic nanoparticles (chitosanMNPs) by cross-linking using chitosan as a macro-molecular cross-linker. The maximum activity recovery of both enzymes in the co-immobilized form was obtained at chitosanMNPs to enzymes ratio of 1:3, 3% cross-linker concentration and 150 min cross-linking time. The synthesized MNPs before and after co-immobilization were characterized using different techniques. The prepared biocatalyst was found spherical with an average size below 200 nm and showed supermagnetic property with saturation magnetization of 38.28 emu/g. The optimum pH and temperature of both enzymes in co-immobilized form was found at 5.5 and 65 °C. The prepared biocatalyst exhibited an improved thermal stability with 1.8-fold increase in the half-life. The secondary structural analysis revealed that, prepared co-immobilized biocatalyst undergone changes in the conformational and structural rigidity due to macro-molecular cross-linker. The co-immobilized biocatalysts were evaluated for one pot clarification and debittering of grapefruit juice and found ~52% reduction in turbidity and ~85% reduction in the naringin content. The co-immobilized enzymes were recycled up to 7^th cycle and can be easily stored at room temperature for 30 days retaining up to 64% and 86% residual activities respectively.

Effect of extract or infusion of leaves of the Hibiscus sabdariffa L. in the production and storage of the beverage blends with cupuassu: physico-chemical and sensory acceptance

This study aimed to produce beverages using extract or infusion of Hibiscus sabdariffa leaves with cupuassu pulp. The blended drinks with cold or hot extraction were formulated using the response surface methodology. Moreover, the physico-chemical and sensory stability of these beverages was performed for 180 days. The conditions production for beverage leaf extract were: 28% leaf extract, 72% cupuassu pulp, and 14°Brix. For beverage leaf infusion, were 37% leaf extract, 63% cupuassu pulp, and 13°Brix. Comparing the two beverages, the polyphenolic compounds and the antioxidant activity (ABTS and DPPH) were higher in the blends produced with leaf extract. Thus, the cold extract provided better extraction of these components in the leaves. During storage, pH, reducing and total sugars and soluble solids of blends increased linearly (p < 0.05). Nevertheless, vitamin C, polyphenolic compounds, and the antioxidant activity reduced linearly (p < 0.05). The sensory acceptance of blends containing leaf extract, in the hedonic scale, all sensory attributes were positively scored up to 135 days. At 180 days, the acceptance reduced for rejection. The blended beverage containing leaf infusion had all sensory attributes positively scored up to 90 days, with a rating between 6.27 and 7.42. At 135 and 180 days, the values were in the indifference region of the hedonic scale or acceptance region. Therefore, the blend with leaf infusion maintained better acceptance during storage when compared to leaf extract beverage. Thus, the blended beverages had good nutritional value and sensory acceptance and were acceptable for up to 135 days.

Improving the qualitative indicators of apple juice by Chitosan and ultrasound

Today's consumers desire for tasty, nutritious, and safe food products, so researchers are looking for new ways in which little heat or no heat at all is used for processing. This study was to evaluate the effect of treatment using an ultrasonic bath (for 15, 30, and 60 min at 40 and 60°C) and ultrasonic probe (for 10, 15, and 20 min at 40 and 60°C), treatment with Chitosan, and combination of them on the quality of apple juice that includes physicochemical features (pH, acidity, total solid matter), total polyphenol, total antioxidant capacity, the cloud point, and color values of Hunter (L*, a*, b*) in the treated samples and comparing them with each other. The results showed that ultrasound has no effect on the pH and acidity, while the total solid of ultrasound treatment was higher than controls in combination with Chitosan (p < 0.05). Total polyphenols of apple juice samples treated by ultrasonic probe are higher than an ultrasonic bath (p < 0.05). The total antioxidant capacity has improved in treatments (p < 0.05). According to the results there is a significant difference between the cloud point of control samples and Chitosan (p < 0.05). The L* (brightness) increased in ultrasonic probe method and had a significant decline in Chitosantreatment (p < 0.05). Findings from this study suggest that the use of ultrasound treatment in the production of apple juice can improve quality factors, and in this regard, ultrasonic probe is more effective.

Ultrasound-assisted extraction of bioactive compounds from green tea leaves and clarification with natural coagulants (chitosan and Moringa oleífera seeds)

In this study, a sequential process of extraction and clarification by natural coagulants and centrifugation successfully produced green tea extracts clear and enriched in bioactive compounds. Desirability function methodology was applied to optimize ultrasound-assisted extraction (UAE) of total polyphenols and flavonoids by the evaluation of the parameters temperature (22-83 °C), tea-to-water ratio (12-73 g  L^-1) and amplitude (23-77%). Green tea clarification was carried out using the extract at UAE optimized conditions (77, 73 g L^-1, 77%). The effect of centrifugation and the concentrations of chitosan (25-2000 mg L^-1) and Moringa oleífera seeds (MOS) (100-10000 mg L^-1) were evaluated. The best clarification conditions were at the concentrations of chitosan 500 mg L^-1 and MOS 8000 mg L^-1 followed by centrifugation. These optimized clarification conditions provided turbidity, solids and polyphenols reduction of 95% and 96%, 16 and 16%, 18 and 19% for chitosan and MOS treatments, respectively. The main individual compounds identified by high liquid chromatography (HPLC) were epigallocatechin gallate, epicatechin, epigallocatechin and catechin, gallic acid and caffeine.

Alterations on phenolic compounds and antioxidant activity during sour grape juice concentrate processing

The alterations of phenolic compounds and antioxidant capacity of sour grape juice were investigated during the concentration process stages. Phenolics and antioxidant properties of the samples changed more at the vacuum evaporation stage than that of the other stages. After evaporation, the antioxidant capacity of the samples decreased approximately between 14.2 and 17.0 % for DPPH and ABTS methods, respectively. Besides, phenolic contents also decreased approximately as 14.8%. HPLC data on phenolics of sour grape juice during concentrate processing gave 12 polyphenols, including gallic acid, (+)-catechin, (-)-epigallocatechin, vanillic acid, (-)-epigallocatechin gallate, (-)-epicatechin, caftaric acid, caffeic acid and p-coumaric acid, which were determined as 1.05-1.83 mg/100 g, 5.40-7.83 mg/100 g, 6.35-9.21 mg/100 g, 3.01-5.18 mg/100 g, 0- 1.95 mg/100 g, 2.33-3.54 mg/100 g, 12.40-37.60 mg/100 g, 1.44-2.26 mg/100 g and 0.27-0.44 mg/100 g, respectively. Ferulic, sinapic acids and quercetin were only detected at concentrate step of the sour grape juice processing and were found as 0.18 mg/100 g, 0.28 mg/100 g and 0.76 mg/100 g, respectively.

Effect of enzymatic treatment on the rheological behavior and vitamin C content of Spondias tuberosa (umbu) pulp

Umbu is a native fruit of the semi-arid Northeastern region of Brazil, which presents an exotic and differentiated flavor. Containing vitamin C and presenting a high potential of consumption, no appropriated technology has been developed to process this fruit and expand its commercialization to other markets. The enzymatic treatment of fruit pulps leads to viscosity reduction, which makes possible an efficient processing for obtaining high quality umbu juices. In order to contribute to the valorization of this underexploited culture, two commercial pectinolytic enzymes, Pectinex Ultra SP-L^® and Rapidase TF^®, were used to promote viscosity reduction of umbu pulp. The effect of reaction temperature (35, 45 and 55 °C) and enzyme concentration (100, 200 and 300 ppm) on the rheological properties of the fruit pulp was evaluated. In relation to the viscosity of the original pulp (84.8 mPa s at 100 s^-1 shear rate), a significant, four times lower, viscosity reduction of 18.9 mPa s was observed. Under optimum process condition (35 °C and Rapidase at 100 ppm concentration), the lowest viscosity was achieved after 40 min of reaction. Under these reaction conditions, no significant change was found in the vitamin C content, indicating the preservation of functional and nutritional properties of umbu pulp.

Optimization of process parameters for enhanced production of Jamun juice using Pectinase (Aspergillus aculeatus) enzyme and its characterization

Jamun fruit comprises of seed and thick pulp. The pectin-protein bond of the thick pulp creates difficulty in making juice. Clear Jamun juice is not available in the market, so there is a need for extraction of juice with maximum yield. The goal of this research is to obtain high yield of clarified juice with the help of Pectinase (Aspergillus aculeatus) enzyme. The study was conducted at different enzyme concentration (0.01-0.1%), time duration (40-120 min), and temperature (30-50 °C). Various physical and chemical parameters, such as yield, turbidity, viscosity, clarity, colour, polyphenol, protein, TSS, and total solid, were measured as dependent variables. Process optimization has been done using Box-Behnken design. Optimization has been done for maximum yield percentage, L* value, a* value, protein, and polyphenol content, and minimum values for turbidity, viscosity, clarity, b* value, TSS, and total solid content. The suggested parameters for extraction of juice were at 0.05% enzyme concentration at 44 °C for 80 min. In a large-scale production, extraction of juice by Pectinase (Aspergillus aculeatus) has a significance importance due to its high yield as well as nutritional values.