Food Biotechnology
Soheyl Reyhani Poul; Sakineh Yeganeh; Reza Safari
Abstract
IntroductionOne of the synthetic and harmful preservatives used in sausage formulation is sodium nitrite. This compound helps to increase the shelf life and marketability of meat products by preventing the growth of anaerobic bacteria, especially clostridium, exerting an antioxidant effect, stabilizing ...
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IntroductionOne of the synthetic and harmful preservatives used in sausage formulation is sodium nitrite. This compound helps to increase the shelf life and marketability of meat products by preventing the growth of anaerobic bacteria, especially clostridium, exerting an antioxidant effect, stabilizing the red color of meat and improving the taste. Despite these benefits, sodium nitrite is very dangerous for health and it can cause malignant diseases. For this reason, it is necessary to replace this substance using a natural preservative. Pigments extracted from aquatics such as astaxanthin due to having antioxidant activity, antimicrobial properties and pink color may be a good substitute for sodium nitrite. However, these pigments must be nanoencapsulated at first due to their sensitivity to food processing conditions, including high temperatures. The aim of the current research at the first was to extract astaxanthin from Haematococcus pluvialis microalgae using the acid-acetone method and pigment nanoencapsulation using maltodextrin-sodium caseinate combined coating. Then, sodium nitrite in the sausage formulation was replaced by the carrier nanocapsules with different proportions and oxidative and microbial spoilage tests, color and sensory evaluations were performed for different treatments. Materials and MethodsAt first, astaxanthin pigment was extracted from Haematococcus pluvialis using the acid-acetone technique. Then, the extracted pigment was nanoencapsulated using maltodextrin-sodium caseinate combined coating and the resulting (carrier) nanocapsules in the form of treatments A (120 mg/kg sodium nitrite), B (120 mg/kg nanocapsules carrying astaxanthin), C (90 mg/kg sodium nitrite+30 mg/kg nanocapsules carrying astaxanthin), D (60 mg/kg sodium nitrite+60 mg/kg nanocapsules carrying astaxanthin) and E (30 mg/kg sodium nitrite+90 mg/kg nanocapsules carrying astaxanthin) were replaced sodium nitrite in the sausage formulation. These treatments were evaluated in terms of oxidative and microbial spoilage, color indices and sensory properties during 28 days of storage at refrigerator along with the control (without sodium nitrite and carrier nanocapsules). This research was conducted in a completely randomized design. Data were analyzed by one-way analysis of variance and the difference between the means was evaluated by Duncan's test at 95% confidence level. Results and DiscussionAccording to the results, the lowest levels of thiobarbituric acid and peroxide value during the storage period were related to treatments B, E and D (p>0.05). Treatments A and C had no significant difference in terms of thiobarbituric acid and peroxide value until day 14 (p>0.05), but with increasing storage time, this difference became significant and treatment A showed higher values (p<0.05). The results of this section showed that the power of astaxanthin in controlling oxidative spoilage is significantly greater than sodium nitrite, and if the purpose is only to control this type of spoilage, there is no need to replace or use sodium nitrite. The results also showed that in terms of controlling microbial spoilage, sodium nitrite has more power than nanocapsules carrying astaxanthin. So that, the lowest amount of total volatile basic nitrogen (TVB-N) and the most standardized pH were related to treatments A, C and D (p>0.05) during the storage period (p<0.05). Treatments B and E (p>0.05) were ranked next (p<0.05) in terms of the two mentioned indicators. The results of this section showed that if sodium nitrite reduced from 120 mg/kg to 60 mg/kg and replaced by nanocapsules carrying astaxanthin in the sausage formulation, the resulting product has the same antimicrobial power as the product containing 120 mg/kg sodium nitrite. Evaluation of the color and sensory properties of treatments showed that A, C and D treatments are at a higher level than B, E (treatments) and control in terms of color indices and general acceptance (p<0.05). The comparison of the color indices and sensory properties of the treatments on days 0 and 28 of storage at refrigerator showed that the color and sensory indices remained constant in the formulated treatments, unlike the control. Conclusion Nanocapsules carrying astaxanthin with maltodextrin-sodium caseinate combined coating as a natural product with many properties in health, control and prevention of various diseases, have a high efficiency to replace the sodium nitrite in sausage formulation. So that, if 30 to 60 mg/kg of the permissible limit of 120 mg/kg of sodium nitrite in the sausage formulation is replaced by nanocapsules carrying astaxanthin, the resulting product will be similar to the product containing 120 mg/kg of sodium nitrite in terms of shelf life, resistance to oxidative and microbial spoilage, color indices and sensory properties.
Food Biotechnology
Soheyl Reyhani Poul; Sakineh Yeganeh; Zeynab Raftani Amiri
Abstract
Introduction Since heat treatments and special standards are not used in the production of traditional (homemade) tomato paste, fungal and bacterial spoilage in the product occurs extensively during storage in the refrigerator (4°C). Astaxanthin extracted from aquatics has antimicrobial activity ...
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Introduction Since heat treatments and special standards are not used in the production of traditional (homemade) tomato paste, fungal and bacterial spoilage in the product occurs extensively during storage in the refrigerator (4°C). Astaxanthin extracted from aquatics has antimicrobial activity and color similar to tomato and can probably be effective in preventing spoilage of tomato paste. In addition, astaxanthin has other properties in the field of preventing and controlling diseases and maintaining human health, which justifies its use in food formulations as an enrichment. Since heat, enzyme, acid, etc. treatments are practiced during the production of tomato paste, these factors may change the structure and thus the function of astaxanthin. For this reason, astaxanthin nanoencapsulation is necessary for its use in tomato paste formulation. Materials and Methods In this research, first, astaxanthin was extracted from Haematococcus pluvialis microalgae using the acid-acetone combined method. Then, this pigment was nanoencapsulated using maltodextrin-sodium caseinate coating and the resulting nanocapsules were used together with the pure form of astaxanthin in the formulation of tomato paste. The research treatments were control, tomato pastes containing 3 and 6% astaxanthin (A and B, respectively) and also 3, 6 and 9% nanocapsules carrying the pigment (C, D and E, respectively). These treatments were kept at refrigerator for 28 days and were evaluated (on days 0, 7, 14, 21 and 28) in terms of the total number of fungi, Howard's number (HMC), pH, fungal flora, total bacteria count, amount of lactic acid bacteria and sensory properties. This research was conducted in a completely randomized design. Data were analyzed by One-way Anova and the difference between the means was evaluated by Duncan's test at 95% confidence level. Results and Discussion The results showed that the fungi proliferation, total count and lactic acid bacteria were slower than the control during the storage period in the treatments containing astaxanthin and its carrying nanocapsules, and the minimum number of the mentioned microorganisms and Howard's number were related to treatments D and E (p>0.05). Treatments C, B and A were ranked next in this respect (p<0.05). The number of fungi in two treatments D and E from day 0 to 28 varied from 128 to 332 cfu/gr. Also, the Howard number of these treatments was recorded from 18 to 34% in the mentioned time period. However, these two indices in the control ranged from 121 to 792 cfu/gr and 18 to 91%, respectively, during the storage period. The count of total bacteria and the amount of lactic acid bacteria in the control on day 28 were equal to 8.9 cfu/gr and 311 mg/kg, respectively, but these two values were recorded in the E and D treatments on the same day, about 4.8 cfu/gr and 110 mg/kg, respectively. Counting the total number of fungi, bacterias and also Howard's number in control and other treatments showed that the effect of nanocapsules carrying astaxanthin on microbial growth and proliferation is significantly greater than pure astaxanthin (p<0.05). The pH of the treatments varied from 3.9 to 5.8 during the storage period and the most standardized pH (3.9-4.4) was recorded in C, D and E (p>0.05) treatments (p<0.05). The pH of two treatments A and B (p>0.05) was higher than the three mentioned treatments and lower than the control (p<0.05). This finding showed that nanocapsules carrying astaxanthin have a greater effect on controlling the pH of tomato paste than pure astaxanthin during storage at refrigerator (p<0.05). The identification of the fungal flora of the treatments on the 28th day confirmed that two genus of Penicillium and Aspergillus form the main flora of the product. The results of the sensory evaluation of the treatments on day 0 showed that adding astaxanthin and its carrier nanocapsules does not change the color, aroma, taste and texture indicators (subsequently the general acceptance) of tomato paste (p>0.05). On the 28th day, the mentioned sensory indices only in the two treatments D and E were not significantly different from the 0 day, but they changed negatively in the other treatments (p<0.05). Conclusion According to the findings of the present research, astaxanthin extracted from Haematococcus pluvialis microalgae has the ability to inhibit fungal and bacterial spoilage and stabilize the sensory properties of tomato paste stored at refrigerator. This properties were improved by adding nanoencapsulated pigment using maltodextrin-sodium caseinate combined coating. Since there were no significant differences between the two treatments containing 6% and 9% of nanocapsules carrying astaxanthin (D and E) in terms of quality indices and microbial spoilage, therefore, the treatment containing 6% nanocapsules is introduced as the optimal treatment.
Food Technology
Reza Safari; Soheil Reyhani Poul
Abstract
Introduction Phycocyanin is one of the pigments used in the food industry due to its antioxidant and antibacterial as well as coloring properties. This pigment is commercially produced from Spirulina platensis microalgae, in the form of photoautotrophic cultures and in open environments in large ...
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Introduction Phycocyanin is one of the pigments used in the food industry due to its antioxidant and antibacterial as well as coloring properties. This pigment is commercially produced from Spirulina platensis microalgae, in the form of photoautotrophic cultures and in open environments in large ponds or pools in tropical or subtropical areas at the edges of oceans. Different techniques are used in order to extract phycocyanin from spirulina microalgae.. Each technique has its own advantages and disadvantages besides different efficiency. These methods include freezing-defrosting, enzymatic, ultrasound, high hydrostatic pressure, ultracentrifuge, ultra homogenization, extraction using water and various solvents. Of course recently, the production of recombinant phycocyanin has been considered as a suitable option for the production of heterotrophic phycocyanin. The purpose of the current research was to cultivate Spirulina platensis, evaluation of the microalgae growth process, and comparison of the efficiency of different methods in the extraction of phycocyanin pigment. Materials and Methods The pure sample of Spirulina platensis microalgae was prepared from Algaeology Laboratory, Biology Department of Tarbiat Modares University. For the cultivation of spirulina, Zarrouk culture medium with different compositions was used, and after cultivation in smaller scales (100 and 500 ml), the final cultivation was carried out in volumes of 5 and 50 liters. After cultivating the microalgae and exposing them to fluorescent light with appropriate light lux intensity (3500 to 8000) and a period of 12 hours of darkness and 12 hours of light, the samples were placed at 29 °C for 16 days. In order to evaluate the growth process of the algal mass, the absorbance of the solution containing the algal cells was read at a wavelength of 540 nm. After preparing the dry mass of spirulina microalgae, four methods of ultrasound, freezing-defrosting, enzymatic and mineral solvent technique were used to extract phycocyanin. In the next steps, the efficiency of each method was evaluated by measuring the concentration and purity of phycocyanin. In addition, the effect of applying the purification process by ammonium sulfate on the concentration and purity of the extracted pigment was also evaluated. This research was conducted in a completely randomized design and SPSS and EXCEL softwares were used for statistical analysis and drawing of diagram, respectively. Data were analyzed using one-way analysis of variance and the difference between the means was evaluated by Duncan's test at 95% confidence level. Results and Discussion The results showed that microalgae growth from day 0 to 14 had an upward trend and the resulting changes were significant at all times, except days 14 and 16 (p<0.05). Also, after passing the short resting phase (2 days), the microalgae entered the logarithmic growth phase and continued to grow until the 14th day, but between the 14th and 16th days, the growth was almost constant. In the following, it was found that the mass produced after 16 days is 1120 mg/l. The concentration of phycocyanin extracted in enzymatic and ultrasound methods (1.815 and 1.786 mg/ml, respectively) had no significant difference (p>0.05) and was at a higher level than the other two methods (p<0.05); In addition, the pigment concentration was higher in the freezing-defrosting technique (1.535 mg/ml) than in the mineral solvent method (1.121 mg/ml). After purification of the pigment using ammonium sulfate, the pigment concentration and purity increased significantly in each method (p<0.05). The results of this research showed that by choosing the optimal method and applying the purification process using ammonium sulfate, the extraction efficiency of phycocyanin from Spirulina microalgae (Spirulina platensis) could be increased. Conclusion Based on the results of this research, the growth trend of Spirulina platensis in Zarrouk culture medium was ascending first and then constant (during 16 days). Ultrasound technique and enzymatic method (lysozyme enzyme) to extract phycocyanin pigment from Spirulina platensis microalgae have more efficiency than freezing-defrosting and inorganic solvent (hydrochloric acid) methods. Also, purification of the extracted pigment using 40% ammonium sulfate increases the concentration and purity of phycocyanin in each method.
Food Chemistry
Reza Safari; Seyed Vali Hosseini; Sharareh Firouzkandian; Soheyl Reyhani Poul; Mona Zamani
Abstract
[1]Introduction: One way to turn chicken waste into high value-added product is to produce fermented silage (biosilage). This product is superior to fish powder due to its characteristics such as high quality protein, probiotic bacteria and low price and can be considered as a suitable alternative for ...
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[1]Introduction: One way to turn chicken waste into high value-added product is to produce fermented silage (biosilage). This product is superior to fish powder due to its characteristics such as high quality protein, probiotic bacteria and low price and can be considered as a suitable alternative for feed industry. Silage can be produced from protein wastes by both acidic and biological methods. The acidic method of producing silage (acidic silage) uses a variety of organic and inorganic acids such as formic acid and sulfuric acid. In the production of biological silage, two methods of autolysis (using internal enzymes) and fermentation (using microbial starters) are used. Starters used for inoculation are mainly from the group of lactic acid bacteria. To produce silage, protein wastes are used, especially fish wastes. Since poultry waste has not been used for biosilage production in the country so far, the aim of the present study is to produce biological silage from chicken waste and evaluate the profile of amino acids and fatty acids in the biosilage. Materials and methods: Chicken intestine was prepared from meat production complex in Golestan province, Kordkoy city and also Simin Naz poultry industrial slaughterhouse in Sari and was transferred to the processing pilot of Caspian Sea Ecology Research Institute in the shortest time in cold container. During the biosilage production process, protein-degrading bacteria (containing protease enzymes such as gram-positive sporulated bacteria) and acid-producing bacteria (to reduce the pH of the suspension and accelerate the fermentation process, such as lactic acid bacteria) were used as initiator bacteria or microbial starters for intestinal digestion. The product was analyzed for protein, fat, moisture and ash according to standard methods. In this study, high performance liquid chromatography (HPLC) of Cecil model (Seri 200) was used for amino acids analysis. Samples were prepared for assaying amino acids profile in two stages including hydrolysis and derivatization and the results were expressed in grams per 100 grams of substrate. To determine the fatty acids composition of the biosilage sample, the fat was first extracted. In order to evaluate the profile of fatty acids, a Shimadzu model gas chromatography device was used and the results were expressed as a percentage. Results and discussion: The product produced contained about 60% protein and 21% fat. According to the results, the total of essential amino acids in the produced biosilage was 24.416, the total of non-essential amino acids was 30.959 and the total of essential and non-essential amino acids was 55.375 g per 100 g of substrate. Among essentialamino acids, the highest amount belonged to the amino acids leucine (7.334±0.45 g/100g) and valine (4.71±0.27 g/100g) and among non-essential amino acids, the highest amount belonged to glutamic acid (10.6±0.73 g/100g) and alanine (5.864±0.81 g/100g). It was also found that all essential amino acids except tryptophan are present in biosilage. Evaluation of biosilage fatty acids profile revealed that the total amount of saturated fatty acids (SFA) was 33.57%, monounsaturated fatty acids (MUFA) was 41.17% and polyunsaturated fatty acids (PUFA) was 24.36%. It was further found that in biosilage the total omega 3 was 2.07%, the total omega 6 was 22.91% and the sum of EPA and DHA was 2.06%.The profile of amino acids and fatty acids in the biosilage produced from chicken waste is almost the same as that of other products made from protein waste (such as fish meal, fish waste biosilage and hydrolyzed protein powder). This property, along with cheap production and high nutritional value, allows the use of biosilage obtained from chicken waste in the livestock, poultry and aquatics feed industry.
Soheyl Reyhani Poul; Sakineh Yeganeh; Reza Safari
Abstract
[1]Introduction: Nisin is one of the antimicrobial substances that is used today as a preservative in various foodstuffs. It is a bacteriocin comprised of 34 amino acids and a molecular weight of 3.5 Da. With all the benefits of nisin, there are barriers to its use in dairy and protein rich products. ...
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[1]Introduction: Nisin is one of the antimicrobial substances that is used today as a preservative in various foodstuffs. It is a bacteriocin comprised of 34 amino acids and a molecular weight of 3.5 Da. With all the benefits of nisin, there are barriers to its use in dairy and protein rich products. One of these barriers is the combination of nisin with fats, proteins and sugars and the consequent reduction of its antibacterial activity. In the food science and industry, the use of the technique of encapsulation and production of liposome is the best possible solution in such cases. Also, by adding an antimicrobial agent such as chitosan to the coating of nanoliposomes, the antibacterial activity of the product may be increased. The aim of the present research was to produce nanoliposomes carrying nisin with (and without) chitosan coating and to evaluate the physical and antibacterial properties against two gram-positive bacteria, Bacillus cereus and Staphylococcus aureus. Materials and Methods: In this study, four treatments of nanoliposomes carrying nisin (NN), nanoliposomes carrying nisin coated with chitosan 0.05% ((NN-CH (0.05)), nanoliposomes carrying nisin coated with chitosan 0.1% (NN-CH (0.1)) and nanoliposomes carrying nisin coated with chitosan 0.5% (NN-CH (0.5)) were prepared and examined in terms of physical properties (average particle size, particle dispersity index, zeta potential and encapsulation efficiency) and antibacterial activity (against two gram-positive bacteria, Bacillus cereus and Staphylococcus aureus with two diffusion methods in agar medium and microdilution test). This research was conducted in a completely randomized design and SPSS and EXCEL softwares were used for statistical analysis and drawing of diagram, respectively. Data were analyzed by one-way analysis of variance and the difference between the means was evaluated by Duncan's test at 95% confidence level. Results and Discussion: The results showed that the average particle sizein different treatments with each other are significantly different (P<0.05) and vary from about 110 to 327nm; Also as the amount of chitosan in the coating increased, the particle size increased (P<0.05). This indicates the successful binding of chitosan to the surface of the nanoliposome, which results in the formation of a layer around the nanoliposome and an increase in particle size. Particle dispersity index was recorded less than 0.3 in all treatments and was not related to the amount of chitosan in the coating. With increasing the amount of chitosan in the coating of nanoliposomes, zeta potential increased significantly (P<0.05). This index changed from -55.34 in NN treatment to 53.14 mV in NN-CH (0.5) treatment. In fact, chitosan as a cationic polysaccharide changes the potential to positive values. As the amount of chitosan in coating of nanoliposomes increased, the encapsulation efficiency increased significantly in the treatments (P<0.05); this index increased from 32.19% in NN treatment to 75.14% in NN-CH (0.5) treatment. The results of the antibacterial activity of nisin in two methods of diffusion in agar medium and microdilution test showed that its antibacterial activity increased with nanoencapsulation of nisin with (and without) chitosan coating (p<0.05). Also, with the increase in chitosan concentration, the antibacterial activity of carrier nanoliposomes increased and the highest antibacterial activity was recorded in NN-CH (0.5) treatment (p<0.05). The diameter of the non-growth halo of Bacillus cereus against the research treatments (with five concentrations of 2.5 to 25 μg/ml) varied from about 4.5 to 17.5 mm. This amount for Staphylococcus aureus was recorded from 2.1 to 26.5 mm. By increasing the concentration of nisin and carrier nanoliposomes, the diameter of the halo of non-growth of both bacteria increased significantly (p<0.05). But an exception was recorded in this case; The diameter of the non-growth halo for Staphylococcus aureus in two concentrations of 2.5 and 5 μg/ml of treatments was the same and had no significant difference (p>0.05). The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the examined treatments for Bacillus cereus were in the range of 100 to 400 and 200 to 500 μg/ml, respectively. These two concentrations for Staphylococcus aureus were recorded as 50 to 200 and 100 to 400 μg/ml respectively. Based on the values of diameter of non-growth halo, MIC and MBC it can be claimed that Bacillus cereus is more resistant to the examined treatments than Staphylococcus aureus.Nanoencapsulation of nisin in the form of carrier nanoliposomes with chitosan coating is a suitable solution to improve its physical and antibacterial properties. In such a way that by increasing the concentration of chitosan in the coating, both of the aforementioned properties improved significantly. Nanoliposomes carrying nisin with (and without) chitosan coating have the ability to inhibit the growth and killing Bacillus cereus and Staphylococcus aureus bacteria. The antibacterial activity increases with the increase in nisin and carrier nanoliposomes concentrations. The value of non-growth halo, minimum inhibitory concentration and minimum bactericidal concentration confirm that Bacillus cereus is more resistant to nisin and its carrier nanoliposomes than Staphylococcus aureus.
Food Technology
Soheyl Reyhani Poul; Sakineh Yeganeh
Abstract
Introduction: Shrimps are highly sensitive to oxidation at refrigerator temperature. On the other hand, storage of shrimp in freezing conditions leads to a decrease in product quality after thawing. It should be noted that shrimp oxidation also occurs in freezing conditions, but the oxidation rate in ...
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Introduction: Shrimps are highly sensitive to oxidation at refrigerator temperature. On the other hand, storage of shrimp in freezing conditions leads to a decrease in product quality after thawing. It should be noted that shrimp oxidation also occurs in freezing conditions, but the oxidation rate in these conditions is much slower than storage in refrigerated conditions. Therefore, it seems necessary to use a method that can control the oxidation of shrimp in both freezing and refrigerating conditions. The aim of this study was to evaluate the feasibility of controlling shrimp oxidation (at refrigerator temperature) using whey protein coating containing ascorbic acid or α-tocopherol, and to compare the efficacy of these antioxidants (in combination with whey protein). Materials and Methods: In order to advance the purpose of the research, shrimp fillets were stored in four treatments, including treatments No. 1 (control), 2 (shrimp fillet coated by whey protein), 3 (shrimp fillet coated by whey protein + ascorbic acid) and 4 (shrimp fillet coated by whey protein+ α-tocopherol) at refrigerator temperature for 9 days. In order to evaluate the oxidation intensity and also the stability of the treatments against oxidative damage, peroxide indices, free fatty acids, anisidine and thiobarbituric acid of the treatments were determined on days 0, 3, 6 and 9. This study was implemented in form of completely randomized design and data were analyzed by one-way ANOVA. Significant differences among means were tested by Duncan's test at 95 confidence level. Results and Discussion: The results showed that whey protein alone (treatment 2) as shrimp coating can partially control the oxidation process of fillet fats compared to control. But when whey protein was combined with ascorbic acid (treatment 3) and α-tocopherol (treatment 4), the coatings' strength against oxidative deterioration significantly increased (p<0.05). According to our findings, during the storage period, the lowest amount of peroxide, free fatty acids, anisidine and thiobarbituric acid indices were related to treatment 3 (p<0.05). During the storage period, all the mentioned indicators (in all treatments) had an increasing trend, but the slope of this trend was different and the lowest slope was related to treatment 3. Comparison of fresh shrimp fillet fatty acid profile with fatty acid profile of treatments at day 9 showed that the whey protein coating combined with ascorbic acid (treatment 3) had the most protective effect on the structure of fatty acids. Overall, according to the results of the present study, it can be claimed that whey protein- ascorbic acid coating is more effective than whey protein-α-tocopherol coating to increase the oxidative stability of shrimp fillet. Therefore, the ascorbic acid is more efficacious than α -tocopherol (in combination with whey protein) in controlling the oxidation of shrimp fillets.
Soheyl Reyhani Poul; Seyed Ali Jafarpour
Abstract
Introduction: Following extensive research on antibacterial and antioxidant properties of chitosan and hydrolyzed proteins and their satisfactory results, the use of these compounds as natural preservatives and good alternative to antibacterials and synthetic antioxidants in various nutrients is essential. ...
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Introduction: Following extensive research on antibacterial and antioxidant properties of chitosan and hydrolyzed proteins and their satisfactory results, the use of these compounds as natural preservatives and good alternative to antibacterials and synthetic antioxidants in various nutrients is essential. The aim of the present study was to investigate the properties of chitosan coating containing FPH in the preservation of rainbow trout (Oncorhynchus mykiss) fillets at refrigerated temperatures. Materials and methods: The hydrolyzed protein powder (FPH) used in this study was produced by enzymatic hydrolysis of frame (skeleton with the meat attached to it) of common carp (Cyprinus carpio) with flavourzyme enzyme. Accordingly, this powder was added to the chitosan coating (2% w/v chitosan + 2% w/v FPH). In order to investigate antibacterial and antioxidant properties of chitosan coating containing FPH, rainbow trout fillets were coated with chitosan (treatment 2) and chitosan containing FPH (treatment 3). Then, these sample treatments and control (treatment 1) were subjected to chemical (PV, TVN-B, TBA, FFA and pH) and microbial (count of aerobic mesophilic and psychrophilic bacteria) tests on days 0, 4, 8, 12, 16 and 20 in refrigerated storage. This study was implemented in form of completely randomized design and data were analyzed by one-way ANOVA and significant differences between the means were tested by Duncan's test at 95 confidence level. Results and discussion: According to the chemical tests, TBA, TVN-B and FFA indices showed an increasing value during the refrigeration period significantly (P<0.05) while their trend was lower in treatment 3 compared to the treatments 1 and 2. TBA index for treatments 1, 2 and 3 in day 0 was 0.017, 0.015 and 0.014 mg MDA/kg fillet respectively that this amounts reached to 1.49, 0.99 and 0.52 mg MDA/kg in day 20. At the beginning of the preservation period, TVN-B index was calculated 13.36, 13.18 and 12.46 mgN/100gr fillet for treatments 1, 2 and 3, respectively. But these values changed to 43.36, 30.19 and 22.11 mgN/100gr fillet for mentioned treatments at the end of preservation period. FFA index was 0.16, 0.14 and 0.12 percentage of oleic acid for treatments 1, 2 and 3 in day 0 whereas after 20 days of storage, this index increased to 2.55, 1.76 and 0.98 percentage of oleic acid for mentioned treatments respectively. The PV index was significantly less in treatment 3 compared to the treatments 1 and 2 in days 12, 16 and 20 (2.72, 4.42 and 4.12 meq o2/kg lipid respectively) but continuous incremental trend was not recorded in this index with increasing preservation time, even the end of the experimental period (day 20), the index decreased in all of treatments compared to the 16th day. The results of pH changes showed the stability of this index in treatment 3 during the preservation period (pH~6.30). Meanwhile, in day 12, 16 and 20, the pH of treatment 3 was significantly less than treatments 1 and 2 (p<0.05). The bacterial load count of aerobic mesophilic and psychrophilic bacteria in treatments (while having an increasing trend during the preservation period) showed that in day 8, 12, 16 and 20, the bacterial levels of treatment 3 were significantly less than treatments 1 and 2 (p<0.05). In this study, adding FPH produced from common carp fish (with degree of hydrolysis 15.9%) to chitosan resulted in enhanced antioxidant and antibacterial properties of chitosan coating. So that, the film obtained from the combination of chitosan and FPH was much stronger barrier against lipids oxidation and bacterial proliferation in rainbow trout fillets (at refrigerated temperatures) than pure chitosan film.
Soheyl Reyhani Poul; Seyed Ali Jafapour; Reza Safari
Abstract
Introduction: With the growing population and following the efforts of food production industries, more waste is produced which can be recovered by adding value and brought them back into the cycle of production and consumption. The reason behind is firstly the reduction of waste and secondly the economic ...
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Introduction: With the growing population and following the efforts of food production industries, more waste is produced which can be recovered by adding value and brought them back into the cycle of production and consumption. The reason behind is firstly the reduction of waste and secondly the economic importance of value added resultant products. Aquaculture sector produces large volume of wastes including the head, tail, fins, spine, and most importantly their viscera. If the waste managed properly, valuable materials such as hydrolyzed protein powder (the resulting waste hydrolysis using proteases enzymes) and fish oil (byproduct of enzymatic hydrolysis) can be produced. In this study rainbow trout waste was chosen, due to its large volume production in the country. The functional properties and antioxidant activity of hydrolysates as well as the oil fatty acid profile are the main factors to be considered. This study was aimed to investigate the hydrolysis of rainbow trout viscera (oncorhynchus mykiss) by protamex and neutrase enzymes individually and compare the functional properties and antioxidants activity of protein hydrolysate as well as analyze the fatty acid profile of fish oil obtained as by-product of enzymatic hydrolysis process.
Materials and methods: Rainbow trout viscera (Oncorhynchus mykiss) were obtained from the fish market in Sari and transported in ice containers to the laboratory. Protamex and neutrase enzymes were purchased from Novozymes Company and protein hydrolysates prepared enzymatically according to the method of Guerard et al. (2002). Proximate analysis was carried out according to the procedures outlined by the AOAC (1995). Degree of hydrolysis determined as described by Hoyle and Merritt (1994). Peptide chain length (PCL) was measured using the method of Adler-Nissen and Olsen (1979). Protein recovery (PR) determined using the method used by Ovissipour et al (2009). Protein solubility for hydrolysates was determined using the method of Robinson and Hodgen (1940). Foam stability index was measured according to the method described by Sathe and Salunkhe (1981). Water holding capacity (WHC) was determined using the method of Rodriguez-Ambriz et al. (2005). DPPH radical-scavenging activity was measured using the method of Yen and Wu (1999). Reducing power was determined by the method of Oyaiza (1986).The chelating activity on Fe2+ was determined, using the method of Decker and Welch (1990).
Results & Discussion: Protamex leads to the production of protein powder with higher degree of hydrolysis (34.76 ± 2.92%) and protein recovery (68/16 ± 1.98%) compared to neutrase (p0.05) despite the difference in L* value. The viscera oil contains 34% monounsaturated, 34.49% polyunsaturated and 31.4% saturated fatty acid. Apart from pH 4 (isoelectric point), the solubility of both protein powders in water was remarkable (more than 90%). The foam activity and stability index of hydrolyzate produced by protamex were more desirable than hydrolyzate produced by neutrase, whereas at pH 6, these indices reached to their maximum values of 200.13± 9.31% and 135.6 ± 5.64 %, respectively. Furthermore, water holding capacity of both hydrolyzates was measured as approximately 4.5 ml/g protein (p>0.05). Protamex leads to the production of protein powder with the higher DPPH radical scavenging activity compared to hydrolyzate produced by neutrase. Conversely, the reducing power of hydrolyzate produced by neutrase was higher than that of protamex (p0.05).
