• Korean Journal of Food Science and Technology
• /
• v.22 no.3
• /
• pp.234-240
• /
• 1990

Attempts have been made to optimize the hydrolysis conditions of the oyster and the mussel by the commercial proteolytic enzymes. Raw materials were digested with seven different commercial enzymes, and their quality parameters measured in terms of degree of hydrolysis and content of free amino nitrogen, nucleic acid-related substances. and free amino acids as well as sensory evaluation of optimization of their hydrolysis conditions. As a result, following enzymes have been disclosed as effective for enzymatic digestion: MKC-HT proteolytic, alcalase 0.6L and thermease for the oyster whereas MKC-acid fungal protease and thermoase for the mussel, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.14 no.2
• /
• pp.66-71
• /
• 1981

In order to study the decomposition process of glycogen and protein of oyster during fermentation with salt, and the relationship between their breakdown products, the amounts of free reducing sugars and lactic acid were determined, and amino acid compositions were analysed. In addition, the amount of the available lysine which may help us to estimate the reaction of the free reducing sugars with the free amino acids was also determined. Glycogen and protein were gradually decomposed to free reducing sugars and lactic acid, and free amino acids, respectively, and the available lysine was slightly decreased during the fermentation process. Glutamic acid, aspartic acid, lysine and proline were relatively rich in the amino acid com-position of raw oyster protein while amino acids such as tryptophan, methionine, histidine and tyrosine were poor. It was noted that the decreased amino acids in the protein from the fermented oyster were valine, histine, isoleucine and lysine. As a respect to the free amino acids, proline, taurine, glycine, glutamic acid and alanine were abundant in the raw oyster and reached up to $69\%$ of the total fret amino acids. In the fermented oyster, proline, glutamic acid, glycine, alanine, aspartic acid and lysine were prevalently contained and marke about $65\%$ of the total free amino acids. The contents of free amino acids such as lysine, arginine, aspartic acid, glutamic acid, cysteine, isoleucine and tyrosine increased during fermentation while those of taurine, proline and leucine decreased.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.2
• /
• pp.244-248
• /
• 2015

We explored the efficiency of natural antibacterial agents used to enhance the self-life and sensory properties of shucked and packed Pacific oyster Crassostrea gigas, which are in high demanded. First, we screened natural resources exhibiting antibacterial activity against food spoilage and pathogenic bacteria. Of theses, ignited oyster shell powder (IOS) and the natural food preservative, lactic acid bacteria fermented powder (LBF), were selected for further study considering the efficacy, mass production, and cost. The addition of 0.1% IOS (W/V) and 0.5% LBF (W/V) to shucked and packed oyster optimally extended the shelf-life without affecting the sensory evaluation. The results obtained in this study will provide a clue to enhance self-life in raw oyster products.

• Korean Journal of Food Science and Technology
• /
• v.20 no.3
• /
• pp.385-391
• /
• 1988

In an attempt to develop natural seasoning materials by use of shellfishes and crustaceans, contents of taste components such as amino acids, nucleotide and its derivatives, the extractability of oyster (Crassostrea gigas), sea mussel(Mytilus coruscus) and crab(Portanus tribuerculata) were investigated. As a result of chemical analysis and sensory evaluation, the optimum condition of extraction could be concluded as extracting fresh or frozen raw materials for about 40 min. at $95^{\circ}C$ with 1.5 to 2 times of water by volume. The contents of free amino acids in the extractions were much in sequence as crab(1,886 mg%), mussel(765 mg%) and oyster(554 mg%), and the dominant amino acids in each extracts were identified as glutamic acid, alanine, glycine, proline and arginine in oyster, threonine, alanine, arginine, glycine and glutamic acid in mussel, arginine, proline, lysine, alanine and threonine in crab respectively. In addition, the major nucleotides affecting as taste enhancer of each extracts were estimated as inosine in oyster and crab, and inosine monophosphate in mussel respectively.

• Food Science and Preservation
• /
• v.9 no.1
• /
• pp.51-55
• /
• 2002

Changes in food components of oyster mushroom Kimchi were investigated during storage at 20$^{\circ}C$. The pH of raw oyster mushroom Kimchi (ROMK) was higher than that of Chinese cabbage Kimchi (control) at initial stage, but it was lower than that of control after 1 day of storage. pH of blanched oyster mushroom Kimchi (BOMK) was slightly higher than that of controls The titratable acidity of oyster mushroom Kimchi was in inverse state to the pH. Amino acid nitrogen content of Kimchi tended to increase during storage, the content of ROMK was higher than that of control, the content of BOMK was not different from that of control. The reducing sugar content of Kimchi decreased significantly during storage, the content of ROMK was higher than that of controls the content of BOMK was slightly lower. The bacterial number of control increased rapidly at 2 days fermantation and reached plateau afterward. The number of ROMK tended to he alike that of control during storages the number of BOMK was fewer than that of control. On the taste panel of Kimchi after 1 day of storages ROMK obtained higher score than BOMK but the score was lower than control.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.49 no.6
• /
• pp.772-778
• /
• 2016

To develop a value-added product from individually quick-frozen oysters Crassostrea gigas (IQFO), we prepared a retort pouched oyster soup (RPOS) from IQFOs and characterized its processing conditions and quality metrics. We found that the most appropriate manufacturing process for the RPOS consisted of half-thawing and washing raw IQF oysters, blanching, adding them to the retort pouch along with other ingredients (base soup stock, IQF oyster extract, radish, bean sprouts, garlic, and red pepper), sealing, retort sterilization ($120^{\circ}$, F0-value 10 min.), cooling, and packaging inspection. The moisture, crude protein, pH and salinity of the RPOS were 91.0%, 2.8%, 6.20 and 0.9%, respectively. The total amino acid content of the RPOS was 2,163.8 mg/100 g, and the main amino acids were glutamic acid, aspartic acid, leucine, proline, lysine and arginine. The primary inorganic ions were Na, K, S and Zn. In taste compounds, total free amino acid content was 313.4 mg/100 g, and the main free amino acids were glutamic acid, taurine, proline, hydroxyproline, aspartic acid, glycine, alanine, valine, lysine and arginine. This RPOS has good storage stability and organoleptic qualities compared with commercial retort pouched shellfish soup, and is suitable for commercialization as a value-added instant seafood soup.

• Journal of Environmental Science International
• /
• v.28 no.10
• /
• pp.851-861
• /
• 2019

In this study, we performed a sediment elution experiment to evaluate water quality in terms of phosphorus, as influenced by the dissolved oxygen consumed by sediments. Three separate model column treatments, namely, raw, calcined, and sonicated oyster shell powders, were used in this experiment. Essential phosphorus fractions were examined to verify their roles in nutrient release from sediment based on correlation analyses. When treated with calcined or sonicated oyster shell powder, the sediment-water interface became "less anaerobic," thereby producing conditions conducive to partial oxidation and activities of aerobic bacteria. Sediment Oxygen Demand (SOD) was found to be closely correlated with the growth of algae, which confirmed an intermittent input of organic biomass at the sediment surface. SOD was positively correlated with exchangeable and loosely adsorbed phosphorus and organic phosphorus, owing to the accumulation of unbound algal biomass-derived phosphates in sediment, whereas it was negatively correlated with ferric iron-bound phosphorus or calcium fluorapatite-bound phosphorus, which were present in the form of "insoluble" complexes, thereby facilitating the free migration of sulfate-reducing bacteria or limiting the release from complexes, depending on applied local conditions. PCR-denaturing gradient gel electrophoresis revealed that iron-reducing bacteria were the dominant species in control and non-calcined oyster shell columns, whereas certain sulfur-oxidizing bacteria were identified in the column treated with calcined oyster powder.

• Journal of Food Hygiene and Safety
• /
• v.33 no.4
• /
• pp.248-254
• /
• 2018

To assess the risk of V. parahaemolyticus infection caused by consumption of raw oysters in Korea, contamination levels during the retail-to-table route of oysters was modeled to predict V. parahaemolyticus growth based on temperature and time. The consumed amount data of the KNHANES and the standard recipe of RDA were applied. A consumption scenario for exposure assessment was developed and combined with a Beta-Poisson dose-response model. The estimated probability of illness from consumption of pathogenic V. parahaemolyticus in raw oysters during three separate months (April, October, and November) was $5.71{\times}10^{-5}$ (within the 5th and 95th percentile ranges of $2.71{\times}10^{-8}$ to $1.03{\times}10^{-4}$). The results of the quantitative microbial-risk assessment indicated that the major factors affecting the probability of illness were the initial contamination level at the retailer, the consumed amount, the prevalence of pathogenic strains [tdh or trh genes], and exposure temperature and time.

• Applied Biological Chemistry
• /
• v.28 no.1
• /
• pp.1-7
• /
• 1985

Exo-maltotetraohydrolase produced by Pseudomonas stutzeri IAM 12097 was characterized with respect to substrate specificity, the reaction products and hydolysis rate on various carbohydrates. Maltopentaose, maltoheptaose, soluble starch, amylose, amylopectin, oyster glycogen and gelatinized starch of corn, potato, glutinous rice, green banana and arrow root were hydolyzed by this enzyme, but ${\alpha},{\beta},{\gamma}-cyclodextin$, sucrose, raffinose, lactose, pullulan, maltose, maltotriose and maltotetraose were not hydrolyzed. Among oligosaccharides, maltohexaose was favorably hydrolyzed by this enzyme and the main reaction product of oligosaccharides and polysaccharides was maltotetraose. Addition of pullulanase to this enzyme increased the hydolysis rate on gelatinized starches. tut it did not on raw starches. Among various starches, corn starch was favorably hydrolyzed by this enzyme, whereas it acted on potato starch, arrow root starch and high amylose corn starch weakly.

• Journal of Food Hygiene and Safety
• /
• v.27 no.4
• /
• pp.388-394
• /
• 2012

The present study was carried out to assess the dietary exposure and the risk for arsenic (As) and mercury (Hg) through mushrooms intake. Various samples (n = 536) covering 17 kinds of mushrooms were collected from retail outlets and markets in Korea. The contents of As were 0.003 (King oyster) ~ 1.952 (Matsutake) mg/kg in raw mushrooms and 0.015 (Fuscoporia obliqua) ~ 16.95 (Matsutake) mg/kg in dry mushrooms, respectively. The contents of Hg were 0.001 (King oyster) ~ 0.030 (Matsutake) mg/kg in raw mushrooms and 0.004 (Oyster) ~ 0.588 (Matsutake) mg/kg in dry mushrooms, respectively. The mean dietary exposures of As was $0.151{\mu}g$/day, taking 0.005% of provisional tolerable weekly intake (PTWI). The mean dietary exposures of Hg was $0.022{\mu}g$/day, corresponding to 0.071% of PTWI. Therefore, the level of overall dietary exposure to As and Hg for Korean population through mushroom was far below the levels recommended by Joint FAO/WHO Expert Committee on Food Additivies, indicating little possibility of concern.