Abstract
▼
1. Development of shelling technique of abalone using high pressure processing
○ In general, separating shell, intestine or...
1. Development of shelling technique of abalone using high pressure processing
○ In general, separating shell, intestine organs and abalone muscle is manually processed. Shell is tightly attached with abalone muscle and easy to mishandled. In this study, we developed new technique to separate shell from muscle using high pressure processing.
○ Abalones were vacuum-packaged, immersed in water as well as organic acids and pressurized. Based on appearance, no changes in height of abalone was found after 100 MPa pressurization, while decrease in height was observed in abalone treated at > 200 MPa for 3 min. In particular, 50% decrease in height of abalone was shown when the abalone was pressurized at 500 MPa for 1 min.
○ When the abalone was filled into water and pressurized, holding time and pressure level were not attributed the appearance of abalone, and there was no significant difference in height of abalone treated at 500 MPa for 3 min with those treated at 100 MPa for 1 min.
○ The abalone filled into water and pressurized showed a decrease in thickness of the edge of abalone, while these phenomena were not found when the abalone was filled into organic acid and pressurized.
○ For total plate count (TPC), no changes in the TPC was shown in the balone treated at 100-200 MPa, while the microbial growth was not detected in the abalone pressurized at 300 MPa and 500 MPa.
○ When th abalone was filled with water, high pressure-mediated microbial inactivation was not noticeable. Meanwhile, replacement of organic acid with water had an effect to inactivate microbial growth even if high pressure was not applied.
2. Screening of proteases to produce low molecular weight (Mw) abalone-peptides
○ Proteases of which hydrolysis activity was greater at high pressure were explored by literatures and selected flavozyme, protamex, alcalase and neutrase.
○ Alcalase and Flavourzyme were diluted with water and 20 mM phosphate buffer (pH 7.0) and incubated at 50℃ and 100 MPa for 24 h to estimate enzyme activity. The enzyme activity of these proteases were 45-47% enev after pressurization for elongated holding time.
○ At the atmosperic condition, proteolytic activity of selected enzymes were Alcalase > Protamex > Flavourzyme > intrinsic abalone enzyme. Intrinsic abalone enzyme alone could not provide an impact of proteolysis, thus, addition of proteases were essential to obtain target molecular weight (Mw) peptides.
○ Based on the test of proteases, pH of hydrolysates was decreased during proteolysis, and the decrease was greater when the applied pressure level is higher. The results indicated that high pressure improved the proteolytic activity of tested enzymes.
○ Hydrolysates showed lighter color than that prior to hydrolysis, particularly, Protamex showed the best hydrolysis pattern under high pressure. The degree of hydrolysis was estimated by monitoring the production of low Mw peptide (< 1,300 Da).
○ Based on sensorial test, bitterness and off-flavor were involved in abalone hydrolyzed by selected proteases. To eliminate the off-flavor generation, abalone was eviscerated prior to protease treatment.
○ The amount of produced low Mw peptides were in the order of Flavourzyme, Protamex, Alcalase and Neutrase. However, the production ratio of low Mw peptides were Protamex > Alcalase > Neutrase . Flavourzyme. Therefore, protamex was effective protease to produce low Mw abalone peptide.
○ Bitterness was predicted by generation of tryptophan, and the tryptophan generation was in the order of Alcalase > Flavourzyme = mixed proteses (Alcalase: Flvourzyme=1:5) > protamex.
○ Based on the sensorial test, debittering effect was Protamex > mixed protease = Flavourzyme > Alcalase. Eventually, the debittering was better when protamex or mixed proteases were applied into abalone.
3. Isolation and fractionation process of low Mw peptide of abalone
○ Proteolitic efficiency of proteases were improved under pressure, for instant, about 65% was improved at 100 MPa. Recovery of solid content was affected by ratio of substrate. When the ratio of substrate was 50% (1:1), recovery of solid was around 55%, while the recovery was 65-70% when th ratio of substrate was 33% (1:2) and 25% (1:3) without significant difference.
○ Therefore 33% was best ratio of substrate when the processing efficiency was considered.
○ Volatile nitrogen content of peptide was not differ among treatments, while it slightly increased by addition of 1% intestinal organ content. Meanwhile, the increase of volatile nitrogen was greater when protamex or alcalase were concomitantly added.
○ Finally, pressure level (60-100 MPa) was regulated to evaluate the effect of pressure on the proteolytic efficiency. After 24 h of incubation, proteolytic activity was increased up to 60% by addition of flavourzyme at 60 MPa, 65% at 100 MPa and 67% by alcalcase treatment.
○ To develop isolation and fractionation process using a pilot-scale high pressure liquefaction processor, mixed enzyme (Alcalase: Flavourzyme: Protamex = 2:1:1) was applied.
○ Aftter shelling and evisceration, abalone muscle and water was mixed with 1:2 ratio and ground. 1% enzyme was added into the mixture and incubated at 50℃, 100 MPa for 24 h using a commercial high pressure system (working volume of 50 L). After pressurization, proteases were inactivated by heating th mixture at 95℃ for 10 min, and the mixture was cooled down at 4℃ for 24 h. The final hydrolysate was centrifuged, and the supernatant was fillterd through 5 kDa cut-off membrane followed by nanofiltration of 250 Da.
○ After filtration through 5 kDa cut-off membrane (primary filtration), retentate and permeate ratio was 24.4% and 75.6% respectively.
○ By nanofiltration (secondary filtration), retentate (N-1) and permeate ratio was 50% and 50%, respectively. Retentate ratio of nanofiltrate was twice higher than primary filtration.
○ Yield of fractions was in the order of hydrolysate (58.8%), U-1 (26.9%), N-1 (44.1%) and N-2 (8.7%). By converting th protein content basis, yield of fractions was in the order of hydrolysate (43.7%), U-1 (22.1%), N-1 (47.6%) and N-2 (7.9%).
○ Upon physicochemical analyses, pH of U-1 was lowest, while th pH of treatment was not significant.
○ Based on free amino acid contents, tryptophan and glutamic acid were highest in N-1 fraction. Therefore, it was expected that N-1 faction could be used as condiment.
○ Effective process is evaluated by continuous process of ultrfiltration and nanofiltration. Based on the results, procedure of low Mw peptide was established by :materials →washing→grinding and homogenization→packaging→hydrolysis under pressure→heat treatment→quick cooling→cold aging→defatting→centrifuge→fractionation and concentration.
○ Fractionated and isolated peptide were formulated by granule-type to stabilize during storage and distribution.
4. Development of beverage and powder using low Mw abalone peptide
○ Abalone was washed twice using a clean water and ground using a mexer.
○ Substrate ratio was abalone muscle:water = 1:2. Into the pouch, the substrate and 1% enzyme (Alcalase: Flavourzyme: Protamex = 2:1:1) were added.
○ The package with abalone substrate and enzyme was sealed and treated at 100 MPa/50℃ for 24 h. After high pressure liquefaction, the sample was chilled by 3℃/20 min which was effective to remove residual fatty.
○ The low Mw peptide was centrifuged at 10,000 rpm for 30 min, and the supernatant was filtered whereas the precipitate was dried(hot-air drying) and ground.
○ Into the fillted supernatant, 2% lemon juice and 3% trehalose were added and autoclaved at 121°C for 15 min.
○ Amino acid profiles of concentrated low Mw peptide showed that arginine and taurine were dominated. Yield of the concentrated peptide was 85% with high degree of hydrolysis. Precipitate accounted for 5% and the remaining 5% was loss during processing.
○ Based on sensorial test, 30 ml ample was best and the proce of the ample was estimated to 5,000 won.
○ For production of peptide powder, Mw of NF300 was < 300 Da, and easy to be spoilage due to high nutritional value. Therefore, spray dry is best way to produce peptide powder with maintaining the product quality.
○ However, direct spray-drying of NF300 caused sticky and film solid-form, hence excipien was required. The excipien and NF300 ratio of 1:1 was appropriate. After spray-drying, yield of powder was 10-11%.
○ To improve th yield of powder, various dextrin was mixed with the samples, and finally best yield was obtained when 5% dextrin was added.
5. Development of tenderized alabone product
○ The elders requires to take regularly healthy functional foods because their immune system become weak from the external environments when they are older.
○ In this study, abalone was immersed into protease solution to produce tenderized abalone products for silver food. Appearance of the test product was similar to normal abalone products while the tenderness of the product was improved.
○ Injection of protease solution was conducted by syringe needle. Protamex showed better tenderizing effect than pineapple extract. Proteolysis at atmosphere was best when 1% enzyme was added under 50℃ and 1 h incubation.
○ The tenderized abalone was cooked under the condition of 150C overheating for 2-8 min. Shear force of the product was not differ when the cooking time of 2-6 min while the texture was harden at 8 min treatment.
○ For test product, 20% soy sauce, 2% black pepper, 15% sucrose 10% wine, 13% butter and 40% water was formulated.
○ For package, Cryovac vacuum skin packer was used and final product price was established to 7,000 won.
6. Development of natural condiment using abalone hydrolysate
○ For natural condiment production, 15% intestine powder, 5% concentrated by-product, 20% low Mw peptide powder, 8% kelp powder, 6% garlic powder, 27% mushroom powder, 13% salt were formulated.
○ Product price was estimated to 12,250 won/100 g product, and final costomer price was 25,000 won/100 g. This estimated price was mormally similar to commercial naturl condiment.
7. Development of non-thermal pasteurization technique of abalone using high pressure processing
○ Estimated shelf-life of abalone is around 3 days under chilled storage condition, which limits chilled abalone distribution. In the present study, high pressure and hurdle technology were adopted to extend shelf-life of abalone.
○ To optimize the high pressure condition, response surface methodology (RSM) was adopted under varying pressure levels and holding times. The best condition where the shelf-life was maximum without quality deterioration was 230 MPa for 3 min. At higher than 230 MPa of pressure, changes in physicochemical properties of abalone were manifested, although shelf-life extension was possible.
○ To reduce the pressure level, abalone was washed with 2% citric acid followed by pressurization. Abalone washed and pressurized at 300 MPa was stored for 14 days under refrigerated temperature.
○ When the abalone was filled with citric acid/NaCl solution, moisture loss was caused which resulted in high shear force of final product.
○ For test product, HOCl could be replaced to citric acid washing, thus established processing of chilled abalone product was washing (HOCl)→vacuum packaging→pressurization at 300 MPa→chilled storage.
8. Development of long-term preservative technique of abalone
○ In this study, dried or frozen abalone were developed. For dried abalone, freeze-drying (FD) and boiled hot-air drying (BHD) methods were compared. FD treatment showed best recovery after rehydration with maintaining original color. The only disadvantage of FD treatment was that the abalone was easy to absorb moisture during storage comparing to those treated BHD. Vacuum-packaging was necessary to store FD treatment.
○ For frozen abalone, pressurization followed by freezing extended shelf-life of abalone for more than 32 weeks. High pressure processing could be effective pretreatment for frozen abalone production.
○ To develop quick freezing technique, pressure-shift freezing (PSF) was conducted under varying pressure levels and compared with high pressure subzero-temperature processing. The results indicated that PSF at 100 MPa was the best freezing condition for abalone.
○ Established processing of frozen abalone was washing→vacuum-packaging→pressurization→quick freezing (IQF).
9. Development of optimal packaging system for abalone distribution
○ In the present study, various packaging methods (modified atmosphere, vacuum and skin vacuum packaging) were compared.
○ MA packaging was effective to extend shelf-life of abalone, however, the MA packaging was impossible to apply abalone pasteurized by high pressure processing.
○ Skin vacuum packaging showed a potential application to improve value of test products, whereas the usage of skin vacuum was not favorable to abalone containng shell or dried product.
○ Meanwhile, abalone muscle product was successfully packaged by skin vacuum and the packaging was stable under freezing condition.
