• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.6
• /
• pp.350-355
• /
• 2007

The optimal substrates and reaction flavoring conditions were examined to develop pearl oyster extract (POE) flavor using the Maillard reaction under a model system. The sugar for the Maillard reaction was glucose, and the amino acid was cysteine, with glycine as the reaction substrate. A three-dimensional response surface method was used to monitor the dynamic changes of the substrates during the Maillard reaction. To enhance the flavor of POE, a two-step enzymatic hydrolysate (Brix $20^{\circ}$) was reacted with the precursors (1:1, v/v). A 2:1:1 mixture of 0.4 M glucose:0.4 M glycine:0.4 M cysteine (v/v) was selected as a suitable reaction system for the reappearance of baked potato odor and boiled meat odor, and masking the shellfish odor. The two-step enzymatic hydrolysate and selected precursors were reacted in a high-pressure reactor to optimize the reaction parameters. The optimum conditions were 150 minutes at $120\;^{\circ}C$ and pH 7.0. The pH was the most critical factor for the response of the baked potato odor and masking the shellfish odor, while the reaction time affected the reappearance of the boiled meat odor.

• Korean Journal of Food Science and Technology
• /
• v.29 no.5
• /
• pp.839-846
• /
• 1997

Addition of three natural flavoring materials, hydrolyzed vegetable protein (HVP), hydrolyzed animal protein (HAP) and yeast extract (YE), into 0.2 M cystine-0.1 M lactose-0.1 M maltose solution (control) was studied for development of meat-like flavor by Maillard reaction. The HVP, HAP and YE were added individually at various concentrations and were mixed at selected concentration in order to compare their effects. The absorbance, color, sensory characteristics and volatile compounds of the solutions after the reaction at $100^{\circ}C$ for 8 hr were measured. The results showed that the absorbances of reaction solution at 420 nm and 278 nm were increased as reaction time and the concentration of the natural flavoring material increased. Also ‘L’ values of reaction solutions added with HVP, HAP or YE decreased while the ‘b’ value increased slightly. From the results of sensory evaluation 1.16% HVP, 0.94% HAP, 1.48% YE or 1.16% HVP + 0.94% HAP were selected as the appropriate substrates for the meat-like flavor development. The volatile compounds identified by GC/MS for the control and those added with 1.16% HVP or 1.16% HVP+0.94% HAP were 1 hydrocarbons, 9 aldehydes, 5 ketones, 1 ester, 5 alcohols, 2 aromatics(benzene), 2 furans, 1 sulfur compound.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.1
• /
• pp.102-109
• /
• 2014

Crab-like flavoring base (CFB) was made from a concentrated snow crab cooker effluent (SCCE) containing five food additives (proline, glycine, arginine, methionine, fructose) using reaction flavor technology (RFT). The volatile flavor compounds in CFB were compared between raw (SCCE) and control (without food additives) samples using solid phase microextraction (SPME) and gas chromatography with mass selective detector. A total of 74 compounds were detected in all samples (30 raw samples, 34 control samples, 55 CFB samples). A total of 22 nitrogen-containing compounds, including 19 pyrazines and 3 pyridines, were formed through RFT and increased 27 times compared to the control. Dimethyl trisulfide and dimethyl disulfide were predominant sulfur-containing compounds that increased through RFT, while aromatic compounds decreased through RFT. Seven compounds, tetramethylpyrazine, 2-ethyl-3,5,6-trimethylpyrazine, 2,3,5-trimethyl-6-(3-methylbutyl)pyrazine, 2-ethyl-3,5-dimethylpyrazine, 2,5-dimethyl-3-(3-methylbutyl)pyrazine, 2-ethyl-3,6-dimethylpyrazine, and 2-decanone potentially have a role in CFB odor by Pearson's correlation analysis.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.47 no.6
• /
• pp.733-739
• /
• 2014

To develop an effective use for poor-quality individually quick-frozen (IQF) oysters Crassostrea gigas stored for a long period, the extract conditions, quality characteristics, and optimum reaction flavoring (RF) conditions of a complex extract from these IQF oysters were investigated. The moisture, pH, and volatile basic nitrogen contents of IQF oysters stored for 18 months (18M-IQFO) were 77.9%, 6.32, and 17.9 mg/100 g, respectively. Three different kinds of extract were prepared from 18M-IQFO: a hot-water extract (HE), scrap enzymatic hydrolysate (EH), and complex extract (CE). The respective extracts contained 5.5, 8.6, and 6.6% crude protein and 281.7, 366.0, and 343.0 mg/100 g amino nitrogen, and had 811, 359, and 1,170 mL/kg extraction yields. The CE was superior to the traditional HE in terms of the extraction yield, amino-nitrogen content, and organoleptic qualities, except for the odor. To improve flavor via the Maillard reaction, the reaction system used to produce a desirable flavor comprised CE (Brix $30^{\circ}$), 0.4 M glucose, 0.4 M glycine, and 0.4 M cysteine solution (4:2:1:1, v/v). The reaction time and pH were the independent variables, and the sensory scores for baked potato odor, masking shellfish odor, and boiled meat odor were the dependent variables. The surface response methodology (RSM) analysis of the multiple responses optimization gave a reaction time of 120.6 minutes and pH 7.33 at $120^{\circ}C$. The reaction improved the flavor of CE considerably, as compared to that of the unreacted extract.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.2
• /
• pp.104-113
• /
• 2012

Crab-like flavorants (CFs) were made from snow crab cooker effluent (SCCE) using response surface methodology (RSM) and reaction flavoring technology (RFT). Type A CF was made from SCCE via RSM, RFT, adding starch syrup, centrifugation, and microfiltration. Type B was made from type A by adding the food additives dimethyl sulfide, ethyl valerate and fish sauce. The stability of the CFs was evaluated in terms of the color values, sensory evaluation, and flavor profiles after storage for 90 days at three different temperatures: 10, 20, and $30^{\circ}C$. The compounds, ethanol and 3-methyl-1-butanol, were considered key components of off-flavor and a decrease in dimethyl-2-vinylpyrazine affected the occurrence of off-flavor. It may be a microbial metabolite arising from contamination and lab-scale micro-filtration. At the lowest temperature ($10^{\circ}C$), the decrease in volatile compounds, such as pyrazines, was not as dramatic as at $20^{\circ}C$ and $30^{\circ}C$ and alcohol formation was prevented or delayed. Therefore, it is necessary to store CFs at < $10^{\circ}C$ with suitable sterilization to preserve volatile flavor compounds and prevent off-flavor from occurring.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.1
• /
• pp.128-134
• /
• 2014

To develop a crab-like flavorant from snow crab cooker effluent (SCCE, $20^{\circ}Brix$), optimal reaction conditions were determined using response surface methodology (RSM) combined with reaction flavoring technology (RFT). Using five variables (proline, glycine, arginine, methionine, fructose), RSM based on a five-level central composite design was applied to evaluate sensory acceptance (odor, taste, and overall acceptance) as dependent variables. A model equation obtained from RSM showed 0.88 of R-square for odor, 0.90 for taste, and 0.95 for overall acceptance with 0.07 lack of fit in overall acceptance (P<0.05). Odor score (predicted value) was 7.21 in the saddle point. Optimal flavoring conditions for making a crab-like flavorant were as follows: addition of 0.29 g of proline, 0.63 g of glycine, 0.61 g of arginine, 0.02 g of methionine, and 1.07 g% (w/v) of fructose into SCCE with RFT (90 min at $130^{\circ}C$). Odor score obtained under optimal conditions was 7.56, which was higher than the predicted value.

• Korean Journal of Food Science and Technology
• /
• v.49 no.3
• /
• pp.286-295
• /
• 2017

This study was performed to develop a liquid flavoring material from Tenebrio molitor larva by using Aspergillus oryzae. T. molitor with 1% A. oryzae for 48 hours yielded the highest protease activity. Different salt concentrations and rice flour addition affected the fermentation characteristics for 90 days. LN (low salt, rice flour non-addition) yielded high protease activity, and total nitrogen and amino-type nitrogen contents. LN showed Glu accounting to 15.16% of the free amino acids and yielded high scores of sweet and savory taste, and overall acceptance after 90 days. Rice flour addition group showed high content of total and reducing sugars with high amylase activity, however, low salt concentration had more effect on sensory acceptance than rice flour addition had (p<0.05). All samples had total acidity <1% and LN (90) showed the highest browning index and aroma intensity, as noted from maillard reaction, as well as good sensory acceptance.

• Korean Journal of Food Science and Technology
• /
• v.41 no.6
• /
• pp.622-627
• /
• 2009

The objectives of this study were to evaluate a protease suitable for the enzymatic hydrolysis of a snow crab processing by-product (SPB) and to optimize the hydrolysis conditions using response surface methodology (RSM). The SPB was hydrolyzed at $50^{\circ}C$ and pH 7.0-7.2 to obtain various degree of hydrolysis (DH) using Flavourzyme at an enzyme/substrate (E/S) ratio of 3.0%. The reaction progress curve exhibited an initial fast reaction rate followed by a slowing of the rate. The DH was increased to 30% at 90 min with a final DH 32 to 36%. A central composite experimental design having three independent variables (reaction temperature, reaction time, and E/S ratio) with five levels was used to optimize the enzymatic hydrolysis conditions. Based on the DH data, the optimum reaction conditions for the enzymatic hydrolysis of the SPB were a temperature of $51.8^{\circ}C$, reaction time of 4 hr 45 min, and an E/S ratio of 3.8%. It was demonstrated that the enzymatic hydrolysate of SPB could be used as a flavoring agent or a source of precursors for the production of reaction flavors.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.1
• /
• pp.79-85
• /
• 2000

Proximate composition of concentrated oyster cooker effluent (COCE) was $70{\%}$ moisture, $8.55{\%}$ total nitrogen, and $18.6{\%}$ ash. Optimum conditions for enzymatic hydrolysis of COCE ($200 ml$) weve $pH 7.0{\~}7.5\;and 50{\~}60{\circ}C$ for 8 h reaction time with 0.128 U of Aspergillus oryzae PE protease(AOP), Hydrolysis of COCE led to an increase in free amino acids to 1.41 fold, with taurine comprising about $17.62{\%}$ of the total free amino acid. Fifty volatile flavor components were identified in COCE and 63 in enzyme treated COCE (HCOCE). Volatile flayer compounds we increased significantly in HCOCE when compared with untreated COCE. Results of this study might help to alleviate the current wastewater disposal problem caused by oyster cooker effluent.

• Journal of the Korean Wood Science and Technology
• /
• v.46 no.4
• /
• pp.415-422
• /
• 2018

Terpenoids have a wide range of biological functions and have extensive applications in the pharmaceutical, cosmetic, and flavoring industry. The white-rot fungus, Polyporus brumalis, is able to synthesize terpenoids via terpene synthase, which catalyzes an important step that forms a large variety of sesquiterpene products from farnesyl pyrophosphate (FPP). To improve the production of sesquiterpenes, the terpene synthase gene was isolated from Polyporus brumalis and was heterologously transformed into a Pichia pastoris strain. The open reading frame of the isolated gene (approximately 1.2 kb) was inserted into Pichia pastoris to obtain a recombinant enzyme. Five transformants were obtained and the expression of terpene synthase was analyzed at the transcript level by reverse transcription PCR (polymerase chain reaction) and at the protein level by SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Expression of the terpene synthase gene product was elevated in the transformants and as expected the molecular weight of the protein was approximately 45 kDa. These recombinant enzymes have potential practical applications and future studies should focus on their functional characterization.