• Korean Journal of Microbiology
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• v.33 no.2
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• pp.131-135
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• 1997

Several microorganisms capable of producing protopectinase, which catalyzes dissociation of plant tissue to single cells, were isolated from soils. Crude enzymes prepared from culture supernatants of the strains released potato cells as a single cell from potato tissues. One of the isolated strains showing higher activity of protopectinase was selected and identified as Rhizopus sp. from the morphological characteristics. For preparing single cells from potato tissues, optimum enzyme activity of protopectinase, which was prepared from culture filtrate of Rhizopus sp. R2, was obescrved at $40^{\circ}C$ and pH 4.

• Culinary science and hospitality research
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• v.18 no.2
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• pp.162-171
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• 2012

This study was conducted to investigate the changes of macerating properties from grape suspensions for which both were treated with protopectinase(PPase) and mechanical maceration stored at $4^{\circ}C$ for 28 days. Changes of macerating properties such as pH, total acidity, color, total polyphenol and antioxidant activity of suspensions after enzymatic hydrolysis were determined before and after heating, and microscopic observation made on suspensions containing single cells. With the PPase, grapes were enzymatically macerated to separate cells to primary cell wall without damage. Also, the changes of macerating properties in grape suspension treated with PPase and after heat treatment at $80^{\circ}C$ for 30 min were more stable than those of mechanical maceration, indicating the thermal stability. Thus, the PPase treatment for grapes could be a better choice for preparing highly valuable and functional processed food as well as for prolonging preservation periods.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.64-68
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• 2004

Cell-separating enzyme (Sumyzyme MC) was used to investigate enzymatic maceration of strawberry, sweet persimmon, kiwi, onion, garlic, and cucumber, Maceration rate, volume, brix, color, particle size distribution, and viscosity were determined, and microscopic observation made on suspensions containing single cells. Sweet persimmon and strawberry showed over 90% meceration rates, and kiwi showed 80%. Color, storage test, and sensory evaluations of single-cell suspensions and their filtrates were performed before and after sterilization. Total dietary fiber contents of raw material and single-cell suspension of garlic were 30.77 and 18.55%, respectively, Results indicate fruit and vegetable suspensions produced through enzymatic disintegration using cell-separating enzyme can be utilized as basic materials in the manufacture of single-cell foods.

• The Korean Journal of Applied Statistics
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• v.33 no.4
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• pp.511-526
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• 2020

Single-cell RNA-sequencing (scRNA-seq) data consists of each cell's RNA expression extracted from large populations of cells. One main purpose of using scRNA-seq data is to identify inter-cellular heterogeneity. However, scRNA-seq data pose statistical challenges when applying traditional clustering methods because they have many missing values and high level of noise due to technical and sampling issues. In this paper, motivated by analyzing scRNA-seq data, we propose a novel spectral-based clustering method by imposing different weights on genes when computing a similarity between cells. Assigning weights on genes and clustering cells are performed simultaneously in the proposed clustering framework. We solve the proposed non-convex optimization using an iterative algorithm. Both real data application and simulation study suggest that the proposed clustering method better identifies underlying clusters compared with existing clustering methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.29-34
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• 2003

In development of the processed food, it is important not only to make the food delicious but to enhance its storage span and thermal stability without change in color, which greatly affects the tastes. Protopectinase (PPase) from Bacillus subtilis EK11 hydrolyses or dissolves protopectin in the middle lamella of plant tissues with the resultant separation of plant cells from each other, called enzymatic maceration. With the PPase, persimmon was enzymatically macerated to separate cells to primary cell wall without damage. Recovery rates of persimmon treated with PPase and mechanical maceration were 95% and 85%, respectively. Total and reducing sugars, crude protein and fat in the enzymatic maceration were well preserved as in the mechanical maceration. Importantly, over 50% of vitamin C, which is the most unstable component during the mechanical maceration, remained with an intact form for one day after the enzymatic treatment. When the suspensions of persimmon macerated with both treatments were stored at 4$^{\circ}C$ for 9 days, the mechanically macerated persimmon suspension was decolorized, whereas decolorization, was not found in the enzymatically macerated persimmon suspension. Moreover the mechanically macerated persimmon was greatly deteriorated after heat treatment at 10$0^{\circ}C$ for 60 min, whereas cells of the enzymatically separated persimmon suspension appeared to be stable, indicating increased thermal stability Thus, the PPase treatment of persimmon could be a better choice for preparation of highly valuable and functional processed food as well as for increase in preservation period.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.58-63
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• 2004

Cell-separating enzymes were used to investigate enzymatic maceration of watermelon and muskmelon containing single cells. Watermelon and muskmelon were macerated with Macerozyme A and Sumyzyme MC for 30-120min. Changes in maceration properties such as yields, color, viscosity, total sugar, total pectin, total polyphenol, particle size distribution, minerals, and free amino acids of suspensions after enzymatic disintegration were investigated. Contents of biochemical components in the supernatant of suspensions increased with increasing treatment time. Suspensions containing single cells showed good thermal stability without affecting original qualities. Mineral content of single-cell suspension was higher than those of watermelon and muskmelon juices. Potassium contents of single-cell suspension and juice were 240.8 and 172.7 mg%, respectively. Results suggest single-cell suspensions of watermelon and muskmelon can he utilized as ingredients for new beverages.

• Food Engineering Progress
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• v.13 no.4
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• pp.348-351
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• 2009

In this study, the effects of gums (guar gum, xanthan gum, locust beam gum) on the activity of polygalacturonase(PGase) were examined. PGase activity was assayed by measuring the release of reducing groups from polygalacturonic acid. Guar gum, xanthan gum and locust bean gum were capable of increasing the catalytic activity of the PGase by 105%, 87% and 90%, respectively. Carrot was macerated by Macerozyme R-200 with gums and the yield of the maceration reaction for the production of carrot single cells was increased up to 13% in the presence of guar gum. This suggested that gums stated above can be used as good enhancers not only for the catalytic activity of the PGase but also for the production of carrot single cell.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.3
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• pp.401-406
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• 2000

In development of the processed food, it is important not only to make the food delicious but to enhance its storage span and thermal stability without change of the food quality in color, which greatly affects the tastes of customers. Protopectinase (PPase) from Bacillus subtilis EK11 hydrolyses or dissolves protopectin in the middle lamella of plant tissues with the resultant separation of plant cells from each other, called enzymatic maceration. With the PPase, Kiwifruit was enzymatically macerated to separate cells to primary cell wall without damage. Yields of kiwifruit treated with PPase and mechanical maceration were 82% and 60%, respectively. Total and reducing sugars, crude protein and fat in the enzymatic maceration were well preserved as in the mechanical maceration. Importantly, over 95% of vitamin C, which is the most unstable component in application of the mechanical maceration, remained with intact form for one day after the enzymatic treatment. When the suspensions of kiwifruit macerated with both treatments had been stored at $4^{\circ}C for 6 days, the suspension of kiwifruit mechanically macerated was decolorized. whereas decolorization was not found in the enzymatically macerated kiwifruit. Moreover, the mechanically macerated kiwifruit was greatly deteriorated after heat treatment at $100^{\circ}C for 60 min ; the cell suspension of the exzymatically separated kiwifruit appeared to be stable, indicating the thermal stability. Thus, the PPase treatment could be a better choice for preparation of the highly valuable and functional processed food of kiwifruit as well as for prolonging the preservation period of the processed kiwifruit.

• Food Science and Preservation
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• v.13 no.3
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• pp.351-356
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• 2006

This study was carried out to investigate the change of functional component and volatile flavor components from garlic for which both were treated with protopectinase (PPase) and mechanical maceration during storage period. Alliin content of gallic suspensions macerated mechanically were 11.0 mg/g at 0 day and 6.6 mg/g at 24 day. Whereas alliin content of garlic treated with PPase were 8.5 m/g at 0 day and 7.0 mg/g at 24 day. Importantly, over 40% of alliin which is the most unstable component during the mechanical maceration remained with an intact form for 24 day after the enzymatic treatment. The flavor component from gallic suspensions were extracted by solid-phase microextraction (SPME) and were analyzed and identified by gas chromatography (GC) and chromatography/mass spectrometry (GC/MS). The number and concentrations of flavor components of gallic macerated mechanically were increased during storage period, and total 18 kinds of flavor compounds were identified. Thus, the PPase treatment of garlic could be a better choice for preparation of the highly valuable and functional processed food as well as for prolonging the preservation period.

• Microbiology and Biotechnology Letters
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• v.29 no.3
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• pp.176-180
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• 2001

In plant tissues intercellular cementing portion called as middle lamella consists of high proportion of protopectin that is water insoluble form of pectin on their backbone Protopectinase (PPase) a heterogeneous group of enzymes that hydrolyze or dissolve the insoluble protopectin in plant tissues by restricted depolymerization liberates water solu- ble pectin with the resultant separation of plant tissues that have been protected against environmental shock by rigid cel wall . Bacillus subtilis EKll was most effective for PPase Production For increasing of PPase productivity effects of glucose concentrations, pHs and aeration rates were studied in batch culture The most proper concentra- tion of glucose pH and air condition for PPase Production were 1% 8.0 and lvvm respectively In these condi- tion PPase productivity was $84,364 UL^{-1}$ $h^{-1}$ and increased about 15.6 times than flask fermentation.