Modification of Dietary Fibers to Valorize the By-Products of Cereal, Fruit and Vegetable Industry-A Review on Treatment Methods

Enhancing drying characteristics and quality of fruits and vegetables using biochemical drying improvers: A comprehensive review

Traditional drying is a highly energy-intensive process, accounting for approximately 15% of total manufacturing cost, it often resulting in reduced product quality due to low drying efficiency. Biological and chemical agents, referred to as biochemical drying improvers, are employed as pretreatments to enhance both drying characteristics and quality attributes of fruits and vegetables. This article provides a thorough examination of various biochemical drying improvers (including enzymes, microorganisms, edible film coatings, ethanol, organic acids, hyperosmotic solutions, ethyl oleate alkaline solutions, sulfites, cold plasma, carbon dioxide, ozone, inorganic alkaline agents, and inorganic salts) and their effects on improving the drying processes of fruits and vegetables. Additionally, it introduces physical drying improvers (including ultrasonic, pulsed electric field, vacuum, and others) to enhance the effects of biochemical drying improvers. Pretreatment with biochemical agents not only significantly enhances drying characteristics but also preserves or enhances the color, texture, and bioactive compound content of the dried products. Meanwhile, physical drying improvers reduce moisture diffusion resistance through physical modifications of the food materials, thus complementing biochemical drying improvers. This integrated approach mitigates the energy consumption and quality degradation typically associated with traditional drying methods. Overall, this review examines the role of biochemical agents in enhancing the drying characteristics and quality of fruits and vegetables, offering a comprehensive strategy for energy conservation and quality improvement.

Improving gel properties of egg white protein using coconut endosperm dietary fibers modified by ultrasound and dual enzymolysis combined with carboxymethylation or phosphate crosslinking

Coconut endosperm residue is a rich dietary fiber resource; however, its hydration properties are poor. To enhance the functionality and applications of coconut endosperm residue dietary fiber (CERDF) in the food industry, ultrasound, cellulase, and hemicellulase hydrolysis combined with carboxymethylation or phosphate crosslinking have been used. The impact of the modified CERDFs on egg white protein gel (EWPG) was also studied. Compared to unmodified CERDF, CERDF modified by ultrasound and dual enzymatic hydrolysis combined with carboxymethylation (CERDF-UDEC) or phosphate-crosslinking (CERDF-UDEPC) exhibited a larger surface area and improved water retention and expansion abilities (p < 0.05). Addition of CERDF, CERDF-UDEC, and CERDF-UDEPC increased the random coil content of EWPG and rendered its microstructure more granular. CERDF-UDEC and CERDF-UDEPC improved EWPG properties more effectively than unmodified CERDF. These enhancements included increased water retention, pH, hardness (from 109.87 to 222.38 g), chewiness (from 78.07 to 172.13 g), and gumminess (from 85.12 to 181.82), and a reduction in its freeze-thaw dehydration rate (from 33.66% to 16.26%) and transparency (p < 0.05). Adding CERDF and CERDF-UDEC (3-5 g/100 g) enhanced the gastric stability and intestinal digestibility of EWPG. Thus, CERDF modified through ultrasound and dual enzymolysis combined with carboxymethylation or crosslinking improved the gel properties of EWPG. However, further research is needed to clarify the mechanisms behind these modifications and evaluate their economic feasibility.

Effects of Modified Oil Palm Kernel Expeller Fiber Enhanced via Enzymolysis Combined with Hydroxypropylation or Crosslinking on the Properties of Heat-Induced Egg White Protein Gel

Due to its poor hydration properties, oil palm kernel expeller dietary fiber (OPKEDF) is rarely used in the food industry, especially in hydrogels, despite its advantages of high availability and low cost. To address this situation, the effects of enzymolysis combined with hydroxypropylation or crosslinking on the structure and hydration properties of OPKEDF were investigated, and the impact of these modified OPKEDFs on the properties of egg white protein gel (EWPG) was studied. Enzymolysis combined with hydroxypropylation or phosphate crosslinking improved the soluble fiber content (5.25-7.79 g/100 g), water-retention and expansion abilities of OPKEDF (p < 0.05). The addition of unmodified OPKEDF or modified OPKEDF increased the random coil content of EWPG and increased the density of its microstructure. Moreover, enzymolysis combined with hydroxypropylation or crosslinking enhanced the effect of OPKEDF on the properties of EWPG, including improvements in its water-retention ability, pH, hardness (from 97.96 to 195.00 g), chewiness (from 78.65 to 147.39 g), and gumminess (from 84.63 to 152.27) and a reduction in its transparency (p < 0.05). Additionally, OPKEDF and enzymolysis and hydroxypropylated OPKEDF increased the resilience (0.297 to 0.359), but OPKEDF treated via enzymolysis and crosslinking reduced it. Therefore, OPKEDF modified by means of enzymolysis in combination with hydroxypropylation or crosslinking improved the gel properties of EWPG. However, further work is required to determine the effects of these modifications on the nutritional profile, scalability, and economic feasibility of OPKEDF and egg white gel.

Millet Bran Dietary Fibers Modified by Heating and Enzymolysis Combined with Carboxymethylation, Acetylation, or Crosslinking: Influences on Properties of Heat-Induced Egg White Protein Gel

Applications of millet bran dietary fiber (MBDF) in the food industry are limited by its poor hydration properties. Herein, MBDF was modified by heating, xylanase and cellulase treatment separately combined with carboxymethylation, acetylation, and phosphate crosslinking, and the effects of the modified MBDFs on heat-induced egg white protein gel (H-EWG) were studied. The results showed that three composite modifications, especially heating and dual enzymolysis combined with carboxymethylation, increased the surface area, soluble fiber content, and hydration properties of MBDF (p < 0.05). MBDF and the modified MBDFs all made the microstructure of H-EWG denser and decreased its α-helix content. Three composite modifications, especially heating and dual enzymolysis combined with carboxymethylation, enhanced the improving effect of MBDF on the WRA (from 24.89 to 35.53 g/g), pH, hardness (from 139.93 to 323.20 g), chewiness, and gumminess of H-EWPG, and enhanced the gastric stability at 3-5 g/100 g. MBDFs modified with heating and dual enzymolysis combined with acetylation or crosslinking were more effective in increasing the antioxidant activity of the gastrointestinal hydrolysates of H-EWG than MBDF (p < 0.05). Overall, heating, xylanase and cellulase treatment separately combined with carboxymethylation, acetylation and crosslinking can enhance the hydration properties and the improving effect of millet bran fibers on H-EWG properties.

Modification, biological activity, applications, and future trends of citrus fiber as a functional component: A comprehensive review

Citrus fiber, a by-product of citrus processing that has significant nutritional and bioactive properties, has gained attention as a promising raw material with extensive developmental potential in the food, pharmaceutical, and feed industries. However, the lack of in-depth understanding regarding citrus fiber, including its structure, modification, mechanism of action, and potential applications is holding back its development and utilization in functional foods and drugs. This review explores the status of extraction methods and modifications applied to citrus fiber to augment its health benefits. With the aim of introducing readers to the potential health benefits of citrus fibers, we have placed special emphasis on their regulatory mechanisms in the context of various conditions, including type 2 diabetes mellitus, cardiovascular disease, obesity, and cancer. Furthermore, this review highlights the applications and prospects of citrus fiber, aiming to provide a theoretical basis for the utilization and exploration of this valuable resource.

Influence of Three Modification Methods on the Structure, Physicochemical, and Functional Properties of Insoluble Dietary Fiber from Rosa roxburghii Tratt Pomace

Rosa roxburghii Tratt pomace is rich in insoluble dietary fiber (IDF). This study aimed to investigate the influence of three modification methods on Rosa roxburghii Tratt pomace insoluble dietary fiber (RIDF). The three modified RIDFs, named U-RIDF, C-RIDF, and UC-RIDF, were prepared using ultrasound, cellulase, and a combination of ultrasound and cellulase methods, respectively. The structure, physicochemical characteristics, and functional properties of the raw RIDF and modified RIDF were comparatively analyzed. The results showed that all three modification methods, especially the ultrasound-cellulase combination treatment, increased the soluble dietary fiber (SDF) content of RIDF, while also causing a transition in surface morphology from smooth and dense to wrinkled and loose structures. Compared with the raw RIDF, the modified RIDF, particularly UC-RIDF, displayed significantly improved water-holding capacity (WHC), oil-binding capacity (OHC), and swelling capacity (SC), with increases of 12.0%, 84.7%, and 91.3%, respectively. Additionally, UC-RIDF demonstrated the highest nitrite ion adsorption capacity (NIAC), cholesterol adsorption capacity (CAC), and bile salt adsorption capacity (BSAC). In summary, the combination of ultrasound and cellulase treatment proved to be an efficient approach for modifying IDF from RRTP, with the potential for developing a functional food ingredient.

The effects of different fiber fractions from sour cherry (Prunus cerasus L.) pomace and fiber modification methods on cake quality

Sour cherry pomace is the largest byproduct of sour cherry processing with more than 0.4 million tonnes per year. In this study, sour cherry pomace powder (SCPP) has been treated individually or by a combination of microwave (MW), enzymatic hydrolysis, and high pressure to increase soluble dietary fiber (SDF) content. Then, the untreated or treated forms of SCPP, their SDF, and insoluble dietary fiber (IDF) isolates were added (5%) to the reduced-fat cake. Rheological, physical, and textural properties of the full-fat (50%) and the reduced-fat (25% fat) cakes enriched with dietary fiber (DF) were compared. SDF enrichment minimized the negative effect of fat reduction in the cake. Water absorption, mixing tolerance, hardness, and springiness values of the SDF-enriched samples were found as the lowest. Extensibility, energy, weight loss, and cohesiveness values were found to be the highest values with the addition of SDF. All treatments helped to decrease mixing tolerance, dough development, and stability time. MW was the critical treatment for DF modification. Individual MW-treated DF samples increased resistance to extension of the dough samples as compared to the untreated SDF, IDF, and SCPP. Nevertheless, SDF showed better performance in acting as a fat replacer than IDF and SCPP. PRACTICAL APPLICATION: The soluble dietary fiber (SDF) isolate minimized the negative effect of fat reduction in cakes. Water absorption and mixing tolerance of the dough were measured as the lowest. The hardness and springiness of soluble dietary fiber-enriched cakes were found to be the lowest. Extensibility and weight loss reached the highest value when SDF was used. Treatments helped decrease mixing tolerance, dough development, and stability time.