• Food Science and Biotechnology
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• v.16 no.2
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• pp.294-298
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• 2007

The actinidin (EC 3.4.22. 14) found in kiwifruit is a cysteine protease. In order to obtain the actinidin gene from the Chinese wild kiwifruit, primers were designed on the basis of the actinidin gene of Actinidia deliciosa, the New Zealand kiwifruit. The 1.2 kb DNA fragment was acquired from the total RNAs of Chinese wild kiwifruit via reverse transcription polymerase chain reaction (RT-PCR), and its DNA sequence was analyzed. Its sequence was determined to share 98.4% homology with the actinidin gene of A. deliciosa. In order to verity the actinidin gene isolated from the Chinese wild kiwifruit in Escherichia coli, the mature gene was amplified via PCR and expressed in E. coli under the control of the T7lac promoter. The actinidin was expressed in E. coli as inclusion bodies, which were solubilized with urea and refolded. The protease activity of the refolded protein was approximately twice as high as that of E. coli BL2l (DE3).

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.554-558
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• 2010

In the study, the protease activity of kiwifruit (Actinidia deliciosa Planch) cultivated in Korea was estimated, with specific examination of proteolytic effects on myofibrilar protein. The crude protease extract of kiwifruit was prepared in two ways; one in which the kiwifruit was homogenized with buffer followed by centrifugation, and the other were the supernatant was precipitated by saturated ammonium sulfate followed by dialysis. The former had 21.23 mM/mL of protease activity, which corresponded to 112.28 mM/g kiwifruit utilized, and the latter had 11.58 mM/mL and 45.80 mM/g of kiwifruit. The crude protease extract of the kiwifruit showed high specificity for casein substrate followed by bovine serum albumin, egg white, collagen, and elastin, in order. The enzyme lost proteolytic activity in acidic conditions such as pH 2-3, and at high temperatures over $60^{\circ}C$. It showed optimal activity in both pH 3.0 and pH 7.5 as well as at $40^{\circ}C$ for casein substrate and at $50^{\circ}C$ for myofibrilar protein substrate. The proteolytic activity toward casein was high with up to 0.5M salt, followed by a sharp decrease beyond this concentration. On the other hand the proteolytic activity for myofibrilar protein decreased steadily with increasing of salt concentration. Kiwifruit has been used as a for meat tenderizer for in home cooking and these results support the its tenderizing effectiveness of kiwifruit especially for Korean style marinating of meat for cooking.

• Fashion & Textile Research Journal
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• v.11 no.3
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• pp.496-501
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• 2009

In this study, a kiwifruit-produced protease was used to improve the quality of the wool and silk fabrics. The wool and silk were treated with the actinidin from kiwifruit. Following this protease treatment, changes in the surface of a single yarn of the fabrics were observed via both an optical microscope and a scanning electron microscope (SEM). In order to determine the amount of dye uptake in the fabric, changes in the K/S value of the wool and silk were measured by spectrophotometric analysis. Also, we performed a tensile strength examination to determine variation in their mechanical properties. By increasing the protease treatment time to 48h, the dyeing properties of fabrics were enhanced, and the surfaces of the single yarns of the fabrics became smoother, because of the removal of soil and scale in them. However, no mechanical changes were detected in the fabrics. Thereby, we suggest that the kiwifruit-produced actinidin treatment can improve the quality of the fabrics.

• Food Science of Animal Resources
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• v.23 no.3
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• pp.193-199
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• 2003

In order to investigate the meat tenderizing effects of pear, pineapple and kiwifruit, crude protease was prepared from each fruit and treated with actomyosin in a single manner or mixed type in several combination. Actomyosin was incubated with various proteases for 24 hrs under three different pH condition, and its degrading performance was evaluated by the SDS-PAGE. Pear extract showed an active degrading activity for actomyosin at pH 5.3 and 7.0. But, little actomyosin degradation was observed at pH 8.0. Actomyosin was strongly degraded by the treatment of protease from pineapple at all different pHs(5.3, 7.0 and 8.0). Kiwifruit protease extract has shown actomyosin degradation activity 1hr after treatment at pH 5.3 and pH 7.0. Meanwhile, the mixture of pear and pineapple extracts(l:l, w/w) showed much more degradation than the results of singular manner treatment at pH 5.3 and 7.0. When the pear protease was mixed with kiwifruit protease(l:l, w/w), the performance of actomyosin degradation was similar to the results of each single protease treatment. When the mixture was made of pineapple and kiwifruit extracts, actomyosin degradation was almost the same as the result of treatment of pineapple protease only. When those three proteases were mixed together(l:l:l, w/w/w), actomyosin degrading activities was in time dependent manner at pH 5.3. In summary, pear protease can be used potentially as a meat tenderizer when it was mixed with pineapple or kiwifruit rendering proper tenderization of the meat.

• Animal Bioscience
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• v.37 no.5
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• pp.908-917
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• 2024

Objective: Although pork loins is not a tough meat, they need to develop meat products with a soft texture for the elderly. This study focused on the physicochemical properties and tenderness characteristics of pork loin injected with green kiwifruit juice (GRJ) and gold kiwifruit juice (GOJ) during various incubation times. In addition, the antioxidant activities of hydrolysate derived from the hydrolysis of pork loin by kiwifruit juice protease were evaluated. Methods: The pork loin was injected with 10% and 20% GRJ and GOJ, under various incubation times (0, 4, 8, and 24 h). Then, the physicochemical properties and tenderness of pork loins were measured. 2,2- diphenyl-1-picrylhydrazyl radical scavenging activity and reducing power were conducted to determine hydrolysate's antioxidant activities derived from pork loin's hydrolysis by kiwifruit juice protease. Results: GRJ had greater tenderizing ability than GOJ, even at the 10% addition. When kiwifruit juice was injected into pork loin, the tenderness increased with increasing incubation time. This was confirmed by the decrease in intensity of the myosin heavy chain (MHC) band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In particular, the MHC band decreased at 8 h for both 10% GRJ and 20% GOJ and at 4 h for 20% GRJ alone. The highest myofibril fragmentation index and peptide solubility were observed in pork loin treated with 20% GRJ compared to the other treatments during incubation. The 10% GRJ and 20% GOJ treatments showed similar levels of antioxidant activity of the protein hydrolysates in pork loin, and 20% GRJ showed the highest activity among the treatments. Conclusion: Kiwifruit juice had protease activity, and GRJ was more useful for tenderizing meat products than GOJ. Thus, GRJ at 10% could be a potential agent to tenderize and enrich the natural antioxidant activity through the proteolysis of pork loin.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.569-574
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• 1989

These studies were conducted to investigate the purification and characterization of Kiwifruit protease, and the results obtained were as follows The protease was purified by ammonium sulfate fractionation, Sephadex G-100 filtration and DEAE-Sephadex A-50 column chromatography and purified enzyme gave a single protein band on polyacrylamide gel electrophoresis The specific activity of purified enzyme was 30,10 units/mg protein and the yield was 7.48. The purified enzyme showed a high affinity for casein and hemoglobin. The optimal pH and temperature for enzyme activity were 7.0 and $45^{\circ}C$, respectively. The enzyme activity was strongly inhibited by $HgCl_2,\;MnSO_4$. However. the enzyme was activated by cysteine and EDTA. The Michaelis constant for casein was calculated to be 50.5mg/ml according to the Line weaver-Burk method, and its molecular weight was determied as 23,500 by polyacrylamide gel electrophoresis.

• Korean journal of food and cookery science
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• v.26 no.3
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• pp.323-329
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• 2010

Studies on the tenderizing effect of fruits has been limited even though fig, kiwifruit, pear, and pineapple cultivated in Korea are utilized commonly during cooking for their proteolytic properties. Therefore, the characteristics of these fruits were investigated by treating beef with their crude protease extracts. The protease effects of crude protease extract from the fruits on casein and myofibrilar protein were in the following order : pineapple > kiwifruit > fig > pear. Electrophoretic analysis results found that pineapple, kiwifruit, and fig cleaved myosin heavy chain into smaller fragments. The myofibrilar fragmentation ratio of crude protease extracts was the highest for pineapple whileas the lowest for pear. Ground fruits (5% and 10%) increased amounts of soluble nitrogen and decreased shear force of beef. Pineapple was the most effective while pear was the least effective. Decrease in springiness and gumminess was observed by texture profile analysis of beef treated with fruits, especially pineapple and kiwifruit. Among the 5% treatments, pineapple and kiwifruit produced the highest tenderness. Additionally, 10% treatment was less preferable than the 5% treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1461-1466
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• 2013

In this study, we ascertained the characteristics of crude protease extracted from fruits (fig, kiwifruit and pineapple) as well as traditional Korean fermentation starters (bio nuruk, traditional nuruk, meju and rice koji) to determine their suitability for industrial application. Crude protease extracted from traditional Korean fermentation starters was found to have a higher optimum temperature ($70^{\circ}C$) and salt concentration (1~3%) but a lower optimum pH (3~6) value compared to the corresponding values for the protease extracted from fruits. On comparison, the total activities of protease per gram unit follow the order: bio nuruk> rice koji> traditional nuruk> fig> pineapple> meju> kiwifruit. Based on our results, we conclude that protease extracted from traditional Korean fermentation starters has potential for application in food industry, for example, as a meat tenderizer for sausage manufacturing and as a protease for cheese production.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.641-645
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• 2001

To utilize the by-products from whelk processing, whelk internal organ jeotgal was manufactured by adding pineapple and kiwifruit juices containing bromelain and actinidin, respectively. The protease activities of pineapple and kiwifruit juices were 52 and 248 unit/mL, respectively. 1 kg ground whelk internal organ was immersed to 12.5% salt concentration and then the 20, 50, or 100 mL of fruit juice were added in it. the quality of products fermented for up to 70 day at 1$0^{\circ}C$ was observed. Jeotgal wit pineapple juice showed lower pH and higher amino nitrogen content than with kiwifruit juice on 70 day of fermentation. the total nitrogen contents was the highest on 30 day of fermentation and stable thereafter. Although total numbers of microorganism were increased as fermentation progressed, there were no correlations among the juices or its adding amounts. It was thought that interactions between kinds of natural microflora and the proteases from fruit juices, and other constituents in jeotgal affected total nitrogen content of jeotgal and the growth rate of natural microorganisms. Of the all jeotgals in this study, no coliform was found It is suggested that the preparation of jeotgal with pineapple or kiwifruit juice is effective aspect of safety and quality.

• Journal of Life Science
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• v.12 no.6
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• pp.752-758
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• 2002

This study was investigated on properties and thermostability of gelatin-degrading proteinases in the fruit of Actinidia chinensis (kiwifruit) for the industrial application. Three gelatin-degrading proteinases (PI, PII and PIII) were detected from the pulp of fruits. The molecular weights of these proteinases, PI, PII and PIII, were approximately 220 kD, 51 kD, and 26 kD respectively, on the basis of gelatin-containing SDS-PACE. The optimum pH of these proteinases ranged from 2.0 to 5.0 with a maximal activity at pH 4.0. These proteinases had a high sensitivity to E-64 and iodoacetate which are cysteine protease inhibitors, and required DTT, cysteine, and $\beta$-mercaptoethanol for their activities which are stimulators for cysteine proteases. These results indicate that these proteinases are cysteine proteinases and the proteinase PIII is actinidin (EC 3.4.22.14), based on the molecular weight and/or susceptibility against proteinase inhibitors. These proteinases were strongly activated by $Ca^{2+}$, $Mg^{2+}$ and $Mn^{2+}$, whereas strongly inhibited by Zn$^{2＋}$ and Hg$^{2＋}$. However, these proteinases have slightly different susceptibility against other cations ($Ca^{2+}$, $Cu^{2+}$, $Al^{3+}$, $Ca^{3+}$. The temperature stability of proteinase PIII was more stable than proteinases PI and PII. Moreover, proteinase PIII remained stable below $50^{\circ}C$ for 48hr, showing the residual activity above 75% of the enzyme activity.