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

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of ethanol (with possible accompaniment of methylbutanol and 2,3-butanediol), and those off-flavors caused by external contamination such as limonene, antioxidants, or insecticides (Ory et al., 1992). The main sources of off-flavors in peanuts may be lipid oxidation and anaerobic respiration due to temperature abuse. Flavors Due to Lipid Oxidation Lipid oxidation is one of the leading causes of off-flavors in raw and roasted peanuts, due to a high content of peanut lipids that contain unsaturated fatty acids (Warner et al., 1996; Lee et al., 2002). Oxidation of the fatty acids in peanut oil can be caused by light, heat, air, metal contamination, or microorganisms (Ory et al., 1992). Oil composition is crucial to oxidation rates and by-product formation. When evaluating fatty acid composition on product quality, a higher percentage of oleic acid, low percentage of linoleic acid, a high oleic/linoleic acid ratio, and low iodine value are associated with better oil stability and longer shelf-life of peanuts (Jambunathan et al., 1993). In a study examining peanuts from US, China, and Argentina, Sanders et al. (1992) found that US peanuts had consistently higher tocopherol content, lower free fatty acids and peroxide value, as well as lower copper and iron content. In addition, US peanuts had higher oleic:linoleic acid ratios, showing the influence of these factors on oxidative reactions and shelf life. Lipid oxidation has been correlated with factors such as water activity, relative humidity, and especially oxygen concentration in the environment (Labuza, 1971). However, the chief causes of lipid oxidation are enzymes such as lipoxygenase or lipase (Sanders et al., 1993). Lipoxygenase is specific for 48
polyunsaturated acids that have a cis-cis 1, 4 pentadiene structure such as linoleic and linolenic acids (Ory et al., 1992). Lipoxygenases activate oxygen to produce hydroperoxides at the allylic carbon in polyunsaturated fatty acids, and conjugated dienes can be subsequently made by rearrangement. Hydroperoxides subsequently break down into alcohols, alkanes, ketones and aldehydes which can be the source of off-flavors in the peanut. Oxidation by enzymes such as lipoxygenase is likely at locations of cell membrane disruption, as reactants previously separated become mixed and available for reaction (Ory et al., 1992). When these enzymes are inactivated by high temperatures during roasting, autoxidation becomes the principle source of lipid breakdown (Lee et al., 2002). Although all enzymes are denatured during roasting, some enzymes such as peroxidase, which contains iron, and polyphenoloxidase, which contains copper, can become pro-oxidants after denaturation (Ory et al., 1992). Transition metals such as iron and copper can promote lipid oxidation in peanuts by abstracting hydrogen from unsaturated fatty acid to make a radical, or by indirectly generating reactive oxygen species (Sanders et al., 1995). Lipid oxidation can be identified using chromatographic analysis of the samples. Regular lipid oxidation in raw or roasted peanuts is indicated by hexanal and/or hexanol in high concentrations, and when present at levels greater than 2 ppm, these can be detected by taste panelists (Ory et al., 1992). The monohydroperoxides that are formed from linoleate oxidation are precursors for volatile decomposition products such as nonanal, octanal, decanal, and hexanal, and the most predominant of these is hexanal (Min et al., 1989). Both the quality 49
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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
Page 9 and 10: Materials and Methods..............
Page 11 and 12: Table 3 High Impact Aroma-Active Co
Page 13 and 14: CHAPTER 1: INTRODUCTION 1
Page 15 and 16: The processing parameters used duri
Page 17 and 18: educed from 35-40% moisture to 8-10
Page 19 and 20: REFERENCES Adelsberg GD, Sanders TH
Page 21 and 22: Interdependency and underlying dime
Page 23 and 24: Composition of Peanuts The structur
Page 25 and 26: and Burma. The peanut prices in the
Page 27 and 28: (w.b.) within 3 days, large quality
Page 29 and 30: cdry = Specific heat of dry seeds (
Page 31 and 32: there is no direct correlation publ
Page 33 and 34: Peanuts are commonly stored in flat
Page 35 and 36: lanching has been imitated using a
Page 37 and 38: (1999), no detrimental effects of b
Page 39 and 40: when the air is distributed from ab
Page 41 and 42: y-product (Giese, 1992). Drying is
Page 43 and 44: the material to absorb electromagne
Page 45 and 46: ε' = Relative real permittivity (d
Page 47 and 48: oils, both ε' and ε" are low and
Page 49 and 50: 1969). The flavor characteristics o
Page 51 and 52: et al., 1980). Likewise, sugars pre
Page 53 and 54: n-methylpyrrole. Walradt et al. (19
Page 55 and 56: fact, Ory et al. (1992) suggested t
Page 57 and 58: Flavor Research in Other Nuts Sever
Page 59: changed with time of roasting and i
Page 63 and 64: hexanal are intensified to the high
Page 65 and 66: The results of temperature stress i
Page 67 and 68: Brown et al. (1977) found that the
Page 69 and 70: exhibited the fruity fermented off-
Page 71 and 72: (Pawliszyn, 2000). Also, the elevat
Page 73 and 74: compounds eluting from microwave-he
Page 75 and 76: Table 1: Peanut Volatile Analysis b
Page 77 and 78: the identification of volatile comp
Page 79 and 80: the detector. The compounds can the
Page 81 and 82: GC-O Applications High vacuum disti
Page 83 and 84: each half was allocated into one of
Page 85 and 86: Woody/Hulls/Skins Cardboard Table 2
Page 87 and 88: Givaudan-Roure developed Quantitati
Page 89 and 90: during high temperature microwave b
Page 91 and 92: OVM Organic volatiles meter Pa Pasc
Page 93 and 94: References Abegaz EG, Kerr WL, Koeh
Page 95 and 96: odorants in high temperature cured
Page 97 and 98: 17(4): 728-732. Mason ME, Waller GR
Page 99 and 100: partitioning constants and release
Page 101 and 102: Vercellotti JR, Crippen KL, Lovegre
Page 103 and 104: ABSTRACT Peanut blanching consists
Page 105 and 106: peanut moisture content from 5.5 to
Page 107 and 108: The computer monitored power output
Page 109 and 110: 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
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Temperature of peanuts (°C) 160 14
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Percent blanchability 100 90 80 70
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Maximum internal temperature (°C)
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ABSTRACT Microwave blanching of pea
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Several methods are used for blanch
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Peanuts MATERIALS AND METHODS Mediu
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Canada) on a laptop computer (Dell
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Sensory Analysis RESULTS AND DISCUS
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significantly lower final moisture
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ACKNOWLEDGMENTS Funded in part by t
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Foods and Beverages, Vol. 29, (G. C
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TABLE LEGENDS Table 1. Microwave ap
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TABLE 2. LEXICON OF PEANUT FLAVOR D
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Sweet Aromatic TABLE 4. CORRELATION
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CHAPTER 5: CHARACTERIZATION OF AROM
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Introduction The most common use of
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The objective of this study was to
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attributes which were different fro
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Volatile compounds from the solvent
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0.25 μm df; J & W Scientific, Fols
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adjusted with the same concentratio
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characterized by the attributes of
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(E,E)-2,4-decadienal (fried/oxidize
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flavor dilution factors, nor did th
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that of the control, but only in th
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e high enough for pyrazine formatio
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sensory panelists analyzing process
Page 179 and 180:
References (ASTM) American Society
Page 181 and 182:
Megahed MG. 2001. Microwave roastin
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Vercellotti JR, Mills OE, Bett KL,
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Table 2- Model system concentration
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28 4-acetoxy-2,5-dimethyl- 3(2H)-fu
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Table 5 - Quantification, sensory o
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Conclusions This research investiga
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microwave technology may provide ma
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protect against colon, prostate, an
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APPENDICES 185
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SAFE (3 SAFE's can be done in 1 day
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2. Turn off waterbath. 3. Turn off
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5. Filter through a third sodium su
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contamination, and run a blank on t
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AC nutty/burnt 975 1.5 NB cabbage/g
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AC oxidized 1289 1.5 NB dusty/nutty
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NB brothy 1612 3.5 NB honey/hay 161
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Table 2: Aroma-Active Compounds in
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AC cedar 1081 3.0 AC burnt sugar/nu
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AC brothy 1350 2.0 NB garlic 1352 5
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NB fruity/floral 1670 3.0 NB rosy 1
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