Characteristic coloring curve for white bread during baking.

The effect of heating conditions on the crust color formation was investigated during the baking of white bread. The surface temperatures were monitored with thermocouples attached to the inside surface of the loaf pan cover. The trace of the surface color in the L(*)a(*)b(*) color coordinate system is defined as the characteristic coloring curve. The overall baking process was classified into the following four stages based on the characteristic coloring curve: i) pre-heating (surface temperature < 110 °C), ii) Maillard reaction (110-150 °C), iii) caramelization (150-200 °C), and iv) over-baking (surface temperature>200 °C). A linear relationship was observed between the L(*) decrease and the increase in weight loss of a sample at each oven air temperature. The L(*) value appeared to be suitable as an indicator to control the surface color by baking conditions.

Odorant transfer characteristics of white bread during baking.

The potent odorants in the crust and crumb of white bread were identified and quantified by gas chromatography-mass spectrometry and gas chromatography/olfactometry. The weight loss ratio of the samples baked at 220 °C was controlled in the range of 0-28%. The odorants were classified into 5 types by the transfer characteristics: i) All amounts of odorant transferred from the crust to external space (type-I). ii) All transferred from the crust to the crumb and external space (type-II). iii) Certain amount remaining in the crust and the rest transferred to the crumb and external space (type-III). iv) All transferred from the crumb to external space (type-IV). v) Certain amount remaining in the crumb and the rest transferred to the crust and external space (type-V). The odorants of type-IV were not apparent after the crust had formed. The results indicate that the crust could be a barrier to prevent the odorants from being transferred to external space.

Analysis of Volatile Compounds from Chili Peppers and Characterization of Habanero (Capsicum chinense) Volatiles.

The Habanero pepper is characterized by its strong pungency and fruity aroma. The aim of the present study was to extract the volatile compounds of Habanero peppers, using solvent extraction and solvent-assisted flavor evaporation (SAFE) methods, and to analyze them using gas chromatography-mass spectrometry (GC-MS). The analysis detected 66 volatile compounds, including 6-methyl-(E)-4-heptenyl 3-methylbutanoate 1, which was reported previously, and 6-methyl-(E)-4-heptenyl 2-methylpropanoate 2, the corresponding butanoate 3, 2-methylbutanoate 4, and 6-methyl-(E)-4-heptenol 5, which were found in both Habanero and other peppers. 6-Methyl-(E)-4-heptenyl 3-methylbutanoate 1 and related compounds were synthesized. Furthermore, principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the volatile profiles generally grouped the pepper samples by species and indicated that Habanero peppers are characterized by the presence of 6-methyl-(E)-4-heptenyl esters.

Isolation and Identification of a Volatile Compound in Habanero Pepper (Capsicum chinense).

A volatile compound was isolated from the fruit of Habanero pepper (Capsicum chinense) and related varieties and identified as 6-methyl-(E)-4-heptenyl 3-methylbutyrate by 1H and 13C NMR spectroscopy and two-dimensional NMR experiments, including HMQC, HMBC, and 1H-1H COSY. The compound has a retention index of 1387 and is one of the major volatile compounds in Habanero pepper. This compound would be useful as a new flavor.

Effects of Manufacturing Processing Conditions on Retronasal-Aroma Odorants from a Milk Coffee Drink.

To develop a ready-to-drink (RTD) milk coffee that retains the original coffee flavor, the effects of manufacturing processing conditions on retronasal-aroma (RA) odorants were investigated by gas chromatography-olfactometry (CharmAnalysis™) using an RA simulator (RAS). Twenty-nine of 33 odorants detected in the RAS effluent (RAS odorants) were identified. The detected odorants were classified into 19 odor-description groups. The total odor intensity (charm value, CMV) of all coffee RAS odorants decreased approximately 68% following pH adjustment, whereas the total CMV increased 6% to 7% following ultra-high-temperature sterilization. The total CMV ratio (about 83%) of the milk coffee produced using a new blending-after-sterilization (BAS) process without pH adjustment of the coffee was greater than that (approximately 56%) prepared using a conventional blending-before-sterilization (BBS) process with pH adjustment. In BAS-processed milk coffees, the total CMV ratio (91%) with infusion (INF)-sterilized reconstituted milk (r-milk) was greater than that (83%) of plate (PLT)-sterilized r-milk. Principal component analysis of odor-description CMVs indicated that the effect of coffee pH adjustment on odor characteristics was greater than that of sterilization, that BAS and BBS samples differed, and that BAS milk coffee prepared using INF sterilization was more similar to homemade milk coffee (blending unsterilized coffee without pH adjustment with PLT-sterilized milk) than milk coffee prepared using PLT sterilization. In conclusion, the BAS process using INF sterilization is superior for manufacturing RTD milk coffee that retains odor characteristics similar to targeted homemade milk coffee. PRACTICAL APPLICATION: Ready-to-drink milk coffee beverages produced using conventional blending-before-sterilization methods do not retain their original coffee flavor following adjustment of the pH of the coffee during manufacturing. The use of newly developed blending-after-sterilization methods, by contrast, produces ready-to-drink milk coffee with an aroma more similar to that of homemade milk coffee, as demonstrated using an analytical system for characterizing food product aromas. The blending-after-sterilization process is now being used in Japan to produce ready-to-drink milk coffee beverages.

Effects of Processing Conditions During Manufacture on Retronasal-Aroma Compounds from a Milk Coffee Drink.

To develop a ready-to-drink (RTD) milk coffee retaining the original coffee flavor, the effects of processing conditions during manufacture on retronasal-arma (RA) compounds from the milk coffee were investigated by gas chromatography-mass spectrometry using an RA simulator (RAS). Thirteen of 46 detected compounds in the RAS effluent (RAS compounds) decreased significantly following pH adjustment of coffee (from pH 5.1 to 6.8) and 5 compounds increased. RAS compounds from coffee tended to decrease through the pH adjustment and subsequent sterilization. Significantly higher amounts of 13 RAS compounds were released from the milk coffee produced using a blending-after-sterilization (BAS) process without the pH adjustment than from that using a blending-before-sterilization (BBS) process with the pH adjustment. In BAS-processed milk coffee, significantly lower amounts of 8 high-volatility compounds and 1H-pyrrole were released from coffee containing infusion-sterilized (INF) milk than from coffee containing plate-sterilized (PLT) milk, whereas 3 low-volatility compounds were released significantly more from coffee using PLT milk. Principal component analysis revealed that the effect of the manufacturing process (BAS, BBS, or homemade (blending unsterilized coffee without pH adjustment with sterilized milk)) on milk coffee volatiles was larger than that of the sterilization method (INF or PLT) for milk, and that the sterilization method could result in different RAS volatile characteristics in BAS and homemade processes. In conclusion, a BAS process was found to be superior to a BBS process for the manufacture of an RTD milk coffee that retains volatile characteristics similar to that of a homemade milk coffee. PRACTICAL APPLICATION: Ready-to-drink (RTD) milk coffee manufactured using the conventional blending-before-sterilization process does not retain its original coffee flavor due to pH adjustment of the coffee during the process. The new blending-after-sterilization (BAS) process enabled the production of RTD milk coffee whose volatiles are closer to that of homemade milk coffee, as demonstrated by the results of RAS-GC-MS analysis. The BAS process has already been applied to the manufacture of RTD milk coffees in Japan.

Analysis of volatile compounds released during the grinding of roasted coffee beans using solid-phase microextraction.

A dynamic solid-phase microextraction (SPME) method to sample fresh headspace volatile compounds released during the grinding of roasted coffee beans was described and the analytical results using gas chromatography/mass spectrometry (GC/MS) and GC/olfactometry (GC/O) were compared to those of the conventional static SPME sampling methods using ground coffee. Volatile compounds released during the grinding of roasted coffee beans (150 g) were obtained by exposing the SPME fiber (poly(dimethylsiloxane)/divinylbenzene, PDMS/ DVB) for 8 min to nitrogen gas (600 mL/min) discharged from a glass vessel in which the electronic coffee grinder was enclosed. Identification and characterization of volatile compounds thus obtained were achieved by GC/MS and GC/O. Peak areas of 47 typical coffee volatile compounds, separated on total ion chromatogram (TIC), obtained by the dynamic SPME method, showed coefficients of variation less than 5% (n = 3) and the gas chromatographic profile of volatile compounds thus obtained was similar to that of the solvent extract of ground coffee, except for highly volatile compounds such as 4-hydroxy-2,5-dimethyl-3(2H)-furanone and 4-ethenyl-2-methoxyphenol. Also, SPME dilution analysis of volatile compounds released during the grinding of roasted coffee beans showed linear plots of peak area versus exposed fiber length (R (2) > 0.89). Compared with those of the headspace volatile compounds of ground coffee using GC/MS and GC/O, the volatile compounds generated during the grinding of roasted coffee beans were rich in nutty- and smoke-roast aromas.

Kinetic changes in glucosinolate-derived volatiles by heat-treatment and myrosinase activity in nakajimana (Brassica rapa L. cv. nakajimana).

Nakajimana (Brassica rapa L. cv. nakajimana), of the family Brassicaceae, is a traditional vegetable in Japan. Three isothiocyanates and five cyanides in the leaves of nakajimana were identified by gas chromatography (GC) and GC-mass spectrometry (GC-MS), and their kinetic changes using heat-treatment (temperature and time) were investigated. In addition, myrosinase activity of extracts prepared from fresh nakajimana leaf was determined. In crushed heat-treated leaves of nakajimana (70 °C for 30 s), formation of isothiocyanates and myrosinase activity increased, whereas formation of 1-cyano-3,4-epithiobutane and 1-cyano-4,5-epithiopentane decreased. Heat-treatment can significantly alter the content of potentially beneficial compounds in nakajimana, and ingestion of suitable isothiocyanates for human health may be better facilitated by mild boiling.