Purification of alkaline protease from chicken intestine by aqueous two phase system of polyethylene glycol and sodium citrate.

An aqueous two phase system of polyethylene glycol (PEG) and salts was evaluated for separation and purification of alkaline proteases from chicken intestine. Among the different salts evaluated potassium phosphate and sodium citrate gave higher enzyme yield (73.5% and 69.7% respectively) and enzyme purification (5.3 and 7.4 fold) in PEG rich upper phase. Increase in concentration of sodium citrate in the system resulted in reduction in enzyme yield and enzyme purification factor, with 15% salt showing highest enzyme yield (59.8%) and purification (6.7 fold). Initial protein concentration in the system did not show any specific trend on the partition behavior of the enzyme. The temperature at which the system is incubated did not show any significant (p ≥ 0.05) effect on enzyme partition and purification. Increasing the PEG concentration in the system from 15 to 25% resulted in reduction in enzyme yield from 53.7 to 21.9% and enzyme purification from 5 fold to 1.4 fold in PEG rich upper phase. pH also had a significant (p < 0.05) effect on the partition of the enzyme to the upper phase with highest purification (3.4 fold) at pH 9.0 and higher enzyme yield (46.2%) at pH 10.

Utilization of tannery fleshings: Optimization of conditions for fermenting delimed tannery fleshings using Enterococcus faecium HAB01 by response surface methodology.

Conditions for fermentation of delimed tannery fleshings--to obtain higher degree of protein hydrolysis and reasonably better antioxidant activity--using Enterococcus faecium HAB01 (GenBank #FJ418568) were optimized. Three independent variables--viz., inoculum level (X1), glucose level (X2) and fermentation time (X3)--were optimized using response surface method considering degree of hydrolysis (DH; %) and total titrable acidity (TTA) as response variables. The optimized conditions were found to be 12.5% (v/w) inoculum, 17.5% (w/w) glucose and 96h of fermentation at 37+/-1 degrees C to obtain a maximum DH%. The usefulness of the predicted model was further validated by considering random combinations of the independent factors. The chemical score of the hydrolysate revealed an excess amount of essential amino acids, viz., arginine and leucine compared to reference protein. The liquor portion had relatively high antioxidant activities, indicating its potential for use as a high value feed ingredient.

Stability of carotenoids recovered from shrimp waste and their use as colorant in fish sausage.

The stability of carotenoids recovered from shrimp waste using organic solvents and vegetable oils as affected by antioxidants and pigment carriers was evaluated during storage under different conditions. Solvent extracted carotenoid incorporated into alginate and starch as carriers was stored in metallised polyester and polypropylene pouches. Oil extracted carotenoids were stored in transparent and amber bottles. Also the use of recovered pigments as colorants in fish sausage was evaluated. Antioxidants, packaging material and storage period had a significant effect (p≤0.001) on the reduction of carotenoid content, while type of carrier had marginal effect (p≥0.05) on solvent extracted carotenoids during storage. Carotenoid content in pigmented oil was significantly affected by antioxidants (p≤0.001), packaging material (p≤0.05) and storage period (p≤0.001). Addition of carotenoid to the sausage enhanced the sensory colour, flavour and overall quality score of sausage and the added carotenoid was stable during processing.

Effect of ensiling and organic solvents treatment on proteolytic enzymes of layer chicken intestine.

Effect of ensiling and organic solvents on the protein extractability and on the activities of the proteolytic enzymes of layer chicken intestine was evaluated. The protein content of water extract of layer chicken intestine was 2.45 mg/ml. Highest proteolytic activity (26.3 units) was observed at pH 10.6 and lowest at pH 6.8 (7.2 units). Higher acidic proteolytic activities were observed at pH 2.4, pH2.8 and at pH 5. Acid ensiling resulted in 65.6% reduction in acidic protease activity compared to 57.4% reduction by fermentation ensiling. Neutral and alkaline protease activities were also reduced up to a maximum of 41.8% and 46.5%, respectively. A ratio of 1:1.5 of cold acetone to intestine homogenate was found best for enhancing the neutral and alkaline protease activity. The study revealed that layer chicken intestine is a rich source of proteases especially of neutral and alkaline proteases, which could be harvested for commercial purposes and both acid and fermentation ensiling of layer chicken intestine resulted in reduction of protein extractability and enzyme activity. Treatment with acetone almost doubled the activities of neutral and alkaline proteases compared to initial values in water extract of fresh intestines.

Characterization and application of a native lactic acid bacterium isolated from tannery fleshings for fermentative bioconversion of tannery fleshings.

Lactic acid bacteria (LAB) species isolated from limed and delimed tannery fleshings (TF) were evaluated for their fermentation efficiency and antibacterial property. The native LAB isolates efficiently fermented TF and resulted in a fermented mass with antioxidant properties, indicating their potential for effective eco-friendly bioconversion of TF. From among the LAB isolated, a proteolytic isolate showing better antimicrobial spectrum and reasonably good fermentation efficiency was identified as Enterococcus faecium HAB01 based on various biochemical and molecular tests. This isolate afforded a better degree of hydrolysis (81.36%) of TF than Pediococcus acidilactici (54.64%) that was previously reported by us. The bacteriocin produced by E. faecium was found to be antagonistic to several human pathogens including Listeria, Aeromonas, Staphylococcus and Salmonella. Further, E. faecium HAB01 bacteriocin was thermostable and had a molecular weight of around 5 kDa, apart from being stable at both acidic and alkaline conditions. The bacteriocin was unstable against proteases.

Protein hydrolysate from visceral waste proteins of Catla (Catla catla): optimization of hydrolysis conditions for a commercial neutral protease.

Protein hydrolysate was prepared from visceral waste proteins of an Indian freshwater major carp, Catla catla. Hydrolysis conditions (viz., time, temperature and enzyme to substrate level) for preparing protein hydrolysates from the fish visceral waste proteins using in situ pH of the visceral mass were optimized by response surface methodology (RSM) by employing a factorial design. The regression coefficient close to 1.0, observed during both experimental and validation runs, indicated the validity of prediction model. An enzyme to substrate level of 1.25 % (v/w), temperature of 55 degrees C and a hydrolysis time of 165 min were found to be the optimum conditions to obtain a higher degree of hydrolysis of >48% using multifect-neutral. The amino acid composition of the protein hydrolysate prepared using the optimized conditions revealed that the protein hydrolysate was similar to FAO/WHO reference protein. The chemical scores computed indicated methionine to be the most limiting amino acid. The protein hydrolysate has the potential for application as an ingredient in balanced fish diets.

Recovery of carotenoids from shrimp waste in organic solvents.

Shrimp waste, which is produced in large quantities in the Indian seafood processing industries, is one of the important sources of natural carotenoids. Studies were carried out to assess the extractability of shrimp waste carotenoids in different organic solvents and solvent mixtures and to optimize the extraction conditions for maximum yield. A 50:50 mixture of isopropyl alcohol and hexane gave the highest (43.9 microg/g waste) carotenoid extraction yield compared to acetone, methanol, ethanol, isopropyl alcohol, ethyl acetate, ethyl methyl ketone, petroleum ether, and hexane individually and to a mixture of acetone and hexane. Extraction conditions such as percentage of hexane in the solvent mixture of isopropyl alcohol and hexane, ratio of solvent to waste and number of extractions was optimized using a statistically designed experiment. The optimized conditions for maximum yield of carotenoids were 60% hexane in solvent mixture, solvent mixture to waste ratio of 5:1 in each extraction and three extractions. A regression equation for predicting the carotenoid yield as a function of three processing variable (hexane % in solvent mixture, solvent-to-waste ratio and number of extractions) was derived by statistical analysis, and a model with predictive ability of 0.98 was obtained.

Process optimization for extraction of carotenoids from shrimp waste with vegetable oils.

Shrimp waste is an important source of natural carotenoid. Studies were carried out to determine the extraction yield of shrimp waste carotenoids in different vegetable oils. Highest yield was obtained by extraction using refined sunflower oil compared to groundnut oil, gingelly oil, mustard oil, soy oil, coconut oil and rice bran oil. The extraction yield of carotenoids in sunflower oil was significantly influenced by level of oil to waste (p < 0.05), time (p < 0.01) and temperature (p < 0.001) of heating waste with oil before centrifugation to separate pigmented oil. A regression equation was derived for carotenoid yield as a function of time of heating, temperature of heating and oil level to waste. The optimized conditions for extraction of shrimp waste carotenoids in sunflower oil were determined to be oil level to waste of 2, temperature of 70 degrees C and heating time of 150 min.

Quality of buffalo meat burger containing legume flours as binders.

The effect of addition of different decorticated legume flours, viz., soya bean, bengal gram, green gram and black gram, on the quality of buffalo meat burger was studied. The burgers consisted of optimized quantities of roasted or unroasted legume flour, spices and common salt. Inclusion of roasted black gram flour registered the highest yield of 95.7%, lowest shrinkage of 5% and lowest fat absorption of 26.6% on frying. Protein content of 18-20% was highest in the soya flour formulation. Free fatty acid (FFA) values (as% oleic) increased from 14.3 to 17.3 in freshly prepared samples (before frying) to 16.0-19.4 in 4 m frozen (-16±2 °C) stored samples and fried samples had about 25% lower FFA values. Formulations with roasted flours registered lower thiobarbituric acid (TBA) values (mg malonaldehyde/kg sample) of 0.6-1.5 as against 0.6-2.1 for unroasted flours before frying. The burgers prepared with any of these binders were organoleptically acceptable even after storage at -16±2 °C for 4 months., However, the burger with black gram dhal (dehulled split legume) flour had better sensory quality attributes compared to other legumes.

Utilization of fermented silkworm pupae silage in feed for carps.

Fermented silkworm pupae (SWP) silage or untreated fresh SWP pastes were incorporated in carp feed formulations replacing fishmeal. The feed formulations were isonitrogenous (30.2-30.9% protein) and isocaloric (ME = 2905-2935 kcal/kg). Feeding under a polyculture system consisting of 30% each of catla (Catla catla), mrigal (Cirrhinus mrigala) and rohu (Labeo rohita) with 10% silver carps (Hypophthalmychthys molitrix) was carried out in ponds to evaluate the nutritive quality of SWP silage. Survival rate, feed conversion ratio and specific growth rate, respectively, were 84.2%, 2.10 and 2.39 for fermented SWP silage, 65.8%, 2.98 and 2.26 for untreated SWP and 67.5%, 3.16 and 2.20 for fishmeal indicating clearly that the fermented SWP silage was nutritionally superior to untreated SWP or fishmeal. The dietary influence on the proximate composition of whole fish was marginal.

Influence of direct and delayed chilling of excised female buffalo muscles on their textural quality.

The excised muscles from the left half of 6 carcasses of old female buffaloes (4-5 years of age) were held, soon after slaughter, at the temperature of 2-3°C for 24 h (direct chilling) and those from the right half at ambient temperature (26±2°C) up to 6 h postmortem followed by chilling at 2-3°C for 18 h (delayed chilling) in order to study the improvement in the texture quality of muscles. During the delayed chilling, the muscle pH decreased to 6.0 (from the initial value of 6.5) in 3 h whereas it took 5-6 h in direct chilling. Reduction in Instron firmness values was 10.3-33.6% and that in cohesiveness values was 13.2-22.2% in delayed chilled muscles compared to direct chilled ones when cooked muscles were sheared along or across the muscle fibres. These observations were statistically significant (P⩽ 0.001) indicating a definite improvement in the texture quality of muscles subjected to delayed chilling. However, no definite trend was observed in the values of elasticity, cooking loss and water holding capacity of muscles due to direct or delayed chilling.

Observations on some chemical and physical characteristics of buffalo meat.

Proximate composition, sarcoplasmic and myofibrillar protein fractions of buffalo meat were similar to those of beef. Buffalo meat was also rich in lysine. Meat from young animals had a lower collagen content than that from old ones. As the temperature of holding the carcasses was increased, the rate of pH fall was faster. Meat from stressed animals showed a higher ultimate pH. Percentage of cooking loss and thermal shrinkage was higher in muscles of old animals than in young ones, which probably reflected the poor condition of the older animals. Meat cooked by pressure cooking showed lower Warner-Bratzler shear values as compared with meat cooked in boiling water.

Effect of freezing, thawing and frozen storage on physico-chemical and sensory characteristics of buffalo meat.

A study was conducted on some physico-chemical and sensory characteristics of buffalo meat frozen by plate and blast freezing and stored at -15 ± 3°C for a period of 3 months. A marginal increase in pH values and drip losses were observed during the storage period. Drip losses were less in blast frozen samples. WHC, cooking losses thermal shrinkage and WB Shear values indicated inconsistent results, during storage. Similar observations were recorded with regard to tyrosine and TBA values. No significant differences in the physico-chemical characteristics were observed between meat cuts and minced meat. Plate frozen meat samples scored higher for texture, juiciness and aroma. Both the plate and blast frozen meat samples, however, were similar in overall quality according to taste panel results.

Effect of post-mortem conditioning of ewe carcasses on instrumental texture profile of cooked thigh muscles.

The semimembranosus (SM) and semitendinosus (ST) muscles were removed from 18 four to five year old Bannur breed ewes which were slaughtered and carcasses (six each) suspended by the (a) Achilles tendon at 26 ± 2°C for 1 h before cutting (b) Achilles tendon at 2-3°C for 42 h and (c) Pelvis at 26 ± 2°C for 7 h followed by chilling at 2-3°C for 17 h. The muscles were cooked by boiling in a water bath for 30 min or by heating in a pressure cooker for 20 min and the tenderness measured with a Warner-Bratzler tenderometer. Hardness, cohensiveness, elasticity and chewiness were also measured with a General Foods Texturometer. With conventional hanging at 2-3°C the SM muscle was the toughest and the ST muscle the most tender. By holding carcasses at 26 ± °C for 1 h before cooking there was an increased tenderness. The most tender meat was found from carcasses which were suspended by the pelvis at 26 ± °C before chilling. The increase or decrease in shear values were respectively associated with contraction or stretching of muscles effected by carcass conditioning treatments. In contrast, thermal shrinkage due to cooking had opposite effects so that greater thermal shrinkage resulted in lower shear values. The shear values from the Warner-Bratzler tenderometer did not correlate well with the parameters measured by the General Foods Texturometer.

Effect of conditioning and carcass posture on eating quality of mutton from old Bannur ewes.

Twenty-six mature ewes of an indigenous mutton breed, slaughtered and dressed conventionally, were used for the experiment described in this paper. The effect of three different conditioning temperatures and two methods of hanging posture on texture and palatability were assessed on leg muscles. Corresponding muscles from freshly slaughtered ewes were used as a control. A significant reduction was brought about in shear force in SM and BF muscles by different treatment combinations as compared with the control. There was, however, little variation in cohesiveness between treated and untreated BF and ST muscles. Holding carcasses at 14-15°C for 24 h, followed by chilling at 4-5°C for 24 h with pelvic hanging reduced shear values to the optimal level, as validated by sensory tenderness/toughness. The sensory parameters showed a significant difference between pelvic and Achilles tendon hanging. In all treatments pelvic hanging tenderised meat to a significantly greater extent than did Achilles tendon hanging.