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Processing efficiency of rainbow trout, amounts of by-products and their nutritional value as well as some correlations between whole fish weight and products yield were evaluated. Results showed that efficiency decreased up to 87.56 ± 3.43% for gutted fish and it reached up to 56.69 ± 3.26% and 45.36 ± 2.37% for skined on and skinless fillets, respectively. The highest amounts of by-product were related to head and viscera which were 15.52 ± 2.00% and 12.62 ± 2.61% of body weight, respectively. A significant negative correlation was found between fish weight and head weight percentage (P<0.01). Also, the yield of headed and gutted product increased significantly by increase in fish weight (P<0.01). Among by-products, viscera and head were the richest sources of fat (17.4 and 13.0 % of wet weight) and skin contained the highest amount of protein (24.1% of wet weight). Moreover, a significant presence of the most important and health benficial omega-3 fatty acids was detected in both head and viscera. Viscera and bone were also found as rich source of iron mineral.

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In this study Response Surface Methodology (RSM) was employed to investigate the effects of different operating conditions on the hydrolysation process of poultry by-products protein by the alcalase. Central Composite Design (CCD) by 5-level and 3-factor was used for the optimization of the hydrolysate production and to evaluate the effects and interactions of process variables: time (minute), temperature (C^◦) and enzyme to substrate ratio on the response. The response was included degree of hydrolysation (%). The mathematical model showed good fit with the experimental data, since the R² of 0.96 indicated that 96% of the variability within the range of values studied could be explained by the model. Furthermore lake of fit of the model was not significant (p<0.05). The optimum conditions for production of poultry by-products protein hydrolysate by 15.24% degree of hydrolysis were established as an enzyme activity to substrate ratio 0.07 AU/g protein; time 127.69 minute, and temperature 52.51°C. According to amino acid analysis and chemical score, methionine and histidine was the limiting amino acids in the hydrolysate. The poultry by-products protein hydrolysate tends to be a potential source in balanced fish diets and functional additive in food industries.

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Although biosurfactants have great advantages over chemical surfactants, their wider industrial applications have been constrained by their relatively high production cost. Using renewable, sustainable and cheap substrates such as different industrial by-products and wastes maybe decrease biosurfactant production costs. Since in different countries, there are a variety of by-products and wastes so use of these substrates rely on their types and concentrations in countries. In addition to hydrocarbon compounds, molasses has been considered as a dominant by-product in Iran. In this study, among 16 crude oil degrading isolates, strain Pseudomonas aeruginosa ZN was selected as an efficient biosurfactant producer by screening methods for detection of biosurfactant producing bacteria. For investigation of molasses concentrations effect on bacterial growth and biosurfactant production, a wide range of molasses concentrations from 2-12% (v/v) were used. This strain was able to grow and produce biosurfactant in all range of molasses concentrations while the best concentrations were 4-6%. Also, at the optimum molasses concentration, reduction of surface tension from 70 to 32-34 mN/m was observed. The concnetrations more than these values decreased the growth and production process. Acid precipitation and solvent extract (ethyl acetate: hexane) methods were carried out for recovery of biosurfactant from the culture broth, then results of spraying on developed TLC and staining fermentation broth without bacterial cells showed the two produced biosurfactants were glycolipid.

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Shrimp by-products can be used as the cheapest raw material to extract bioactive compounds such as lipid extract rich in carotenoid pigments.  The aim of this study was to investigate the nutritional composition of shrimp by-product powder, maximize the extraction efficiency of carotenoid extract using ethanol, hexane, hexane/acetone, and hexane/isopropyl alcohol solvents, and also evaluate the effect of solvent type on the solubility and antioxidant properties of carotenoid extract. According to the results, the shrimp by-product powder contained 53.11% protein, 4.51% moisture, 28.58% ash, 3.45% fat, and 10.45% carbohydrate. The results also showed that using a mixed solvent of hexane/isopropyl alcohol (1:1 ratio) resulted in the highest extraction efficiency of 1.81 g/100 g of dry powder, while the extraction efficiency with ethanol, hexane, and hexane/acetone solvents was 1.53, 1.42, and 1.17 g/100 g of dry powder, respectively. The results of the extract solubility test also showed that the lipid extracted with ethanol solvent has the highest water solubility and the highest antioxidant property (up to 99.10%). In general, the results of this study showed that the use of polar solvents can increase the solubility of carotenoid extract extracted from shrimp by-products and facilitate one of the most important challenges of using this compound in the food and pharmaceutical industries.

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Collagen, which is widely distributed in pluricellular animals, is one of the most fundamental constituents of the extracellular matrix, and plays mechanically or physiologically important roles in their bodies. In this study, the biochemical and physical characteristics of pepsin-solubilized collagen from the mantle of Yesso scallop (YMPC), a by-product of processing, was determined. Electrophoretic patterns showed that scallop mantle collagen contained α1 and α2 chains, which was similar to the patterns of bovine tendon type V collagen. The YMPC showed different profiles in molecular, amino acids, peptide maps from those of bovine tendon collagen and lower denaturation temperature. Electron microscopic view of YMPC showed a sponge-like structure in part. These results indicated that YMPC may become a sustainable source of useful collagens for various purposes including value-added biomaterials. It may also be useful in a variety of applications as an alternative of vertebrate collagen, which has been widely used.

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Most of dyes used in production processes caused serious environmental pollution when discharged into the environment. Azo dyes are the most used synthetic compounds in the textile, food, leather and cosmetic industries. Due to their toxicity and hard degradation, these kinds of compounds are classified as environmental hazardous materials that have to be treated before discharging to the environment. Acid orange 7 (AO7) is one of azo dyes that is resistant to aerobic degradation and under anaerobic condition is reduced to potential carcinogenic aromatic amines. Different physical methods such as adsorption, ultrafiltration, reverse osmosis, coagulation and electro coagulation are widely used for efficient dye removal but they just transport contaminants from water to sludge and generate secondary wastes which need more treatment. Advanced oxidation processes (AOPs) are suitable to mineralize dye wastewater. They are almost characterized by the efficient production of hydroxyl radicals. Radicals are highly reactive oxidant. Ozonation and photocatalytic treatment are often applied for decolorization of dye wastewaters. It is reported that ozone is an effective agent for reducing the color of wastewater especially azo dyes. TiO2 photocatalytic process is safe and does not require expensive oxidants, against ozonation. This process classified as an AOP method and can be carried out at mild temperature and pressure. The purpose of this study was to investigate hybrid photocatalytic and ozonation processes. Therefore, according to debarment of light penetration in dye wastewater, decoloration ability of ozone was used for improving photocatalytic process efficiency in a hybrid process. The effect of pH, dye and nano catalyst concentration, irradiation source power and ozone injection rate were investigated on removal efficiency in this process. Dye removal efficiencies decreased with increase in dye concentration and decrease in pH, ozone injection rate, catalyst concentration and irradiation source power. Optimum conditions of the process was occurred in pH of 9, UV-A lamp of 120 W, and nano material concentration of 128 mg/L with 50 mg/L of dye concentration and 20 mg/min of ozone injected (with 1 bar pressure and 1 lit/min of gas flow). In these conditions, dye removal was completed after 65 minutes. The result confirm the cleavage of the azo bonds, benzene and naphthalene rings as a result of treatment. The intensities of the absorbance peak at 485nm decrease rather fast than 230 and 310 nm. This shows that faster degradation of azo band in comparison with benzene and naphthalene rings. GC-MS analysis was performed to identify the intermediate products of process. According to GC-Mass test, 5-amino-1-naphthol, 1-naphthol and benzene compound (phenol, aniline and phthalic acid) were in decolorized solution. These compounds concentration increased in the first hour and then decreased. 3 and 7 hour were needed to reach optimum condition for removing naphthalene and benzene compounds, respectively. Reaction was followed by first order kinetic and was fitted to langmuir–hinshelwood model in optimum condition in all cases. First order reaction rate of decoloration (K) decreased with increase in dye concentration and decrease in pH, catalyst concentration and irradiation source power.

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In this study, the effect of different treatments including method 1- homogenized by-product (BP-FPI), method 2- washing of homogenized by-product by distilled water (WBP-FPI), method 3- washing of homogenized by-product by CaCl₂-citric acid (CaCi-BPFPI), method 4- CaCl₂-citric acid treated –washing by distilled water (CaCi-W- BPFPI), method 5- washing by distilled water- CaCl₂-citric acid treatment (W-CaCi-BPFPI) on composition of protein isolate from rainbow trout (Oncorhynchus mykiss) by-product were investigated. Washing by distilled water (method 2) and distilled water + combination of CaCl₂ + citric acid (method 5) had significant effect on heme iron and phospholipid (P < 0.05). Washing methods influenced protein yield and the lowest yield (9.4%) was obtained using method 5 (P < 0.05). Washing-derived proteins were lighter in color compared with that obtained from by-product. Method 1 resulted in higher redness (9.36) while that obtained with method 5 showed the lowest redness (1.19) (P < 0.05). Protein hydrolysate produced from method 5 protein isolate had high antioxidant activity in a dose-dependent manner.  Additionally, the presence of small peptides in hydrolysate contributed to its anti-diabetic activities. Results indicated that washing by distilled water (method 2) or combined with CaCl₂ + citric acid (method 5) is necessary for production of protein isolate from rainbow trout processing by-product.
 

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Gelatin has many applications in the food, pharmaceutical and cosmetic industries due to its technological and functional properties. By-products from fish cleaning are rich sources of collagen. The physical, chemical and rheological properties of gelatin or collagen depend on their sources as well as the extraction conditions. Response surface methodology (RSM) with three parameters was conducted to determine the optimum extraction conditions of gelatin from Caspian whitefish scale. A Box-Behnken design was used to study the combined effects of sodium hydroxide concentration (0.075-0.225 M), soaking time in sodium hydroxide solution (60-180 minute), and extraction temperature (30-50 ^oC) were determined. Viscosity (cp), gel strength (g), L*, a*, and b* were chosen as responses. The results showed the optimum conditions were sodium hydroxide concentration 0.109 M, soaking time in sodium hydroxide solution of 115.735 minutes, and Extraction temperature of 37.585^oC. The predicted responses including viscosity, gel strength, L*, a*, and b* were 2.17 cP, 145 g, 6.039, 6.801, and 38.859 respectively. The response surface method was able to estimate the optimal conditions of extraction gelatin with high desirability (0.99).
 

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Limited data exist about the production of extruded linseed as a feed ingredient in farm animal nutrition. The objective of this study was to produce and evaluate extruded linseed mixed with alfalfa hay, pistachio by-products, and sugar beet pulp or corn grain in different proportions of linseed: alfalfa hay: pistachio by-products at ratios of 70:15:15, 70:20:10, 70:10:20, and 80:10:10 for quality parameters and in situ rumen Dry Matter (DM) degradability. Using a completely randomized design, the treatment containing alfalfa hay had higher Extrusion Effectiveness (EE), Water Holding Capacity (WHC), and Angle of Repose (AR), but lower Oil Loss (OL) and Bulk Density (BD) than other treatments (P< 0.05). There were no differences among extruded linseed products with different ratios of linseed: alfalfa: pistachio by-products for EE, WHC, and AR (P> 0.05). The treatment with an 80:10:10 ratio had the highest OL among all treatments and the treatment with a 70:15:15 ratio had lower BD than the others (P< 0.05). The DM degradability parameters of extruded products was affected by the absorbents and the treatment containing alfalfa hay had higher potential DM degradability than other treatments (P< 0.05). In conclusion, extruded treatment with alfalfa hay had the highest EE, oil retention capacity and potential rumen DM degradability compared to other treatments. In addition, extruded linseed product with an 80:10:10 ratio of linseed: alfalfa hay: pistachio by-products had higher OL than the other ratios.

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According to FAO reports, a huge amount of fish processing by-products (around 50%) are produced every day. Fish processing by-products are mainly head, tail, skin, scale, backbone and viscera.  These by-products usually consist of several bioactive materials, such as proteins, enzymes, fatty acids, and biopolymers. Seafood by-products could be a source of healthy food for both human (such as fish sauce, fish protein hydrolysate; FPH) and animals (such as fish meal, fish silage, FPH).  Additionally, bioactive substances derived from seafood by-products have been used in various biotechnological, nutritional, pharmaceutical, and biomedical applications. FPH is one of the most important products which is prepared by hydrolysis of underutilized fish or fish processing by-products. Although FPH has been used for agricultural purposes, advanced technological developments have made it possible to apply these FPHs as functional ingredients in food and pharmaceuticals. Likewise, the hydrolysate is also a rich source of biologically active small peptides that have been proved for various therapeutic potentials. This paper will review properties and potential applications of FPH in the human nutrition.

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Date press cake is a by-product of date fruit juicing that has remained underutilized in the food industry. This is mostly due to the lack of information and technical knowledge about its chemical composition, nutritional value, health benefits and possible effects on the quality of food products upon inclusion. The main aim of this research was to determine the chemical composition, bioactive compounds and functional properties of date press cake to promote its food applications as an economical and available functional ingredient. The research was carried out on ground date press cake obtained from Shahani dates with two particle sizes of 355 µm (coarse) and 167 µm (fine). On average, Shahani date press cake contained 13.37% moisture, 4.92% fat, 6.35% protein, 11.74% crude fiber and 79.06% carbohydrate. Fructose was the main simple sugar, magnesium was the major mineral, oleic acid was the predominant fatty acid, and phenolic compounds were the main antioxidant. The chemical composition and functional properties of the date press cake were affected by its particle size. The coarse sample had lower fibre, oleic acid, total phenolic and flavonoid content and antioxidant activity than the fine sample. However, the fine sample had higher sugar and fat content and exhibited higher water holding capacity and solubility than the coarse sample.
 

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The effects of storage of rainbow trout processing by-products at 4 ºC on fatty acid composition and nutritional values of hydrolyzed-derived oils were determined. Polyunsaturated fatty acids (PUFA, 39.97-43.70%) were the major fatty acids followed by monounsaturated (MUFA, 31.90-34.05%) and saturated (SFA, 19.27-22.59%) fatty acids. Among fatty acids, linoleic, cis vaccinic, and palmitic were the main fatty acids. N-6 fatty acids represented 34-38% while n-3 fatty acids were 4.5-6.6% of all fatty acids (P<0.05). Hypocholesterolemic/hypercholesterolemic ratio (h/H) index in oils was between 4.23 and 5.15. The highest value was found at day 2 while showed no changes among other storage times (P>0.05). Thrombogenic index (TI) at days 0 and 2 were the lowest among storage times while at days 5 it represented the highest value. However, the change was not significant (P>0.05). N-6/n-3 ratio ranged from 5.01 to 7.6. PUFA/SFA was between 1.77 and 2.29 and showed the highest value at day 2 while after 5 days significantly decreased (P<0.05). The highest fish lipid quality (FLQ) index was for fresh by-products (day 0) (P<0.05) and showed no differences from day 1 to 5 (P>0.05). Also, nutritive value index (NVI) ranged from 2.25 to 2.55 with no significant differences during storage (P>0.05). The sum of EPA and DHA was between 1.73 and 4.05% and decreased with increasing storage days (P<0.05). Polyene index (PI) decreased to the end of storage time up to 4 days compared with the fresh by-products and significantly decreased thereafter after 5 days (P<0.05). Results of the present study showed that fatty acid composition and nutritional quality of oils from hydrolysis-derived oils were influenced by the storage days to some degree.
 

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Date Press Cake (DPC) is a by-product of date fruit juicing, which has remained mostly underutilized in food products. The main objective of this research was to investigate the viability of adding DPC in cake formulation. Thus, different levels (0, 10, 20, 30, and 40%) and particle sizes (210 µm= DPC₂₁₀ and 500 µm= DPC₅₀₀) of DPC were used in cake formulation. The results showed that DPC had higher fiber, ash, and fat content than cake flour. Increasing the level and reducing the particle size of DPC increased batter consistency, firmness, stickiness, cohesiveness and viscosity. Inclusion of DPC increased cake density, reduced pH and crust moisture content, but these were not affected by DPC particle size. The samples became harder and less cohesive as the level of DPC increased. DPC₂₁₀ resulted in softer and less cohesive cakes compared to the DPC₅₀₀. Addition of DPC improved the antioxidant content of the cakes, particularly when DPC₂₁₀ was added. Overall, the sample produced with 10% DPC₂₁₀ had acceptable sensory characteristics.