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1.
Utilization of shrimp head waste from the processing industry offers a solution to environmental pollution and also produces valuable bioactive peptides. The present study was aimed to optimize the alcalase assisted extraction conditions by response surface methodology (RSM) to obtain protein hydrolysates from shrimp (Metapenaeus dobsoni) head waste with maximum antioxidant activity. Based on the models derived by RSM, the optimized conditions for maximum degree of hydrolysis (DH) were pH 8.2, temperature of 45.4°C, and enzyme/substrate (E/S) of 1.8%. Meanwhile, the optimized conditions for maximum antioxidant activity of protein hydrolysates as measured by 2, 2-diphenyl-1-picrylhydrozyl (DPPH) and ferric reducing antioxidant power (FRAP) assays were pH 8.2 and 8.1, temperatures of 49.7 and 59.4°C, and E/S of 2.1 and 2.7%, respectively. The maximum predicted values for DH, DPPH, and FRAP were 42.44%, 39.64% inhibition, and 8.3 μM Fe (II)/g wet wt. of sample, respectively. The extraction of protein hydrolysates at optimal conditions derived by these models resulted in DH, DPPH, and FRAPs of 40.31%, 38.93%, and 8.21 μM Fe (II)/g of sample, respectively, demonstrating the fitness of the models. The present study demonstrates the potential of Metapenaeus dobsoni head waste as a source of protein hydrolysates with prospective antioxidant activity.  相似文献   

2.
ABSTRACT

In this study, the degreasing technology using alkaline lipase hydrolysis for Chinese dried shrimp (Acetes chinensis) was investigated, with the purpose of decreasing lipid oxidation during dried shrimp preservation. The salt, moisture, and lipid contents of the shrimp were 6.01, 32.51, and 2.95%, respectively. The optimum enzymatic hydrolysis condition for effective decrease of shrimp lipid was obtained: lipase concentration 40 U/mL, pH 10, soaking time 60 min, soaking temperature 30°C, and shrimp/liquid ratio 1:20 (w:v). Under this optimum condition, the residual lipid of the shrimp was reduced to 2.28%, and the degreasing rate reached 49%. During 30-day preservation, the thiobarbituric acid-reactive substances (TBARS) value (0.185 mg/kg of dried shrimp and 0.131 mg/kg of degreased dried shrimp at Day 30) of degreased shrimp was lower than the shrimp without degreasing, indicating alkaline lipase hydrolysis could effectively prevent lipid oxidation and inhibit oxidative rancidity during dried shrimp preservation.  相似文献   

3.
Total protease, trypsin and chymotrypsin activities were examined in postlarval Farfantepenaeus californiensis (Holmes) after they had been reared for 50 days at two dissolved oxygen concentrations (5.8 and 2.6 mg L−1) and three temperatures (19, 23 and 27 °C). Three replicated experiments were performed with a 12-h light/dark photoperiod. Two-way analysis of variance indicated a significant effect of temperature and oxygen (P < 0.05) on total protease and chymotrypsin activities, but no effect of oxygen was found on trypsin activity. A tendency towards increased protease, trypsin and chymotrypsin activities with acclimation temperature was observed. Total protease activity (units per mg protein) varied from 0.26 in shrimp held at 19 °C and low oxygen concentration to 1.41 in shrimp held at 23 °C and high oxygen concentration. Trypsin activity (units per mg protein) varied from 0.16 in shrimp held at 19 °C and low oxygen concentration to 0.86 in shrimp held at 27 °C and high oxygen concentration. Chymotrypsin activity (units per mg protein) varied from 0.014 in shrimp held at 19 °C and low oxygen concentration to 0.15 (units per mg protein) in shrimp held at 27 °C and low oxygen concentration. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) zymograms of hepatopancreas from each of the treatment groups showed numerous bands. The results suggest that different digestive protease enzymes arise as an adaptation mechanism to temperature and dissolved oxygen variations at this particular stage of life.  相似文献   

4.
Fishery by-products can be better utilized following enzymatic hydrolysis treatment to produce fish protein hydrolysates (FPH) with potentially enhanced interface-stabilizing properties (e.g. functionality). The production of FPH could be accelerated through the application of rapid heating methods [e.g. microwave-assisted heating (MW)] rather than slower conventional heating (CH) treatments. The objective of this study was to investigate the effects of microwave heating during enzymatic hydrolysis on the functionality and antioxidant properties of FPH. Trout by-products were hydrolyzed with Alcalase at an enzyme substrate ratio (E:S) of 0.5, 1.7, and 3.0% (w/v), respectively, for 3, 5 and 15 min using a microwave system (1200 W, 20% power with 50% duty cycle at 50–55 °C) and a conventional heating method (water bath at 50 °C). The degree of hydrolysis and protein solubility was higher (P < 0.05) for the MW-FPH than for the CH-FPH. MW-FPH at 5 min (0.5% E:S) demonstrated higher (P < 0.05) emulsifying activity and emulsion stability than CH-FPH with the same treatment. Foam capacity and stability were also greater (P < 0.05) for MW-FPH samples that were treated 15 min by microwave-assisted heating (0.5% E:S) when compared to CH. Overall, MW-FPH exhibited higher (P < 0.05) 2,2-diphenyl-1-picryhydrazyl and ferric ion reducing capacity than CH-FPH. We therefore conclude that microwave-assisted hydrolysis is an alternative method to produce FPH with improved solubility, emulsifying activity, foaming properties and antioxidant activity.  相似文献   

5.
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6.
Acid silage of shellfish processing waste has been reported to be a good and economical technique to protect these biomasses from bacterial decomposition. Shrimp (Pandalus borealis) by-products contain some value-added nutrients for the aquaculture industry such as carotenoid pigments (mainly astaxanthin) and n − 3 polyunsaturated fatty acids. The aim of this work was to determine the effect of ensiling shrimp waste during a long period of time (more than 3 months) on some unstable components such as the astaxanthin forms (free, mono- and diesterified) and polyunsaturated fatty acids. Comparisons of astaxanthin forms and the fatty acid profiles were performed on defrosted shrimp waste and on a 14-week-old shrimp waste silage. No significant difference (P ≥ 0.05) in the total lipids extracted from the two forms of shrimp waste was observed. Nevertheless, a small quantity of the red pigment, presumably an astaxanthin portion, was observed to stay firmly bound to the shrimp carapace after the solvent extraction in shrimp waste compared to the full recovery obtained in ensiled shrimp waste. This may explain the significantly (P < 0.05) higher concentration of total astaxanthin (4.57 vs 3.99 mg/g) found in the crude oil extracted from shrimp waste silage. Higher percentages (P < 0.01) of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were found in esterified astaxanthin from shrimp waste silage (43.9% and 45.5%) in comparison with their shrimp waste (24.7% and 20.3%) counterparts. This suggests that EPA and DHA are the principal fatty acids esterified with the portion of astaxanthin linked to chitin in the shrimp carapace. The utilization of shrimp waste silage as a pigmenting component of salmonid feeds is also discussed.  相似文献   

7.
内源酶辅助提取虾壳虾青素的研究   总被引：1，自引：0，他引：1  
文章探讨了内源酶对虾青素提取效果的影响,并以高效液相色谱法（HPLC）测定样品中虾青素的质量浓度,研究了pH、温度和酶解时间这3个因素对虾青素提取效果的影响,采用正交试验进行优化,以虾壳虾青素的萃取率作为评价提取效果的指标。结果表明,当酶解最佳工艺条件为pH 4.0,温度50℃,酶解时间1.5 h时,虾青素的萃取率最高,可达32.16μg.g-1湿虾壳,比直接超声提取提高28%。通过空白试验可知,外加脂肪酶对虾青素提取无促进作用,仅利用内源酶即可达到较好的提取效果,且经济节约。  相似文献   

8.
To investigate the setting condition of the gel-forming ability of rohu, optimum setting temperature for strong and weak gels of unwashed and washed rohu gel and optimum setting time for maximum proteolytic activity were investigated. Nine setting temperatures were studied for textural properties and trichloroacetic acid (TCA)-soluble peptide contents. Both unwashed gel (UW-gel) and washed gel (W-gel) showed similar optimum setting conditions for producing a strong gel that was set at 40°C for 30 min, followed by heating at 90°C for 20 min. They displayed different optimum setting conditions for weak gel. Weak gel from the degradation of UW-gel and W-gel formed at 65 and 60°C, respectively. The occurrence of protein degradation of W-gels during setting at 60°C suggested that washing did not remove the endogenous protease, and the degradation of unwashed and washed mince was due to water-soluble protease and myofibril-bound protease, respectively. Eight setting times for maximum proteolytic activity were shown by the TCA-soluble peptide contents, accompanying the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern. Both gels had similar results for setting for 120 min.  相似文献   

9.
The traditional procedure for chitosan production involves use of a strong acid (HCl) for demineralization of chitin. This study reports application of a mixed culture of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus acidophilus, and Lactobacillus lactis) fermentation in demineralization of chitin for chitosan production from shrimp waste. Chitosan produced from shrimp waste with lactic acid bacteria fermentation at 30°C for 72 h or 1 M lactic acid treatment at room temperature for 2 h followed by alkaline treatments (0.5 M NaOH at 25°C for 4 h followed by 12.5 M NaOH at 70°C for 10 h) contained very low protein (0.8–1.1%) and ash (<0.01%) contents with the same solubility (100%) as those of chitosan produced with hydrochloric acid treatment. Lactic acid bacteria fermentation and lactic acid treatment may be utilized in chitosan production from shrimp waste to reduce use of strong chemicals.  相似文献   

10.
ABSTRACT

The aim of the present study was to evaluate the feasibility of increasing lipid extraction in tilapia (Oreochromis niloticus) waste using different enzymes and to minimize the periods of hydrolysis to evaluate the performance of the lipid fractions. When processing waste tilapia, commercial enzymes were added that were composed of neutrase and alcalase acting at different hydrolysis times to produce the best yields. The treatment proved feasible for obtaining the protein hydrolysates. The type of enzyme and the hydrolysis time determined the degree of fractionation. The enzymes performed well, and the highest efficiency occurred within 2 h of hydrolysis. By fractionating, the obtained by-products can be applied in the preparation of feed, as the lipid fraction treatments yielded significant amounts of polyunsaturated fats and suitable n-6/n-3 ratios.  相似文献   

11.
ABSTRACT

Response surface methodology was used to investigate the effect of ultrasound-assisted extraction conditions including solvent:seaweed ratio (10:1–30:1), extraction temperature (30–50°C), and extraction time (30–60 min) on the total phenolic compounds and antioxidant activity of red seaweed (Laurencia obtuse) extracts. The optimum extraction parameters for maximum phenolic content were as follows: solvent:seaweed ratio, 30:1; extraction temperature, 50°C; and extraction time, 42.8 min. The experiment results showed that the solvent:seaweed ratio was the most significant parameter for the extraction. The optimum extraction conditions for maximum antioxidant activity were as follows: solvent:seaweed ratio, 24.3:1; extraction temperature, 45.3°C; and extraction time, 58 min. Under the above-mentioned conditions, the experimental total phenolic content and antioxidant activity value were 26.23 ± 0.75 mg GAE/g seaweed and 120.89 ± 0.81 TEAC, respectively, of seaweed tested, which are well compatible with the predicted contents.  相似文献   

12.
Method for determining the physical stability of shrimp feeds in water   总被引：4，自引：0，他引：4  
Three methods for measuring the water stability and leaching characteristics of shrimp pelleted feeds were developed and tested: static water method, horizontal shaking method and vertical shaking method. Each method was tested using a commercial and experimental pelleted shrimp feed. Both feeds had a pellet size of 2.4 mm × 5.0 mm with similar proximate composition (35% protein and 9% fat). Each test run consisted of leaching c. 2 g of feed at six intervals of immersion time (0, 30, 60, 120, 240, 360 min), two concentrations of salinity (0, 34 ppt), and three different water temperatures (15, 25, 35 °C). A refrigerated circulating water bath was used to maintain the desired level of water temperature. For the static water and horizontal shaking methods, a Buchner filtration apparatus with Whatman filter paper no. 3 (5 μ) was used to separate the remaining pellets from leached water. The vertical shaking method (VanKel) utilized a perforated stainless‐steel basket (381 μ) for leaching and serving as a filter to separate pellets from leached water. For all three methods, the leached feed and original feed samples were dried in a convection oven at 105 °C for 24 h and then cooled in a desiccator. Dried feed samples were weighed and analysed for dry matter retention. Pellet stability was calculated as the ratio of dry matter retention after leaching and dry matter of original samples expressed as a percentage. Results indicated that any method for pellet stability analysis should take into account water temperature and salinity in addition to actual pellet agitation rate to obtain accurate and consistent measurement of pellet disintegration and nutrient leaching. Dry matter retention was different for each shrimp feed with experimental feed (72.8%) showing lower retention than commercial feed (88%) after 6 h of VanKel leaching under normal shrimp culture conditions. The three methods provided reproducible results with both horizontal and vertical shaking methods recommended for routine laboratory analysis because they could provide different degrees of pellet agitation that simulate actual indoor and outdoor shrimp culture conditions.  相似文献   

13.
Persian Gulf cuttlefish mantles were hydrolyzed (CPH) using alcalase, and the optimal hydrolysis parameters were obtained for the highest degree of hydrolysis (DH) and strongest antioxidant (based on their ability to quench 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals) activity using response surface methodology (RSM). The predicted optimal parameters of DH and quenching DPPH radicals was: pH of 7.88, 50.2°C, 150 min, and enzyme to substrate ratio of 1.5%. The reducing power (RP) and ability of optimized peptides to quench ABTS radicals in a gastro-intestinal track model system increased during the intestinal stage, while scavenging ability against DPPH radicals dropped (P < 0.05). The oxidation of lipid was retarded in a lecithin-liposome model added with optimized CPH in a concentration dependent response. Ultrafiltration of optimized CPH showed that the 3–10 KDa fraction had the greatest DPPH radical scavenging activity, the 10–30 KDa fraction had the highest reducing power, and the <3 KDa fraction had the greatest ABTS radical scavenging activity.  相似文献   

14.
This research work evaluates the impact of 1.2% pomegranate peel extract (Pp) (Punica granatum), 0.1% grapefruit seed (Gfs) (Citrus paradisi) extract, and synthetic preservative 1.25% sodium bisulfite on shelf life extension of Litopenaeus vannamei stored at 4 and 15°C. The application of isothermal titration calorimetry (ITC) for comparison of the extracts and chemical preservative on shrimp quality retention based on the overall heat production by microbial and enzymatic degradation was addressed. The occurrence of probable bioactive responsible for antimicrobial and antioxidant activity components in the extracts was examined through gas chromatography-mass spectrometry (GCMS). At 4°C, Pp-treated shrimps resulted in 6.73 logCFU/g, 6.93 logCFU/g, 5.31 mgN/100 g, and 0.58 mgMDA/kg for aerobic plate count, psychrotrophic bacterial count, trimethylamine, and thiobarbituric-acid reactive substance, respectively, on the 15th day. At 15°C, Pp-coated shrimps retained quality until day 4. Isothermal calorimetric analysis resulted in a rapid and sharp peak for fresh samples, whereas there was broad and delayed peak for shrimp treated with Pp and sodium bisulfite. These observations prove that Pp counterpart the chemical preservative and outperform Gfs on shrimp quality retention. Results also indicate that isothermal calorimetry can be a useful technique for shelf life predictions and comparative evaluation of extract impact on shrimp quality retention.  相似文献   

15.
This study was performed to determine the growth and survival patterns of the juvenile yellowleg shrimp Farfantepenaeus californiensis cohabiting with the green feather alga Caulerpa sertularioides over a range of temperatures (18, 22, 25, 28 and 32°C) found throughout the year in the Gulf of California. From an initial weight of 46 ± 10 mg, shrimp cohabiting with green feather algae increased in weight by an average of 0.57 (±0.07), 5.44 (±0.45), 6.36 (±0.37), 7.66 (±0.26) and 5.96 (±0.59) g at 18, 22, 25, 28 and 32°C, respectively, whereas shrimp grown without seaweed increased in weight by an average of 0.28 (±0.026), 2.66 (±0.24), 3.15 (±0.49), 4.00 (±0.67), and 3.54 (±0.09) g respectively. Statistically significant differences were observed for the growth rates of juvenile yellowleg shrimp in the presence of C. sertularioides and peak growth was observed at 28°C in experiments with macroalgae. No significant differences were observed for shrimp survival except at 32°C without macroalgae, where survival was lower. These results suggest a beneficial and growth‐promoting effect of cohabitation with live C. sertularioides on F. californiensis.  相似文献   

16.
Digestive alkaline proteinases from golden grey mullet (Liza aurata) were extracted and characterized. The crude alkaline protease showed optimum activity at pH 8.0 and 60°C, and it was highly stable over a wide range of pH from 4.0 to 10.0, retaining more than 80% activity after incubation for 1 h at 4°C. The alkaline proteases showed extreme stability toward nonionic and anionic surfactants after preincubation for 1 h at 25°C and relative stability toward oxidizing agents. Additionally, the crude enzyme showed excellent stability and compatibility with various solid and liquid detergents. Further, proteases from golden grey mullet viscera were found to be effective in the deproteinization of shrimp wastes. The protein removal after 3 h at 45°C with an enzyme/substrate (E/S) ratio of 10 U/mg protein was about 76%. The golden grey mullet proteases were also shown to be efficient in the production of antioxidant protein hydrolysate.  相似文献   

17.
The diet of frozen grass shrimp (P. varians) was compared to similar grass shrimp that had suffered either boiling, drying at 60°C, or freeze-drying by lyophilization at −40°C. In experiment 1, cuttlefish fed the frozen shrimp were significantly larger (P < 0.05) at the end of 10 days and at the end of the experiment, compared with those fed the boiled or dried shrimp. Growth rates were also higher for cuttlefish fed the frozen shrimp, compared with the remaining two. Growth rates were also higher for cuttlefish fed the frozen shrimp, compared with the remaining two. In experiment 2, there were no differences in weight (P > 0.05) between cuttlefish fed the frozen or the freeze-dried shrimp, whereas cuttlefish fed the dried shrimp were smaller at the end of the experiment. Growth rates of cuttlefish fed the dried shrimp were lower, compared with those for cuttlefish fed the frozen and freeze-dried shrimp, with no significant differences (P > 0.05) between them. Cuttlefish fed freeze-dried and frozen shrimp showed a higher trypsin activity compared to animals fed boiled and dry (60°C) shrimp. A higher proportion of absorbed energy was channelled into biomass production in animals fed frozen and freeze-dried shrimp (56% and 43%, respectively) than for animals fed oven-dried (60°C) or boiled shrimp. The heat treatment suffered by the shrimp, either dry or wet, negatively affected diet quality, probably due to denaturation, and loss (by boiling) of proteins and amino acids. Additionally, the heating processes may have oxidized the lipids to a large extent, contributing to the loss of the polar lipids (polyunsaturated fatty acids), which are essential for cephalopods as for other organisms. Freeze-drying by lyophilization (negative temperatures) did not affect the nutritional quality of the shrimp.  相似文献   

18.
Chemical composition and physical properties of 11 salted shrimp pastes (Kapi) obtained from various places of Thailand were determined. Based on proximate composition, protein constituted the major component (29.44–53.27 %, dry wt. basis). All samples contained 22.77–35.47 % NaCl with A w of 0.695–0.774. Various formal nitrogen contents (11.96–22.87 mg N/g sample) were in agreement with different degrees of hydrolysis (12.68–20.76 %), suggesting the varying cleavage of peptides among the samples. From electrophoretic study, salted shrimp paste contained a large amount of small molecular weight proteins and peptides. Different samples had different colors with \( \Delta E^{*} \) of 47.10–60.43 and \( \Delta C^{*} \) of 9.46–20.76. The samples had total carotenoid content of 0.54–1.97 mg/g sample. Free astaxanthin, astaxanthin diester and canthaxanthin were the major carotenoids in salted shrimp paste. Thus, salted shrimp paste is a good source of protein and serves as the nutritious condiment.  相似文献   

19.
The kinetics of astaxanthin degradation and lipid oxidation in shrimp oil from hepatopancreas of Pacific white shrimp (Litopenaeus vannamei) as affected by storage temperature were studied. When shrimp oil was incubated at different temperatures (4, 30, 45 and 60 °C) for 16 h, the rate constants (k) of astaxanthin degradation and lipid oxidation in shrimp oil increased with increasing temperatures (p < 0.05). Thus, astaxanthin degradation and lipid oxidation in shrimp oil were augmented at high temperature. When shrimp oils with different storage conditions (illumination, oxygen availability and temperature) were stored for up to 40 days, astaxanthin contents in all samples decreased throughout storage (p < 0.05). All factors were able to enhance astaxanthin degradation during 40 days of storage. With increasing storage time, the progressive formation of primary and secondary oxidation products were found in all samples as evidenced by the increases in both peroxide values (PV) and thiobarbituric acid reactive substances (TBARS) (p < 0.05). Light, air and temperatures therefore had the marked effect on astaxanthin degradation and lipid oxidation in shrimp oils during the extended storage.  相似文献   

20.
Acute toxicity and anesthetic effects of clove oil were studied in P. semisulcatus (1.8–2.1 g body weight). The EC50 1-h (the concentration effective for 50% of test animals), LC50 1-h (the concentration lethal to 50% of test animals after 1 h) and LC50 24-h (the concentration lethal to 50% of test animals after 24 h) were calculated at concentrations of 25, 130 and 30 mg/l, respectively, at 30°C, salinity 40 ppt, pH 8.6 and dissolved oxygen >6 mg/l. Generally, with increasing concentrations of clove oil, the times required for sedation and anesthesia decreased, while the recovery times increased. At concentrations 50, 100, 150 and 200 mg/l under temperature of 30°C and salinity of 40 ppt, the times required for sedation were 6 ± 0.2, 2.5 ± 0.3, 2 ± 0.08 and 0.5 ± 0.08 min, while times required for complete recovery were calculated to be 4.5 ± 0.3, 5.5 ± 0.17, 6.5 ± 0.25 and 11 ± 0.38 min, respectively. Also, the times required for deep anesthesia were 20 ± 1, 5 ± 0.5, 3 ± 0.4 and 2.2 ± 0.5 min in the above concentrations, while the times required for complete recovery were 10 ± 1, 11 ± 1.5, 14 ± 2.2 and 16 ± 3 min, respectively. Furthermore, considering the times to sedation, deep anesthesia and recovery at different temperatures of 20°C, 25°C, 30°C and 35°C and salinities of 25, 30, 35, 40 and 48 ppt; the combinations of salinity plus temperature and clove oil concentration plus salinity had the greatest and the least effects.  相似文献   

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