Abstract SCHIRACK, ANDRIANA VAIS. The Effect of Microwave ...

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was also observed. The addition of phenylacetaldehyde caused a green/plant-like note, while the addition of guaiacol gave a darker roast character to the model as compared to the control. 2,6-dimethylpyrazine, although adding a sweet, caramel note at lower concentrations, became perceived as a sweet and rotten aroma at higher concentrations. In the tasting models, phenylacetaldehyde added a green/plant-like note at low concentrations, but created a stale/cardboardy character at higher concentrations. Guaiacol added astringency, bitterness, and more ashy and woody character to the flavor. 2,6-dimethylpyrazine added rotten notes to the flavor, and also contributed to the perception of dark roast flavor. A combination of these three compounds at their respective concentrations found in microwave blanched peanuts created an aroma profile high in dark roast character, with more astringency and tongue and throat burn, and less impact of positive characteristics such as roasted peanutty attribute. The panel agreed that the combination of phenylacetaldehyde, guaiacol, and 2,6-dimethylpyrazine each at a concentration of one standard deviation above the average concentration found in the microwave- blanched samples appeared to most closely mimic the off-flavor in microwave- blanched peanuts. The unique characters of these three compounds combine to form an off- flavor which is difficult to define. Further work must be conducted to clarify the role of 2,6-dimethylpyrazine. However, it appears that guaiacol contributes to the dark roast/burnt flavor perceived in the microwave samples, and phenylacetaldehyde is responsible for a green and cardboardy note which could be perceived as stale/floral. In the future, these compounds could be used as chemical anchors for 164
sensory panelists analyzing process samples and would aid in the identification of process-related off-flavors. Conclusion More than 200 aroma-active compounds contributed to the flavor of roasted peanuts. Maillard reaction, lipid oxidation, and thermal degradation products dominated the flavor profiles. Isolation of the compounds causing a microwave- related off-flavor in peanuts was possible through solvent extraction/SAFE, GC/O, GC/MS, threshold testing and model systems analysis. The stale/floral and ashy off- flavor in microwave-blanched peanuts was related to increased concentrations of phenylacetaldehyde, guaiacol, and 2,6-dimethylpyrazine. Increased and unfavorable levels of these compounds may have been formed through Maillard reactions and thermal degradation during the high temperatures attained during microwave blanching. These findings are important because they further explore the relative balance of the many aroma-active compounds which have been documented in peanuts, and could possibly aid in enhancing quality control for alternative processing techniques in peanut production. Acknowledgments This research was funded in part by the North Carolina Agricultural Research Service. This is paper no. --- of the Journal Series of the Dept. Food Science, North Carolina State University, Raleigh, NC 27695. The assistance of Mary Carunchia Whetstine, Lisa Oerhl Dean, Evan Miracle and Joy Wright is gratefully 165
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Abstract SCHIRACK, ANDRIANA VAIS. T
Page 3 and 4:
THE EFFEGT OF MICROWAVE BLANCHING O
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BIOGRAPHY Andriana Schirack is orig
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TABLE OF CONTENTS v Page List of Ta
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Materials and Methods..............
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Table 3 High Impact Aroma-Active Co
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CHAPTER 1: INTRODUCTION 1
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The processing parameters used duri
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educed from 35-40% moisture to 8-10
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REFERENCES Adelsberg GD, Sanders TH
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Interdependency and underlying dime
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Composition of Peanuts The structur
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and Burma. The peanut prices in the
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(w.b.) within 3 days, large quality
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cdry = Specific heat of dry seeds (
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there is no direct correlation publ
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Peanuts are commonly stored in flat
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lanching has been imitated using a
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(1999), no detrimental effects of b
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when the air is distributed from ab
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y-product (Giese, 1992). Drying is
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the material to absorb electromagne
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ε' = Relative real permittivity (d
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oils, both ε' and ε" are low and
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1969). The flavor characteristics o
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et al., 1980). Likewise, sugars pre
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n-methylpyrrole. Walradt et al. (19
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fact, Ory et al. (1992) suggested t
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Flavor Research in Other Nuts Sever
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changed with time of roasting and i
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polyunsaturated acids that have a c
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hexanal are intensified to the high
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The results of temperature stress i
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Brown et al. (1977) found that the
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exhibited the fruity fermented off-
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(Pawliszyn, 2000). Also, the elevat
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compounds eluting from microwave-he
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Table 1: Peanut Volatile Analysis b
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the identification of volatile comp
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the detector. The compounds can the
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GC-O Applications High vacuum disti
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each half was allocated into one of
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Woody/Hulls/Skins Cardboard Table 2
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Givaudan-Roure developed Quantitati
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during high temperature microwave b
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OVM Organic volatiles meter Pa Pasc
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References Abegaz EG, Kerr WL, Koeh
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odorants in high temperature cured
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17(4): 728-732. Mason ME, Waller GR
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partitioning constants and release
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Vercellotti JR, Crippen KL, Lovegre
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ABSTRACT Peanut blanching consists
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peanut moisture content from 5.5 to
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The computer monitored power output
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RESULTS AND DISCUSSION Energy Absor
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All treatments using the fan (F) ha
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Treatments 11NF, 8NF, and 5NF also
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lanchabilities as well as a longer
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microwave attain much higher temper
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REFERENCES ADELSBERG, G.D. and SAND
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TABLES AND FIGURES Table 1: Process
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Energy absorbed (kJ) 3000 2500 2000
Page 125 and 126: Temperature of peanuts (°C) 160 14
Page 127 and 128: Percent blanchability 100 90 80 70
Page 129 and 130: Maximum internal temperature (°C)
Page 131 and 132: ABSTRACT Microwave blanching of pea
Page 133 and 134: Several methods are used for blanch
Page 135 and 136: Peanuts MATERIALS AND METHODS Mediu
Page 137 and 138: Canada) on a laptop computer (Dell
Page 139 and 140: Sensory Analysis RESULTS AND DISCUS
Page 141 and 142: significantly lower final moisture
Page 143 and 144: ACKNOWLEDGMENTS Funded in part by t
Page 145 and 146: Foods and Beverages, Vol. 29, (G. C
Page 147 and 148: TABLE LEGENDS Table 1. Microwave ap
Page 149 and 150: TABLE 2. LEXICON OF PEANUT FLAVOR D
Page 151 and 152: Sweet Aromatic TABLE 4. CORRELATION
Page 153 and 154: CHAPTER 5: CHARACTERIZATION OF AROM
Page 155 and 156: Introduction The most common use of
Page 157 and 158: The objective of this study was to
Page 159 and 160: attributes which were different fro
Page 161 and 162: Volatile compounds from the solvent
Page 163 and 164: 0.25 μm df; J & W Scientific, Fols
Page 165 and 166: adjusted with the same concentratio
Page 167 and 168: characterized by the attributes of
Page 169 and 170: (E,E)-2,4-decadienal (fried/oxidize
Page 171 and 172: flavor dilution factors, nor did th
Page 173 and 174: that of the control, but only in th
Page 175: e high enough for pyrazine formatio
Page 179 and 180: References (ASTM) American Society
Page 181 and 182: Megahed MG. 2001. Microwave roastin
Page 183 and 184: Vercellotti JR, Mills OE, Bett KL,
Page 185 and 186: Table 2- Model system concentration
Page 187 and 188: 28 4-acetoxy-2,5-dimethyl- 3(2H)-fu
Page 189 and 190: Table 5 - Quantification, sensory o
Page 191 and 192: Conclusions This research investiga
Page 193 and 194: microwave technology may provide ma
Page 195 and 196: protect against colon, prostate, an
Page 197 and 198: APPENDICES 185
Page 199 and 200: SAFE (3 SAFE's can be done in 1 day
Page 201 and 202: 2. Turn off waterbath. 3. Turn off
Page 203 and 204: 5. Filter through a third sodium su
Page 205 and 206: contamination, and run a blank on t
Page 207 and 208: AC nutty/burnt 975 1.5 NB cabbage/g
Page 209 and 210: AC oxidized 1289 1.5 NB dusty/nutty
Page 211 and 212: NB brothy 1612 3.5 NB honey/hay 161
Page 213 and 214: Table 2: Aroma-Active Compounds in
Page 215 and 216: AC cedar 1081 3.0 AC burnt sugar/nu
Page 217 and 218: AC brothy 1350 2.0 NB garlic 1352 5
Page 219 and 220: NB fruity/floral 1670 3.0 NB rosy 1
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