Glycoside as a Flavor Precursor during Extrusion - American Chemical

Chapter 31

Glycoside as a Flavor Precursor during Extrusion 1,3

2

Shigeru Tanaka , Mukund V. Karwe , and Chi-Tang Ho 1

1

2

Downloaded by YORK UNIV on June 3, 2018 | https://pubs.acs.org Publication Date: November 30, 1993 | doi: 10.1021/bk-1994-0543.ch031

Department of Food Science and The Center for Advanced Food Technology, Cook College, New Jersey Agricultural Experiment Station, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903

The application of glycosides as flavor precursors during extrusion cooking was evaluated using phenyl-β-glucoside as a model compound. The glycoside was added to cornmeal, and the amount of phenol generated during twin-screw extrusion was measured as a function of different temperatures and screw speeds. The extrudate was extracted with methanol, followed by water-saturated butanol and quantified by HPLC analysis. The analytical results indicated that phenol could be produced from its glycoside during extrusion cooking. Extrusion temperature had more significant effects on phenol generation than screw speed. Higher temperatures, in general, resulted in more generation of phenol. Flavor generation during extrusion cooking using twin-screw extruders has recently attracted the interest of many researchers. One of the key flavor technology issues is the loss of flavors, especially those added before extrusion (72). Several studies concerning the application of the so-called "extrusion stable flavors" have been reported (3). In recent years, the importance of glycosidically-bound volatile constituents to fruit and vegetable aromas is receiving increased attention by many investigators (4-9). It has been noted by many authors that these glycosidicallybound volatiles in fruits and plant tissues will subsequently release their free aroma constituents by enzymatic and/or chemical hydrolysis and increase the yield of essential oils during fruit ripening and climatic conditions (JO). The release of free aroma compounds such as vanillin through the pyrolysis of its glycosidic precursor has been reported (77). 3

Current address: Takasago International Corporation (USA), 100 Green Street, Teterboro, NJ 07608

0097-6156/94/0543-0370$06.00/0 © 1994 American Chemical Society

Parliment et al.; Thermally Generated Flavors ACS Symposium Series; American Chemical Society: Washington, DC, 1993.

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Glycoside as a Flavor Precursor during Extrusion

371

Glycosidically-bound aroma compounds may possibly be used as stable flavor precursors in extruded foods. The thermal and mechanical energy applied during extrusion may break down the glycoside linkage of the added precursors and generate the desirable flavor for the extruded products. Therefore, the objective of this research is to study the generation of phenol from its β-glucoside, which is added to cornmeal before twin-screw extrusion, and to evaluate the effects of the extrusion conditions on its formation.


Experimental Extrusion Conditions. Degerminated com meal (CC 400, Lauhoff Grain Co., Danville, IL) was extruded using a twin-screw extruder (ZSK-30, Werner & Pfleider, Ramsey, NJ) with two circular opening dies (each diameter was 3 mm). Table I shows the screw configurations used for this study. Three extrusion temperatures (165°C, 175°C and 185°C at the die plate), and three screw speeds (300, 400 and 500 rpm) were used to evaluate the effects of extrusion conditions on the formation of three phenolic acids from their glycosidic precursors. Water was fed to the com meal by a metering pump (U.S. Electric Co., Milford, CT) from a barrel opening adjacent to a volumetric feeder (K-Tron series 7100, K-Tron Corp., Pitman, NJ). For all experiments, the moisture content of the com meal was maintained at 18% during extrusion by determining its moisture content beforehand. The feed rate of the com meal at 18% moisture content was 300 g/min. Phenyl-β-glucoside. Phenyl-P-glucoside (3.5 g, Sigma Chemical Co., St. Louis, MO) was mixed with 0.04 g of red dye (FD&C Red No. 40, Hilton Davis Co., Cincinnati, OH) and formed into a pellet by a hydraulic press. The pellets were added to the com meal through the opening at the connection between the feeder and the barrel after the stable extrusion outputs were observed. Extraction of Phenol and Phenyl-P-glucoside - Determination of Residence Time Distribution. The extruded com meal was collected every 15 seconds for 3.35 minutes, starting from the moment the phenyl-P-glucoside pellet was added. Each extrudate sample was powdered by a Waring blender (Dynamics Corporation of American, New Hartford, CT) and passed through sieves. The powder passed through a sieve with 0.589 mm openings, but was held by the 0.180 mm openings, and was collected. Using the standard A O A C method, the moisture content of the powder was measured before the phenolic quantifications were determined. For all experimental extrusion conditions, preliminary HPLC analysis was performed after methanol extraction. After it was determined that the majority of added phenyl-P-glucoside was converted to phenol within 0-60 seconds of the sampling period, the powdered extrudates were combined. Next, a total of 20 g (dry weight basis) of the powdered material was made from the combined material to evaluate extrusion conditions.


372

THERMALLY GENERATED FLAVORS

Table L Elements Drive end 1* 1* 1*


1* 1* 2* 1* 2* 1* 2* 1* 1* 2* 1* 1* 1* 2* 2* 1* Die plate

Screw Configuration for ZSK-30 Extrader

Screw Type

Pitch/Length (mm)

No.

Right-handed Right-handed Right-handed Igel (Mixing) Right-handed Igel (Mixing) Right-handed Right-handed Right-handed Right-handed Right-handed Right-handed Left-handed Right-handed Right-handed Left-handed Right-handed Right-handed Right-handed Left-handed Right-handed

42/21 42/42 42/21 42/42 28/28 42/42 28/28 45 degree 28/14 45 degree 20/20 45 degree 20/10 20/10 45 degree 20/10 20/10 14/14 45 degree 45 degree 14/14

χ 1 χ 2 χ 2 χ 1 χ 3 χ 1 χ 2 χ 1 χ 3 χ 1 χ 5 χ 1 χ 1 χ 5 χ 1 χ 1 χ 2 χ 2 χ 1 χ 1 x6

(5 discs)/28 (5 discs)/14 (5 discs)/20

(5 discs)/20

(5 discs)/14 (5 discs)/14

1* : A l l transition elements (1*) are double-flighted screws 2* : Kneading blocks

Extraction to Evaluate Extrusion Conditions. Twenty g (dry weight basis) of the powder was mixed with 300 mL of methanol (A452, Fisher Scientific, Pittsburgh, PA) and stored overnight at room temperature. The mixture was filtered using Whatman No. 2 paper (Whatman, International, Ltd., Maidstone, England), and the extract was evaporated to 3 mL by a rotary evaporator (Flash evaporator, Buchler Instruments, Fort Lee, NJ) for HPLC analysis. The residual powder after methanol extraction was further extracted by adding 200 mL of water saturated with /i-butanol (Fisher Scientific, Pittsburgh, PA). The mixture was agitated for 6 hr at 75° C in a shaker apparatus (New Brunswick Scientific, Edison, NJ). After filtration under vacuum, the extract was concentrated to 12 mL for further HPLC analysis.


31. TANAKA ET AL.


373

H P L C Analysis. HPLC conditions for the quantification of phenolic compounds were based on those reported by Wu et al. (8). A solvent delivery system (Model 6000A) and an absorbance detector (Model 440, Waters Associates, Milford, MS) with a 280 nm wavelength kit were used. The column was a Parti Sphere C reverse phase column (Whatman, Inc., Clifton, NJ). An aliquot of the concentrated extracts was injected into the column using an injector with a 20 loop for each analysis. The mobile phase consisted of 0.05 M sodium acetate (pH = 4.0):methanol (80:20) and its flow rate was 0.8 mL/min. Quantification was done by comparing the integrated peak area from the extracts with those of known standards using an integrator (Model 4270, Varian Associates, Walnut Creek. CA). The phenol was purchased from Mallinckrodt Chemical Works (St. Louis, MO). A typical retention time for the phenol and phenyl-3-glucoside were ca. 18 and 8 minutes, respectively. The presence of phenol in the methanol extract was confirmed by HPLC-mass spectrometric analysis. No phenols were observed in the extracts from the unextruded com meal by either methanol or water-saturated w-butanol.


1 8

Color Measurement The color of the powder made from extruded com meal was measured by absorbance of the methanol extract at 499.2 nm using a spectrophotometer (Model U-3110, Hitachi Instruments, Inc., Tokyo, Japan).

Results and Discussion Distribution of Phenyl-(3-glucoside and Phenol during Extrusion. Because a large quantity of material is required to perform the experiments on a twin-screw extruder, it is difficult to study a particular chemical reaction, especially when the chemicals are expensive. In order to solve this problem, we mixed the expensive phenyl-P-glucoside with the intensely colored red #40 dye, which was pressed into a pellet. The pellet was added into the extruder when the desired extrusion conditions for the com meal were met. Distribution of phenyl-P-glucoside in the extrudates (at 165°C and 300 rpm) which were collected every 15 seconds from the dies after the pellet was added is shown in Figure 1. The results indicate that the majority of the glucoside added was distributed within 1 minute. In the case of the extrudate processed under 185°C and 500 rpm, a substantial distribution of phenyl-P-glucoside was observed between 0 and 15 seconds (Figure 2). In both cases, all the extracted phenol were observed within these periods (Figure 3). It would be interesting to observe a relationship between the dye and the phenyl-p-glucoside in terms of residence time behavior during extrusion. Color intensity measured by absorbance showed a good linear relationship (Figure 4). The results indicate the dye and glucoside would behave almost identically during extrusion, even though they were not chemically attached to each other.


374


Extrudate Weight (g, D.W.)

Phenyl-Glucoelde (ppm, D.W.)

% #

*

400 H


200

0-16

16-30 30-46

46-60

60-76

76-90 106-120120-136136-160

Sampling Time (sec.) I Phe-Qlu

*

Extrudate Weight (g)

Figure 1. Distribution of glucoside in sample extruded at 165°C and 300 rpm.

1600

Extrudate Weight (g, D.W.)

Phenyl-Gluooelde (ppm, D.W.)

1400-

70 -60

1200-

-50

1000

-40

B00 -30 600 -20

400

10

200

0

0 0-16

16-30 30-46

46-60

60-76

76-90 106-120120-136136-160

Sampling Time (sec.) I Phe-Qlu

*

Extrudate Weight (g)

Figure 2. Distribution of glucoside in sample extruded at 185°C and 500 rpm. Parliment et al.; Thermally Generated Flavors ACS Symposium Series; American Chemical Society: Washington, DC, 1993.

31. TANAKA ET AL.


Phenol Cone, (ppm) Extrusion Conditions 0


•1166 C/300 rpm

V ///////// 0-15

15-30 30-45 45-60 60-75 75-90

E 2 i86°C/500 rpm

/ 105

//////////// 120

135

150

Sampling Time (sec.) Figure 3. Phenol distribution (ppm in extrudates, dry weight basis)

Figure 4. Correlation between phenyl-glucoside concentration and absorbance of the methanol extract.


375


376


Formation of Phenol from Phenyl-β-glucoside during Extrusion. Figure 5 shows changes in the phenol concentration of the extrudates due to the difference in the extrusion conditions. Differences in the quantification results from methanol and butanol extractions showed that a majority of phenol formed was extracted by methanol. Generally, the concentration of phenol increased as the extrusion temperature and screw speed were increased. The highest concentration (6.96 ppm, dry base) of phenol was observed in the extrudate at 185°C with a screw speed of 400 rpm, and the lowest (0.37 ppm) under the conditions of 165°C and 300 rpm combination. As shown in Figure 5, however, the concentration of phenol extruded at 185°C and 500 rpm decreased. This might result from the loss to the atmosphere through evaporation of the steam at the die opening, and the higher extrusion conditions might have favored the dissipation. Actually, the odor of phenol was detected under the higher extrusion conditions mentioned above. The effects of extrusion (die) temperature and screw speed on the concentration of phenol were analyzed by regression analysis using an SAS package. The results indicated that the extrusion temperature exerted a significant (p = 0.01) effect on the formation of phenol from the glucoside, however, the screw speed showed no significant effect. The recovery of the phenyl-P-glucoside by the two solvents is shown in Figures 6, 7 and 8. It was found that the higher the extrusion temperatures and screw speeds used, more glycosides were recovered by water-saturated butanol than methanol. This might result from the difference in the degree of the entrapment of the glycosides by the extrudates formed by higher temperatures and screw speed. A recent study (72) concerning the fluorescence anisotrophy measurement of the extruded com meal described the possible involvement of phenolic acids in the formation of crosslinking among the starch-protein matrix. It indicated that this immobilization of the innate phenolic acids could be responsible for the regidification of the extruded materials. Attempts were made to calculate the conversion of extractable phenol from the glycoside by treating the extrudate with starch enzymes (amyloglucosidase, for example) to increase the recovery. However, cleavage of the glycoside in conjunction with the cleavage of the starch matrix was observed. If 90% of 3.5 g of phenyl-P-glucoside added was assumed to be distributed within the first 60 seconds, the concentration of the glucoside was estimated ca. 1.3% (dry weight) of the extrudate (185°C and 400 rpm). Since the observed concentration of phenol was 6.96 ppm (dry basis) in the extrudate, its estimated conversion (mole basis) could be 0.15%. Conclusion Formation of phenol from phenyl-P-glucoside which was added extrinsically to com meal was observed during cooking utilizing a twin-screw extruder. Evaluation of the extrusion conditions indicated extrusion temperature had a more significant effect than screw speed.


31. TANAKA ET AL.

377



ppm in Methanol Extract (D.W.)

300 rpm

400 rpm

500 rpm

Extruder Screw Speed • 1 1 6 5 °C

E 2 175 °C

E Z 3 185 °C

Figure 5. Effects of extrusion conditions on phenol concentration.

Extrusion Temp.

I Methanol Ext. (ppm)

E23 Butanol EXT. (ppm)

-r 3 1-5 Thousands

1.5 3 Thousands

165°C

175°C

1B5°C

4J5

Figure 6. Glucoside concentration in samples extruded at 300 rpm.


4.5

378


I Methanol Bet (ppm)

Extrusion Temp.

E23 Butanol EXT. (ppm)

165°C


175°C

1B5°C

4J5

3 1.5 Thousands

0

1.5 3 Thousands

4.5


I Me-OH Ext. (ppm)

Extrusion Temp.

E S 3 But-OH EXT. (ppm)

165°C

175°C

1B5 C

4J5

3

1-5

Thousands

Ο

"1

Γ"

1.5

3

Thousands



4.5

31. TANAKAETAL.

Glycoside as a Flavor Precursor during Extrusion 379

Acknowledgments We thank Dr. R. T. Rosen for LC-MS analysis. Valuable assistance by Dr. v. Karathanos regarding statistical analysis, and the extrusion experiments conducted by Mr. H. Izzo are appreciated.

Literature Cited


1. 2. 3.

4. 5. 6. 7. 8. 9. 10.

11. 12.

Parkert, P. E.; Fagerson, I. S. J. Food Sci. 1980, 45, 526-528. Chen, J.; Reineccius, G. Α.; Labuza, T.P. J. Food Technol. 1986, 21, 365383. Maga, J. A. In Thermal Generation of Aromas; Parliment, T.H.; McGorrin, R. J.; Ho, C.-T.. Eds.; ACS Symp. Ser. No. 409; American Chemical Society: Washington, D.C., 1989; pp 494-503. Wilson, B.; Strauss, C. R.; Williams, P. J. J. Agric., Food Chem. 1984, 32, 919-924. Schwab, W.; Mahr, C.; Schreier, P. J. Agric. Food. Chem. 1989, 37, 10091012. Winterhalter, P. J. Agric. Food Chem. 1990, 38, 452-455. Wu, P.; Kuo, M.-C.; Ho, C.-T. J. Agric. Food. Chem. 1990, 38, 15531555. Wu, P.; Kuo, M. C.; Zhang, K. Q.; Hartman, T. G.; Rosen, R. T.; Ho, C.T. Perfumer Flavorist 1990, 15(1), 51-53. Marlatt, C.; Ho. C.-T.; Chien, M. J. Agric. Food Chem. 1992, 40, 249-252. Williams, P. J.; Sefton, Μ. Α.; Francis, I. L. In Flavor Precursors: Thermal and EnzymaticConversions;Teranishi, R.; Takeoka, G. R.; Güntert, M., Eds.; ACS Symp. Ser. No. 490; American Chemical Society: Washington, D.C., 1992; pp 74-86. Adedeji, B. A. Ph.D. Dissertation, Rutgers University, New Brunswick, NJ, 1992. Gibson, S. M.; Strauss, G. In Phenolic Compounds in Food and Their Effects on Health I. Analysis, Occurrence and Chemistry, Ho, C.-T.; L C. Y.; Huang, M. T., Eds.; ACS Symp. Ser. No. 507; American Chemical Society: Washington, D.C., 1992; pp 248-258.

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Glycoside as a Flavor Precursor during Extrusion - American Chemical

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