quality assessment of high and normal oleic acid peanut

Quality Assessment of Various Peanut Butters 1

Quality Assessment of High and Normal Oleic Acid Peanut Butters by Sensory and

Volatile Flavor Compound Analysis

Stephen Koltun

Advisor: Paul J. Sarnoski

University of Florida

Institute of Food and Agricultural Sciences

Department of Food Science and Human Nutrition

Gainesville, Florida, 32611


Abstract

Two peanut genotypes (Florunner and Tufrunner) were analyzed using gas

chromatography-mass spectrometry (GC-MS) to determine variations in lipid oxidation,

as well as the pyrazine compounds that correlate highly with roasted flavor and aroma.

Compounds were measured using headspace solid-phase microextraction (SPME) after

peanuts were roasted and made into three peanut butters (normal oleic, high oleic

without skin, high oleic with skin) according to the Standard of Identity for peanut butter.

Peanut butters were stored at 40 ˚C for accelerated shelf life testing (ASLT) and three

sensory panels were conducted at various times (initial, 56 days, 98 days) in order to

assess 8 characteristics (oxidized aroma, sweetness, bitterness, saltiness, brown color,

texture, flavor, overall acceptability). Results showed that high oleic varieties had a

slower rate of lipid oxidation when compared to the normal oleic variety. Sensory panel

results indicated that high oleic with skin peanut butter was the most favored of the

three experimental varieties and was comparable to commercial brand peanut butters.

The inclusion of peanut skins is also known to have health benefits due to their

concentration of phenolics and dietary fiber.

Keywords: gas chromatography-mass spectrometry (GC-MS), lipid oxidation, solid-

phase microextraction (SPME), peanut butter, oleic acid, accelerated shelf life testing

(ASLT)


Introduction

Peanuts (Arachis hypogaea) are a popular legume that originated in South

America. They are grown around the world, with the United States being the fourth

largest producer (USDA-FAS 2016). Peanuts are sensitive to soil and climate

conditions, so they are mainly grown in three major areas: the Southeast (Alabama,

Florida, Georgia, Mississippi, South Carolina), the Southwest (New Mexico, Oklahoma,

Texas), and Virginia and North Carolina, with Georgia being the largest peanut-

producing state (USDA-NASS 2016).

In the United States, production of peanuts is estimated to be at 6.21 billion

pounds (USDA-NASS 2016). There are four major cultivar groups that are the most

popular in the United States: Runner, Spanish, Valencia, and Virginia. Runner peanuts

are most commonly used in peanut butter and salted nuts due to good flavor, better

roasting characteristics, and higher yield compared to Spanish types.

Peanut butter processing consists of several steps: cleaning, shelling, roasting,

cooling, blanching, grinding, and packaging. After cleaning and shelling, peanuts are dry

roasted using either the batch or continuous method. The batch method is more

common, which involves heating batches of peanuts to 160 ˚C for 40 to 60 min. A

photometer is used to indicate when desired doneness is achieved, as well as ensure a

uniform product has been produced. The peanuts are transferred to a perforated metal

cylinder where they are cooled using a large volume of air. At this point a manufacturer

can decide to remove the skins by either heat or water blanching. Heat blanching is

more common and it uses heat, agitation, and gentle rubbing to separate the skins from

the peanuts. The product goes through an inspection process that removes any


unwanted particles, including but not limited to: scorched or rotten peanuts, light

peanuts, discolored peanuts, and foreign contaminants like metal. The peanut butter is

made by two grinding operations. The peanuts are first reduced to a rough, medium

grind and then to a fine, smooth texture. At this point, additives like salt, sugar, and

stabilizers are fed into the peanut butter to add flavor, improve consistency, and

lengthen shelf life. The stabilized peanut butter is finally vacuum packaged or flushed

with inert gas in order to reduce oxidation (Considine 1982).

Of all the processing steps, the only critical control point that can kill potential

microorganisms is roasting. That means that the peanut butter is susceptible to

pathogenic bacteria, mainly Salmonella spp., in all subsequent unit operations.

Salmonella tennessee, Salmonella typhimurium, and Salmonella bredeney outbreaks

have occurred in peanut butter in 2007, 2008, and 2012 respectively (Sheth et al. 2011;

CDC 2009, CDC 2012). In response to these various outbreaks, research has been

conducted in order to eliminate the bacteria in the final product without affecting the

overall quality.

There has been a shift in consumer demand towards natural foods with fewer

preservatives and additives, but partially hydrogenated oils (PHOs) have been used in

the peanut butter industry to improve consistency in peanut butter products. The U.S.

Food and Drug Administration (FDA) has issued a recent ordinance that states PHOs

are no longer recognized as GRAS, or generally recognized as safe, for human

consumption (2015). This research focuses on high oleic peanuts that will be made into

a shelf stable peanut butter. The peanut butter that does not use any PHOs may be

used as a viable alternative to combat the ever-changing food laws.


Lipid Oxidation in Peanuts and Peanut Products

Oxidative rancidity is the result of chemical reactions involving oxygen and a

lipid. Lipid oxidation is referred to as autoxidation because it is an autocatalytic reaction,

which the reaction rate increases as the reaction proceeds. It results in off flavors, color

change, degradation of nutrients, and possibly toxicity. The rate of oxidation is affected

by fatty acid composition, degree of unsaturation, presence of pro- and antioxidants,

partial pressure O2, storage conditions, water activity, and pH (Choe and Min 2006).

There are three steps of autoxidation: initiation, propagation, and termination.

During initiation, a hydrogen atom is abstracted from the fatty acid by an initiator and a

fatty acid free radical is formed. In propagation, a peroxyl free radical is formed in the

presence of oxygen which leads to the formation of a hydroperoxide in the presence of

another fatty acid. This reaction repeats rapidly. Termination happens with the reaction

between two radicals (Frankel 2005). Hydroperoxides (primary products) can be very

unstable and decompose to form secondary oxidation products, which include: acids,

alcohols, aldehydes, carbonyls, and ketones. These secondary products are

responsible for the rancid odor and flavor of oxidized fat.

There are various methods to prevent and/or retard lipid oxidation, the most

obvious being the removal of oxygen by using vacuum or modified atmosphere

packaging. Removing or decreasing oxygen in the system means the lipid molecules

cannot be oxidatively deteriorated. Other important methods are avoiding high

temperatures, using less unsaturated fatty acids or using more saturated fatty acids,

and incorporating the use of antioxidants. Autoxidation can also be retarded by reducing

light and by removing catalysts (e.g. metals).


High-Oleic Peanuts

Peanuts mainly consist of oleic and linoleic acid. Oleic acid is a monounsaturated

fatty acid with one double bond (C18:1), while linoleic acid is a polyunsaturated fatty

acid with two double bonds (C18:2) (Caballero 2016). Peanuts usually contain about

52% oleic acid, but there are peanuts known as high oleic peanuts that contain about

80% oleic acid (Derbyshire 2014). The fatty acid composition of high and normal oleic

acid peanuts is otherwise relatively similar, except for differences in palmitic acid

(C16:0) and linoleic acid (C18:2) (Braddock 1994). High oleic peanuts also have a lower

sugar content and increased thermal stability when compared to normal oleic peanuts

(Chung et al. 2002; Derbyshire 2014). Due to an increased thermal stability, high oleic

peanuts produce less undesirable flavor characteristics such as painty, cardboard, and

oxidized (Nepote et al. 2008).

The high oleic trait is genetically controlled by two recessive genes: AhFAD2A

and AhFAD2B. The AhFAD2A gene is more common in Runner and Virginia peanuts,

but it is not present in Spanish peanuts. These high oleic peanut cultivars have been

developed with a variety of techniques, including conventional breeding (SunOleic97R,

Tamrun OL01, Georgia04S), chemical mutagenesis (Flavorunner 458), and gamma

irradiation (Georgia-02C) (Benkeblia 2011).

Oleic content is measured using gas chromatography (GC), capillary

electrophoresis, near-infrared reflectance spectroscopy (NIRS), and real-time PCR (RT-

PCR). GC and capillary electrophoresis are able to determine the oleic acid to linoleic

acid (O/L) ratio, the only difference being that GC uses large sample sizes and capillary

electrophoresis uses a smaller sample size. NIRS and RT-PCR are both non-


destructive tests, but these tests are only able to determine whether or not a peanut

sample is high in oleic acid and not the overall O/L ratio (Chamberlin et al. 2014).

Materials and Methods

Sample Preparation and Storage

Two peanut genotypes were analyzed; Florunner, a normal-oleic variety; and

Tufrunner, a high-oleic variety. Peanut yield, shelling, and grading data were obtained

from the University of Florida North Florida Research and Education Center (NFREC) at

Marianna, Florida and sound, mature seed samples (medium and above grade size)

were sent to the University of Florida, Gainesville, for further analysis. Peanut seeds

were stored at -20 ˚C in nitrogen-flushed, sealed plastic Hefty One-Zip Slider© (Lake

Forest, Ill., U.S.A.) freezer bags.

Peanut Roasting

Frozen, unroasted, shelled peanuts were allowed to equilibrate to room

temperature for approximately two hours before roasting. Roaster heating was set to

reach a temperature of 250 ˚C. The Pyrex forced air convection oven (Suppentown

International, City of Industry, CA) was fitted with a thermocouple in the center in order

to ensure that the air temperature was adequate. Each peanut variety was then roasted

in a stainless steel basket in approximately 400 g batches, and stirred three times, for

approximately 8 min for normal-oleic peanuts and 10 min for high-oleic peanuts until

color and odor reached an acceptable roasting level, as determined by Baker et al.

(2003). Peanut batches were removed from the roaster by transferring to a stainless

steel bowl and agitated manually using cotton examination gloves covered by nitrile


gloves to partially remove the skins in a sanitary manner and protect the investigator

from potential burns. Further agitation was required to remove all skins by manually

scraping against a metal sieve (6.5 mm).

Peanuts were transferred to a kitchen blender (Ninja Kitchen System, Newton,

MA) where salt, sugar, and peanut skins were added depending on the batch. In order

to keep with the Standard of Identity for Peanut Butter (U.S. CFR 21), 1.6 g of salt and

10.4 g of sugar were added per 100 g of peanuts. For the high oleic peanuts with skins,

6.82 g of peanut skins were added per 100 g of peanuts. The mixture was then

homogenized for approximately 15 min or until there were no noticeable granules of

significant size.

The homogenized peanut paste was then transferred to an induction-heated

kitchen mixer (Kenwood, Upper Saddle River, NJ), fitted with a U-shaped Teflon

attachment to scrape the peanut mixture at 140 ˚C for another 15 min, which should

have been an adequate to pasteurize the product (71.7 ˚C/161 ˚F for 15 sec). The

resulting peanut butter samples were immediately poured into sterile, 4-ounce sample

specimen cups and stored at 45 ˚C for accelerated shelf life testing (ASLT).

Sensory Analysis

A 10-person (4 male, 6 female) sensory panel consisting of students and staff of

the Food Science and Human Nutrition Department were used to evaluate the peanut

butters. Six different peanut butters were tested (three experimental varieties and three

commercial brands): Florunner, unblanched Tufrunner, blanched Tufrunner, unblanched

Trader Joe’s, Skippy Natural, and Peter Pan. Sensory attributes rated were oxidized

aroma, sweetness, bitterness, saltiness, brown color, texture, flavor, and overall


acceptability. Oxidized aroma, sweetness, bitterness, saltiness, and brown color were

rated for intensity on a 150 mm line scale with predetermined anchors for each attribute

(Gills and Resurreccion 1999). The six peanut butters were also ranked for texture,

flavor, and overall acceptability. On the test day, all stored peanut butters were

equilibrated to room temperature and mixed to mimic typical use conditions before

sensory evaluation. Panelists were given approximately 10 g of peanut butter per

sample and told to evaluate all intensity attributes before moving on to ranking the

peanut butters.

Solid-Phase Microextraction (SPME)

Peanut butter samples were transferred to 40-mL vials fitted with

polytetrafluoroethylene (PTFE) septa caps (Fisher Scientific, Pittsburgh, Pa., U.S.A.),

enough to fill half of the vial. Vials were shaken for 1 min and allowed to settle, while

sealed, then heated to 60 ˚C for 15 min. The 50/30 µm

divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fiber (Agilent

Technologies, Santa Clara, Ca., U.S.A.) was then inserted into the vial via the septa,

exposing the fiber to the headspace of the roasted peanut butter sample for 15 min to

obtain headspace/fiber equilibrium (Baker et al. 2003). Samples were then analyzed by

gas chromatography-mass spectrometry (GC-MS) using a 5975 MSD (Agilent

Technologies, Santa Clara, Ca., U.S.A.) and a ZB-WAXplus column with 30 m length,

0.25 mm I.D., and 0.25 µm film thickness (Phenomenex, Torrance, Ca., U.S.A.). Volatile

compounds were separated using temperature programming. Thermal desorption for 3

min in the injection port was required in order to remove all compounds from the fiber.


Statistical Analysis

Statistical Analysis Software (SAS 9.4) was used for statistical analysis of

sensory panel data. Two-way Analysis of Variance (α = 0.05) was used to determine

significant effects of treatment on attribute intensities (Table 1). Duncan’s multiple range

test was performed in order to separate means based on significance for oxidized,

sweetness, bitterness, saltiness, and brown color. Friedman’s analysis (α = 0.05) was

used to determine significant effects of treatment on attribute rankings (Table 2). Least

significant difference (LSD) was performed in order to separate rank totals based on

significance for texture, flavor, and overall acceptability.

Results

Sensory Analysis

There was a total of 8 variables used in the sensory panel to quantify the

characteristics of six different peanut butters (three experimental varieties and three

commercial brands) and they are summarized in Tables 1 and 2. During the initial

sensory test, all six peanut butters had relatively low oxidized values and no significant

differences were found. As time went on, the sensory tests after 56 and 98 days

showed a significantly greater level of oxidation for the normal oleic peanut butter when

compared to the high oleic peanut butters. Three tastes: sweetness, bitterness, and

saltiness were rated by sensory analysis. All three of these attributes were rated lower

for all of the experimental peanut butters as time went on. There was a significant

difference among the peanut butters in terms of brown color. The high oleic with skin

variation was significantly darker in brown color than all other peanut butters. Brown


color was relatively unaffected by time for every peanut butter variety. Panelists were

required to rank the peanut butters against each other for texture, flavor, and overall

acceptability. For each of these attributes, the high oleic with skin variation was

significantly more favorably ranked than the other two experimental peanut butters and

this peanut butter even ranked significantly higher than some of the commercial brands.

Solid-Phase Microextraction (SPME)

Samples were analyzed using GC-MS. Chromatogram peak areas for

compounds of interest were converted to percentages and are summarized in Tables 3,

4, and 5 for normal oleic, high oleic without skin, and high oleic with skin, respectively.

The normal oleic peanut butter showed a greater rate of oxidation when compared to

the high oleic peanut butters due to a drastically higher concentration of oxidation

products. Over the course of the study, the normal oleic variety saw a 1975% increase

in pentanal, 2334% increase in hexanal, and 2277% increase in 1-pentanol. The high

oleic varieties started showing signs of oxidation at the 56 day mark, characterized by

the presence of hexanal.

Pyrazine compounds are responsible for a range of sensory responses. In all

three of the experimental varieties, these compounds are found during the initial

analysis and have a negative correlation with regard to time. Some of these pyrazine

compounds degraded so much that they were not found during the final analyses.

These pyrazine compounds are detected in the high oleic varieties for a longer period of

time when compared to the normal oleic variety. In the normal oleic peanut butter,

compounds such as trimethylpyrazine and 2,5-dimethylpyrazine are no longer found in


the sample at the 56 day mark. However, the high oleic peanut butters retained most of

their pyrazine compounds up until the 98 day mark.

Discussion

Being one of the most important attributes of this study, rancidity in peanuts is

described as the aroma associated with oxidized, stale peanuts. Peanut butter oxidation

showed a clear, positive correlation with regard to time. This is due to the nature of the

study as the accelerated shelf life testing requires the peanut butter be subjected to

harsh environmental conditions like increased storage temperatures, which increases

the rate of oxidation. Sweetness is the taste associated with sucrose solutions,

bitterness is the taste associated with caffeine solutions, and saltiness is the degree of

the taste sensation associated with sodium chloride solutions (Gills and Resurreccion

1999). The decrease in these attributes over time are most likely due to the respective

compounds being lost in the sample as thermal degradation and oil separation

occurred. Brown color was the only visual attribute that was examined over time and it

is the intensity or strength of brown color from light to dark brown. Brown color of the

experimental varieties was comparable to that of the three commercial brands. The high

oleic experimental peanut butters with skins had some negative feedback due to the

added skins, but panelists indicated that it was minor. Panelists were required to rank

the peanut butters against each other instead of on an individual basis to give the

researchers an idea of how the peanut butters would compare if released in the market.

Results indicated that the high oleic with skin variation was the most favorable of the

three experimental varieties and was comparable to the commercial brands.


The other part of the experiment was to use GC-MS to quantify the compounds

in the experimental peanut butters as the samples underwent lipid oxidation over time.

As previously discussed, hydroperoxides (primary products of lipid oxidation) can

undergo further oxidation to form a variety of volatile and nonvolatile secondary

products when exposed to elevated temperatures (Frankel 2005). Compounds of

interest for this study included alkanes, alkenes, alcohols, aldehydes, and pyrazines.

While pyrazines are not a product of oxidation, these compounds are associated with

roasted aromas in peanuts and are prone to degradation over time. A summary of these

sensory responses to pyrazines is given in Table 6 (Braddock 1994).

The compounds in the peanut butters fluctuated in concentration throughout the

study, but most of them show a clear positive or negative trend. Any deviations from this

could be due to the nature of the technique used to measure oxidation. At different

points during oxidation, production of different compounds may be more or less

favorable. This may have been the reason why fluctuations in compound amount were

seen at different points in time. Overall you see that the high oleic experimental varieties

have a longer induction period, which is defined as the length of time before rapid

acceleration of lipid oxidation occurs.

Overall, the GC-MS data agreed with the results from the sensory panel. The

normal oleic peanut butter had higher scores for oxidation throughout the study, which

correlates to the amount of oxidation products that are present in the sample. The

overall decrease in flavor and aroma sensation for the three peanut butters is attributed

to the decrease in pyrazine compounds. Sweetness, roasted, caramel, and nutty are

just a few of the attributes that pyrazine compounds are directly responsible for.


The aim of this study was to determine whether or not a high oleic acid peanut

could be a viable alternative to the normal oleic acid peanut that is currently used for

peanut butter commercially. According to sensory panel data, consumers rated high

oleic with skin peanut butter the highest of all three experimental varieties and it was

ranked equally or higher than some commercial brands. According to GC-MS data, both

of the high oleic peanut butters showed less lipid oxidation than the control. The use of

high oleic peanuts could combat the dangers of microorganisms like Salmonella as

these peanuts can be heated to higher temperatures for longer periods of time without

creating off-flavors as a result of extensive heating. There was little difference between

the two high oleic peanut butters in regard to overall oxidation products, so future

research might benefit from increasing the amount of peanut skin added to each batch.

The nutritional implications of peanut skin also needs to be further researched in order

to be able to market to the health-conscious consumer.

Conclusion

Peanut butter is prone to lipid oxidation because of its unsaturated bonds. High

oleic peanuts are more oxidatively stable compared to normal oleic peanuts due to the

oleic acid to linoleic acid (O/L) ratio. High oleic peanuts can also be heated to higher

temperatures for longer periods of time without negatively affecting the quality of the

peanut butter. Peanut skin has a high polyphenol content, which directly correlates to its

ability to act as an antioxidant and possibly an antimicrobial, as well as other health

promoting compounds. This research demonstrates the ability of high oleic peanut

butter to withstand higher temperature. A peanut butter with high oleic peanuts and


peanut skins is able to be heated enough to potentially destroy microbes, mainly

Salmonella spp., without adverse effects on quality and can also lead to a longer shelf

life without the use of additives.


Literature Cited

Baker GL, Cornell JA, Gorbet DW, O’Keefe SF, Sims CA, & Talcott ST. 2003.

Determination of pyrazine and flavor variations in peanut genotypes during

roasting. Journal of Food Science, 68(1):394-400.

Caballero B. 2016. Encyclopedia of food and health. Oxford: Academic Press, an

imprint of Elsevier.

Braddock, JC. 1994. Stability of volatile flavors and aromas of peanuts with high and

normal oleic acid content. M.S. Thesis, University of Florida.

CDC. 2009, May 11. Multistate outbreak of Salmonella typhimurium infections linked to

peanut butter, 2009-2009 (Final Update). Available from:

http://www.cdc.gov/salmonella/2009/peanut-butter-2008-2009.html. Accessed

2016 November 1.

CDC. 2012, November 30. Multistate outbreak of Salmonella bredeney infections linked

to peanut butter manufactured by Sunland, Inc. (Final Update). Available from:

http://www.cdc.gov/salmonella/bredeney-09-12/. Accessed 2016 November 1.

Chamberlin KD, Barkley NA, Tillman BL, Dillwith JW, Madden R, Payton ME, & Bennett

RS. 2014. A comparison of methods used to determine the oleic/linoleic acid

ratio in cultivated peanut (Arachis hypogaea L.). Agricultural

Sciences, 05(03):227-237.

Choe E, Min DB. 2006. Mechanisms and factors for edible oil oxidation. Comprehensive

Reviews in Food Science and Food Safety, 5(4): 169-186.


Chung S, Maleki S, Champagne ET, Buhr KL, & Gorbet DW. 2002. High-oleic peanuts

are not different from normal peanuts in allergenic properties. Journal of

Agricultural and Food Chemistry, 50(4): 878-882.

Considine DM. 1982. Foods and food production encyclopedia. New York: Van

Nostrand Reinhold.

Derbyshire EJ. 2014. A review of the nutritional composition, organoleptic

characteristics and biological effects of the high-oleic peanut. International

Journal of Food Sciences & Nutrition, 65(7):781-790.

FDA. 2015. FDA cuts trans fat in processed foods. Available from:

http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm372915.htm.

Accessed 2016 June 5.

Frankel EN. 2005. Lipid Oxidation (Second Edition). Woodhead Publishing.

Gills LA, Resurreccion AVA. 1999. Sensory and physical properties of peanut butter

treated with palm oil and hydrogenated vegetable oil to prevent oil separation.

Journal of Food Science, 65(1):173-180.

Sheth AN, Hoekstra M, Patel N, Ewald G, Lord C, Clarke C, . . . Lynch M. 2011, August

1. A national outbreak of Salmonella serotype tennessee infections from

contaminated peanut butter: A new food vehicle for salmonellosis in the United

States. Clinical Infectious Diseases, 53(4):356-362.

USDA-NASS. 2016. Crop production annual summary. Available from:

http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1

047. Accessed 2016 November 1.


USDA-FAS. 2016, June. United States world agricultural service production. Available

from: http://apps.fas.usda.gov/psdonline/circulars/production.pdf. Accessed 2016

November 1.


Tables and Figures

Table 1. Sensory Attribute Intensities of Stored Roasted Peanut Products

Sample

Oxidized Sweetness Bitterness Saltiness Brown Color

0

Day

56

Day

98

Day

0

Day

56

Day

98

Day

0

Day

56

Day

98

Day

0

Day

56

Day

98

Day

0

Day

56

Day

98

Day

Trader Joe’s

Unblanched

25.2

a

25.9

b

26.6

c

20.4

b

17.4

c

20.6

b

25.8

a

41.7

a

34.6

a

49.4

a

41.6

a

32.4

a

79.2

b

85.7

b

76.4

b

High Oleic

w/o Skin

26.3

a

21.2

b

25.1

c

42.9

a

53.4

a

47.7

a

19.7

a

12.3

b

25.4

a

50.1

a

35.3

a

35.9

a

61.8

c

25.9

e

60.7

c

Skippy

Natural

34.2

a

15.2

b

29.9

bc

34.5

ab

32.3

b

44.3

a

19.5

a

20.6

b

20.1

a

44.7

a

41.2

a

32.6

a

70.8

bc

58.4

cd

59.6

c

Normal Oleic 34.0

a

45.8

a

68.4

a

43.5

a

38.7

ab

33.1

ab

15.4

a

24.0

b

32.0

a

46.3

a

36.1

a

50.1

a

30.4

d

44.4

d

30.4

d

Peter Pan 31.2

a

23.6

b

18.6

c

39.9

a

39.3

ab

26.3

b

24.8

a

17.8

b

19.4

a

40.9

a

43.7

a

34.6

a

70.8

bc

69.0

c

63.7

c

High Oleic

w/ Skin

27.3

a

27.0

b

49.9

ab

51.2

a

47.1

ab

32.9

ab

19.1

a

17.8

b

35.4

a

55.4

a

39.4

a

35.0

a

107.2

a

102.3

a

109.3

a

*Intensities based on 0 to 150 scale, mean separation performed with Duncan’s multiple

range test

Table 2. Ranking Sums of Stored Roasted Peanuts from a Sensory Panel

Sample

Texture Flavor Overall

Acceptability

0

Day

56

Day

98

Day

0

Day

56

Day

98

Day

0

Day

56

Day

98

Day

Trader Joe’s

Unblanched

36

ab

29

a

19

bc

20

a

21

a

15

cd

21

d

26

a

16

cd


High Oleic w/o

Skin

32

abc

26

a

20

bc

37

a

28

a

26

abcd

37

abcd

27

a

25

abcd

Skippy Natural 48

a

37

a

35

a

44

a

33

a

31

ab

44

ab

41

a

30

abc

Normal Oleic 17

c

29

a

16

c

32

a

29

a

13

d

22

d

25

a

13

d

Peter Pan 48

a

36

a

33

ab

37

a

37

a

29

abc

47

a

35

a

31

ab

High Oleic w/ Skin 29

bc

32

a

24

abc

40

a

41

a

33

a

39

abc

35

a

32

a

*Rankings based on 0 (lowest possible ranking) to 6 (highest possible ranking) scale,

rank total separation performed with least significant difference (LSD) test

Table 3. Percentage Change of Compounds in Normal Oleic Peanut Butter

Compound 56 Day 98 Day

Pentanal 148% 1975%

Hexanal 722% 2334%

1-Methyl-1H-pyrrole -50% -37%

1-Pentanol 690% 2277%

Methylpyrazine -30% ---

Octanal --- -54%

1-Hexanol -32% -2%

2-Ethyl-6-methylpyrazine -25% -35%


Nonanal -27% -55%

3-Ethyl-2,5-dimethylpyrazine 13% -3%

Benzaldehyde 33% 12%

1-Octanol 63% ---

*Percent changes are all relative to the first time compound was found in sample (i.e.

0%). A “---“ indicates compound was not found in the sample

Table 4. Percentage Change of Compounds in High Oleic Peanut Butter without Skins

Compound 14 Day 28 Day 56 Day 70 Day 98 Day

2-Methyl-2-propanol 0% 3% 72% 8% ---

2-Methylbutanal 9% 47% --- 62% ---

3-Methylbutanal -18% 20% 3% 68% -84%

Hexanal --- --- 0% -73% -13%

1-Methyl-1H-pyrrole -33% -45% -60% -21% -5%

Methylpyrazine --- --- --- -62% ---

2,5-Dimethylpyrazine -69% -57% -93% -57% ---

2-Ethyl-5-methylpyrazine --- -45% --- -46% ---

Nonanal 34% -11% -18% -19% -46%

Trimethylpyrazine -50% -42% --- -38% -78%

3-Ethyl-2,5-dimethylpyrazine -48% --- --- -45% -45%

Benzaldehyde 24% 18% 10% 104% 206%

* Percent changes are all relative to the first time compound was found in sample (i.e.



Table 5. Percentage Change of Compounds in High Oleic Peanut Butter with Skin

Compound 14 Day 28 Day 56 Day 70 Day 98 Day

2-Methylbutanal -24% -39% -34% -1% ---

3-Methylbutanal -30% -49% -36% -9% ---

Hexanal --- --- 0% 24% -22%

1-Methyl-1H-pyrrole -39% -34% -58% -9% -68%

Methylpyrazine --- --- -67% 29% ---

2,5-Dimethylpyrazine -67% -2% -58% 21% ---

2-Ethyl-5-methylpyrazine --- 31% -39% --- ---

Nonanal 151% 208% --- 304% -76%

Trimethylpyrazine -37% 57% -22% 122% -70%

3-Ethyl-2,5-dimethylpyrazine -25% 67% -24% 140% -37%

Benzaldehyde -21% 98% 72% 150% 33%

* Percent changes are all relative to the first time compound was found in sample (i.e.


Table 6. Volatile Compounds Identified in Roasted High and Normal Oleic Acid Peanuts

Compound Sensory Response

Acetic acid bread dough, yeasty

Methylpyrazine grilled chicken, savory

2,5-Dimethylpyrazine malty, chocolate

Ethylpyrazine toasted, dark roasted


2,3-Dimethylpyrazine roasted

Benzaldehyde ---

2-Ethyl-5-methylpyrazine nutty, roasted

2-Ethyl-3-methylpyrazine roasted

Benzeneacetaldehyde floral, sweet, caramel

3-Ethyl-2,5-dimethylpyrazine roasted, slightly sweet

2,3-Dihydrobenzofuran rubbery, harsh

Benzothiazole harsh, rubbery, burnt

3-Methylpyridine intense, peanut butter, roasted

*Adapted from Braddock (1994)

quality assessment of high and normal oleic acid peanut

Documents