• Journal of Nutrition and Health
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• v.8 no.4
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• pp.33-37
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• 1975

This investigation was designed to determine the influence of drying methods on the free amino acids and free sugars in red pepper and to study the browning mechanism of brown-colored red pepper. Three different drying methods were employed: 1) Sun-drying at $25{\sim}28^{\circ}C$ for 15 days, 2) Drying in oven at $60^{\circ}C$ for 49 hours, and 3) Drying in oven at $90^{\circ}C$ for 8 hours. Dried and ground peels were used for the analysis of free amino acids and free sugars. The results were as follows; 1. Sixteen kinds of amino acids i.e. asparagine, methionine, and cystine etc. were identified. Total amino acid content of the sun-dried sample was not different from that of the fresh sample, but the samples dried at $60^{\circ}C$ and $90^{\circ}C$ in the oven were decreased to 24.9% and 67.4% respectively. Of amino acids identified, methionine, lysine and aspartic acid were decreased in all treatments. Especially, methionine ana aspartic acid were decreased rapidly to 71.8% and 73.3% , respectively. 2. Three kinds of free sugars i.e. glucose, fructose and sucrose were identified. The total content of free sugars was significantly decreased in each treatment. Among the reducing sugars, glucose was rapidly decreased; 65.9% for the glucose of sample dried at $90^{\circ}C$ in the oven. 3. At the higher drying temperature, the darker red color was found. Brown-color appeared at $90^{\circ}C-drying$ showed appreciable losses in carotenoid content, but the major color seems to be due to the large increase in browning compounds. 4. It was assumed that increased browning compounds of red pepper were due to the Maillard reaction which is a nonenzymatic browning process.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.11-15
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• 1977

Brownish discoloration develops very rapidly in the storage of dried oyster. This undesirable browning is mainly caused by the series of reactions of sugar-amino condensation, enzymatic oxidation of tyrosine and/or the oxidative rancidity of lipids in the tissue of oyster. Sulfites are commonly used as inhibitors for Maillard type browning reactions in agricultural products. The inhibitory effect of sulfite treatment on canned oysters was also confirmed in some investigations. The results suggested that sulfites not only work on blocking tile amadori rearrangement but also on the reduction of free tyrosine which retards the progress of enzymatic oxidation of tyrosine tyrosinase. In this paper, the effect of sodium sulfite treatment on the reduction of reducing sugar and free tyrosine as a function i)f browning inhibition in oyster was tested and other treatment with glucose-oxidase and yeast were also applied. In preparation of samples, fresh oysters were soaked in sodium sulfite solution by various concentration for different treating times, washed in running water to remove the sulfite residue, and finally dried in the shade. In the result, the treatment of sodium sulfite was certainly effective on the reduction of both free tyrosine and reducing sugars in fresh oyster. The best results were obtained by the treatment of 0.5M sodium sulfite solution for 60 minutes each for soaking and washing. Treatment with, glucose-oxidase and yeast solutions, however, did appear somewhat effective but it required so much time for a certain effect that it seemed not practically applicable.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.3
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• pp.458-465
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• 2011

Response surface methodology (RSM) was applied to optimize substrate conditions of ribose and hydrolyzed wheat gluten solution for Maillard reaction. Independent variables were NaCl concentration of hydrolyzed wheat gluten ($X_1$), concentration of ribose ($X_2$) and concentration of hydrolyzed wheat gluten ($X_3$), while the dependent variables of the central composite design (CCD) were browning index (absorbance 420 nm), DPPH radical scavenging activity (DF) and sensory preference (score). Optimum substrate conditions at $140^{\circ}C$, 30 min reaction were 3% NaCl concentration of hydrolyzed wheat gluten, 6.2% concentration of ribose and 13.27% concentration of hydrolyzed wheat gluten. The coefficients of determination ($R^2$) were 0.975, 0.960 and 0.854, the model fit was very significant (p<0.001). DPPH radical scavenging activities and sensory preferences were predicted as 700 (DF) and 8.42 (score), respectively. The model solution increased more browning and DPPH radical scavenging activities with increasing ribose and hydrolyzed wheat gluten concentration. Especially hydrolyzed wheat gluten concentration was the most influential factor, while NaCl concentration of hydrolyzed wheat gluten hardly affected the responses. Sensory preference was increased with rising wheat gluten concentration and decreasing NaCl concentration of hydrolyzed wheat gluten.

• Food Science of Animal Resources
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• v.40 no.3
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• pp.350-361
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• 2020

Quality control of meat products is one of the main concerns of consumers, governmental control authorities, and retailers. The purpose of this study was to employ ribose-induced Maillard reaction in detection of meat adulteration and differentiation of fresh-chilled from frozen-thawed minced veal. The browning intensity was assessed through measuring the absorbance at 420 nm with a spectrophotometer as well as the direct analysis of the color and pH. The results showed that CIE b*, CIE a*, and A_420* values in the extract of fresh-chilled veal were significantly (p<0.05) higher than frozen-thawed samples. The extract of frozen meat samples stored at -18℃ became significantly darker and more yellowish compared to -4℃. The results showed that the A_420* value in the frozen-thawed veal stored at -4℃ and -18℃ was reduced by approximately 17.22±3.53% and 11.68±2.49%, respectively, compared with fresh-chilled veal. The findings also showed that the storage temperature of minced veal and the heating time in this reaction had a significant effect on all tested variables (p<0.0001). The proposed method can be considered as an easy, quick, and inexpensive test for differentiating between the fresh-chilled and frozen-thawed minced veal.

• Food Science of Animal Resources
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• v.44 no.3
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• pp.662-683
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• 2024

Thai-Native×Anglo-Nubian goat meat cooked by grilling (GR), sous vide (SV), and microwave (MW), was compared to fresh meat (Raw) in terms of flavor development. Non-volatile [i.e., free amino acids, nucleotide-related compounds, taste active values (TAVs) and umami equivalency, sugars, lipid oxidation, Maillard reaction products] and volatile compounds, were investigated. Notably, inosine monophosphate and Glu/Gln were the major compounds contributing to umami taste, as indicated by the highest TAVs in all samples. Raw had higher TAVs than cooked ones, indicating that heat-cooking removes these desirable flavor and taste compounds. This could be proportionally associated with the increase in aldehyde, ketone, and nitrogen-containing volatiles in all cooked samples. GR showed the highest thiobarbituric acid reactive substances (1.46 mg malonaldehyde/kg sample) and browning intensity (0.73), indicating the greatest lipid oxidation and Maillard reaction due to the higher temperature among all cooked samples (p<0.05). In contrast, SV and Raw exhibited similar profiles, indicating that low cooking temperatures preserved natural goat meat flavor, particularly the goaty odor. The principal component analysis biplot linked volatiles and non-volatiles dominant for each cooked sample to their unique flavor and taste. Therefore, these findings shed light on cooking method selection based on desirable flavor and preferences.

• Applied Biological Chemistry
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• v.29 no.2
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• pp.190-197
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• 1986

In order to develop a simple and effective method for determining the rate of the Maillard reaction in non-fat dry milk, the carbon dioxide content of the headspace as an indicator were used and the amount of correlation between $CO_2$ content and brown color development were determined by the gas chromatograph. There is a high correlation between brown color and $CO_2$ content. The use of gas chromatography to analyze the $CO_2$ in the headspace of samples is a quick, simple and effective method of monitoring the Maillard reaction. Volatile concentration increases with storage time and varies inversely with oxygen content. Lysine is more effective than glucose in catalyzing the Maillard reaction. Product samples can be stored at $55^{\circ}C$ and $68^{\circ}C$ to accelerate the rate of the Maillard reaction and shorten testing period, but product stored at $75^{\circ}C$ is degraded too rapidly to be of any real use.

• Korean Journal of Food Science and Technology
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• v.13 no.4
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• pp.273-282
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• 1981

The antioxidant actilvity of ethanol-extracts (M-2 and M-30), which had been obtained from a Maillard-type browning mixture after 2 and 90 hr browning, and BHA, BHT, TBHQ, and ascorbyl palmitate It·as investigated in soybean oil and soybean oil-water emulsion systems. The activity of the extracts and antioxidants was estimated by comparing the POV and TBA value development of the corresponding substrates with that of controls. The substrates and controls were stored at $45.0{\pm}0.5^{\circ}C$ for 25 days. The activity of the extracts (10 ml each) and antioxidants (0.02%) based mainly on the POY development of the corresponding anhydrous substrates was, in decreasing order, as follows ; As. palmitate, TBHQ > M-30, M-2 > BHT, BHA The actilvity of the extracts and antioxidants in tile oil-water emulsion substrates was, in decreasing order, as follows : As. palmitate > M-30, M-2 > BHT, TBHQ, BHA The activity of the extracts appeared to be more effective in the oil-water emulsion system than in the anhydrous system, and it f·as greater than that of the phenolic antioxidants such as BHA, BHT, and TBHQ in the oil-water emulsion system.

• Applied Biological Chemistry
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• v.28 no.4
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• pp.261-270
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• 1985

This study was carried out he effects of water activity on the nonenzymatic browning reactions of dry milk powders. Samples (Dry Whole Milk DWM, Nonfat Dry Milk NFDM) stored at $55^{\circ}C$ were analyzed for $O_2,\;CO_2$ and $H_2O$ by Gas chromatographic method. The brown color which developed from the Maillard reaction was also measured by a reflective spectrophotometer. And linear regression equations and the correlation coeffcients were determined for $O_2,\;CO_2$ and brown color vs. storage, and the results are as follows. The amount of brown and off-flavor development increase as the water activities increase about 0.44 Aw during storage. Both DWM and NFDM milk products show a plateau in water absorption between the 0.33 and 0.44 water activities. DWM produced more browning than NFDM which may be partially due to the carbonyl amine reaction. The $CaCl_2$ solution may exude a water activity lower than 0.44 and varies greatly with temperatures. Oxygen is depleted as brown color development.

• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.306-312
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• 2008

This study investigated the influence of pH on the color development of melanoidins formed from amino acid enantiomer model systems. For this, the color development was evaluated by measuring browning at 420 nm and color measurements by spectrophotometry and colorimetry. The browning and browning index showed no difference according to the type of amino acid enantiomers, while that formed from the D-Asn system was the only difference according to pH level. The tristimulus value of melanoidins formed from all model systems was located on a dominant wavelength of 475 nm, the blue zone of the diagram. In addition, the $L^*$, $a^*$, $b^*$, $C^*_{ab}$ values, and ${\Delta}E^*$ index on the basis of the type of amino acid enantiomers, the differences were markedly found at pH 4.0. At pH 7.0, significantly differences were found in the $L^*$, $a^*$, $b^*$ values, and ${\Delta}E^*$ index and not in the case of the lysine enantiomers. In addition, at pH 10.0, the differences were found in the $a^*$ and $b^*$ values from the lysine enantiomers and $C^*_{ab}$ value from the asparagine enantiomers. Therefore, the color development of melanoidins was influenced by the type of amino acid enantiomers and pH levels. Especially, it is thought that the $a^*$ and $b^*$ values can be used to explain the differences among the amino acid enantiomers in the color development of melanoidins.

• Korean Journal of Food Science and Technology
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• v.25 no.3
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• pp.220-224
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• 1993

Antioxidative activities of brown materials extracted from the three kinds of roasted coffee beans by water were examined. Antioxidative activity was assessed by the AOM at $120^{\circ}C$ and the oven test at $60^{\circ}C$ on lard. The brown materials of them showed the considerable antioxiant activity. The brown materials of Colombian coffee beans were more effective than those of Robusta or Brazil beans. The antioxidative activities of brown materials from Colombian coffee beans roasted at $210^{\circ}C$ increased in proportion to the browning intensity up to 16 minutes of roasting time, but the antioxidant activities of the brown materials upon further roasting time decreased gradually. In changes of extraction temperature from $30^{\circ}C\;to\;180^{\circ}C$ on the coffee beans roasted at $210^{\circ}C$ for 16 minutes, the antioxidative activities of brown materials did not change as the extraction temperature increased to $180^{\circ}C$. The antioxidative activities of the coffee extracts were thought to be caused by browning reaction materials produced during the roasting process only.