64
Culinary Quality Evaluations of Potato Selections
K.A. Rykbost and J. Maxwell'
INTRODUCTION
The evaluation of fry color has been a routine part of the potato
variety selection program at most northwest locations where seedling
screening is conducted. Evaluation of culinary quality for various
home preparation cooking methods has not been conducted in the Oregon
program in the past. As the Klamath Basin is the major fresh market
production area in the northwest, KES is the logical location for fresh
market quality evaluations of material in the statewide program. To
assume this role a seldom used building at KES was completely remodelled
in 1989 and equipped to accommodate a culinary quality evaluation
program.
The development of standardized quality evaluation techniques
capable of distinguishing subtle differences in flavor and texture is
beyond the scope of the KES program; however, identification of obvious
quality weaknesses in early generations of the seedling screening program is an attainable and worthwhile objective. Elimination of selections with objectionable flavor, after-cooking darkening tendencies or
serious sloughing problems at an early stage would save the time, effort
and expense of further testing of undesirable selections.
Potatoes were evaluated in boiling, oven-baking and microwavebaking tests. Entries that were retained for further evaluation from
the 1989 Preliminary Yield trial and Oregon Statewide trial were tested.
All entries from the 1989 Advanced Red Variety trial and the Western
Regional trial were also evaluated. Development of testing and evaluation procedures were based on consultations with several individuals
experienced in the field, published information and trial runs using
standard varieties. Further refinements in cooking procedures and
quality assessments will be an important goal for the future.
1/ Superintendent/Associate Professor, Biological Sciences Research
Technician, respectively, Klamath Experiment Station
65
PROCEDURES
A four-burner, 30-inch, Hotpoint-Model RB356J, electric range was
used for boiling and oven-baking tests. Boiling tests were conducted in
6-quart, porcelain-coated steel cookware with lids. Tubers were peeled
immediately prior to boiling with Daisy Stripper electric peelers. An
Amara Radarange - Model RS 415T, 700-watt microwave was used for
microwave-baking.
Tubers tested were stored at approximately 40° F in the KES potato
storage from harvest until testing was done in March. For boiling
tests, 6-ounce tubers were washed, peeled and boiled whole. Four tubers
of a single selection were cooked in one pot, with four pots used
simultaneously. Tubers were placed in 3 quarts of cold water, brought
to a boil and boiled for 30 minutes.
Oven-baking samples were 8- to 10-ounce tubers which were washed and
punctured just prior to cooking. Four tubers of four selections were
baked simultaneously on baking sheets for one hour at 400 ° F. After 30
minutes, samples were rotated from top to bottom shelves, or vice-versa,
to achieve even heating.
Four 8- to 10-ounce tubers of each of two selections were baked simultaneously in the microwave. Tubers were punctured prior to cooking,
rotated from top to bottom shelf and turned over at ten minutes, and
cooked at full power for a total of 20 minutes.
All quality ratings were done by one individual with a rating for
each parameter assigned to each tuber in the test. In boiling tests,
tubers were rated for sloughing, after-cooking darkening, flavor and
texture. Sloughing ratings were as follows: 1) deep sloughing through
the vascular ring; 2) some sloughing of the surface not deeper than the
vascular ring; 3) minor bubbling at the surface of at least three
tubers; 4) none. After cooking darkening was rated 30 minutes after
completion of cooking. The rating scale ranged from 1 (severe darkening) to 4 (no discoloration). Flavor and texture ratings were from 1
(poor) to 4 (excellent), and were scored within 5 minutes of the completion of cooking. In baking tests, after-cooking darkening, flavor
and texture were recorded using the same rating system. Comments were
recorded when unusual characteristics were identified.
The tests were conducted by method in sequence. All boiling tests
were completed first, oven-baking tests second and microwave baking
last. Entries, including standards, were unknown by the evaluator.
Russet Burbank, Lemhi and Norgold were standards in three of four
experiments and Norkotah and Red LaSoda in two trials.
66
RESULTS AND DISCUSSION
Potato varieties and selections vary in the time required for complete cooking. Differences were observed in these tests and accounted
for in a simple penetration test. In more detailed quality evaluations
adjustments in cooking times would be necessary. For the purposes of
selection screening the additional effort is probably not justified.
Data on the degree of doneness are not included in this report. However, in some cases over or under cooking of samples account in part for
excessive sloughing and poor texture ratings.
Sloughing of tuber flesh from peeled potatoes during boiling was
observed in a number of entries in each of the trials (Tables 1, 2, 3
and 4). The extent of sloughing was undoubtedly increased by cooking
whole tubers for a longer time. Frequently in home cooking tubers are
quartered to reduce cooking time. The choice to cook tubers whole was
made partly to increase the opportunity to detect this weakness. Severe
sloughing (1.0) was observed in 6 entries of 82 tested, with an additional 22 entries rated between 1.0 and 2.0. In view of the extent of
sloughing observed, the boiling procedure may need to be altered slightly in the future.
Very few entries exhibited after-cooking darkening. This was
observed more frequently in the boiling test than in either baking
method. Entries A085257-2 in the Preliminary Yield Trial, A084134-1
in the Statewide Trial, and Red Pontiac and Dark Red Norland-strain 13
were the only selections to show consistent darkening tendencies.
Poor texture was also most frequently noted in boiled samples.
Pasty or soggy consistency was considered poor or fair. Severe
sloughing was often coincident with a poor texture rating. Texture
ratings between baking methods were somewhat inconsistent. In microwave baking 8 of 82 entries were rated 2.0 or less. Twelve entries
rated 2.0 or less in oven-baking. Only two of these, Redsen and Dark
Red Norland, were in both groups. Dark Red Norland was the only
selection that received a rating of 2.0 or less in all three cooking
methods.
Agreement between cooking methods was best in the flavor ratings.
In the Preliminary Yield trial flavor problems were noted in A085010-1
and A085165-1. C008014-1 was rated at 2.0 in each cooking method in the
Statewide trial. Western regional entries AC7869-17 and C07918-11
exhibited poor flavor in all three tests. Red Cloud rated poor baked by
either method but good boiled.
Total scores were calculated by adding scores in each parameter and
cooking method. Higher total scores correspond to better overall
quality. Seven entries achieved total scores below 30.0. Each of these
were quite deficient in at least one quality area. Serious flavor
problems were noted in three entries with total scores above 30.0
67
Ratings for Russet Burbank were consistently high. Lemhi ratings
ranged from a high of 37.8 to a low of 30.0 in the total score. Serious
sloughing and poor texture and flavor of boiled tubers in the Statewide
trial accounted for the discrepancy. Norgold was quite consistent in
ratings in two of three experiments but was downgraded for sloughing and
texture in the Western Regional trial. Red LaSoda and Norkotah were
quite similar in ratings between trials except in sloughing.
SUMMARY AND CONCLUSIONS
The results of culinary quality evaluations must be considered very
preliminary. Further refinements in cooking procedures and ratings will
be required to improve consistency; however, quality limitations of
several selections were apparent. Bitter flavor was noted in most
entries that were consistently downgraded for flavor. If these results
are substantiated in two years those selections should be discarded.
Two entries in the Western Regional trial; AC7869-17 and C07918-11,
had poor flavor ratings in all cooking methods. These selections will
be included in the 1990 trials and will be checked again for culinary
quality. If the problem occurs again this will clearly demonstrate the
need for culinary quality tests at an earlier stage in the selection
process.
Testing of 1990 crops will be completed at an earlier date. All
entries in the Oregon Statewide program will be evaluated. Additional
testing of questionable selections may be necessary to confirm serious
quality limitations.
Equipment for french fry quality testing is being installed in the
KES potato quality laboratory and will be available for use on 1990
crops. Cooperative programs with the UC Tulelake Field Station are
anticipated to utilize this capability in the future.
68
Table 1. Culinary Quality ratings of selections in the 1989 Preliminary Yield Trial
Entry
No. Selection
1
2
3
4
Slough
Darkening
Oven Micro
Boil bake bake
Texture
Oven Micro
Boil bake bake
Flavor
Oven Micro
Boil bake bake
Total
score
R. Burbank
Lemhi
Norgold R.
R. Norkotah
2.8
2.8
3.3
4.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
3.0
4.0
4.0
3.5
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
2.0
4.0
4.0
4.0
2.0
3.0
3.0
3.0
3.0
4.0
3.0
4.0
3.0
4.0
35.8
37.8
32.8
37.0
5
6
7
10
A084515-2
A085004-3
A085010-1
A085010-10
2.8
1.5
2.0
1.5
4.0
3.5
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
3.0
1.0
3.0
4.0
4.0
3.0
3.0
4.0
3.0
1.0
3.0
37.8
34.0
31.0
33.5
19
21
27
34
A085027-1
A085031-7
A085066-2
A085116-1
1.4
4.0
2.8
1.0
3.5
4.0
3.3
2.8
4.0
4.0
3.0
3.0
4.0
3.5
4.0
4.0
3.0
4.0
2.0
4.0
4.0
2.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
3.0
3.0
4.0
3.0
4.0
3.0
4.0
4.0
4.0
32.9
37.5
34.1
33.8
38
39
40
44
A085164-2
A085165-1
A085165-2
A085205-2
1.3
3.5
1.3
2.8
4.0
4.0
3.3
3.0
4.0
3.0
4.0
4.0
4.0
3.5
4.0
3.0
2.0
2.0
2.0
4.0
4.0
2.0
4.0
4.0
4.0
4.0
3.0
1.0
4.0
2.0
3.0
3.0
3.0
2.0
4.0
3.0
4.0
3.0
4.0
4.0
34.3
29.0
32.6
31.8
47
54
56
65
A085224-1
A085257-2
A085257-4
00085225-4
1.3
4.0
2.8
3.8
4.0
3.8
4.0
4.0
4.0
2.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
2.0
3.0
4.0
3.0
4.0
3.0
3.0
3.0
4.0
3.0
3.0
3.0
4.0
3.0
4.0
4.0
4.0
3.0
4.0
3.0
4.0
3.0
4.0
33.3
34.8
32.8
37.8
Table 2. Culinary Quality ratings of selections in the 1989 Statewide Trial
Entry
No. Selection
1
2
3
4
Slough
Darkening
Oven Micro
Boil bake bake
Texture
Oven Micro
Boil bake bake
Flavor
Oven Micro
Boil bake bake
Total
score
R. Burbank
Lemhi
Norgold R.
R. Norkotah
3.3
1.0
3.0
2.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
3.0
4.0
1.0
1.0
3.0
3.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
2.0
3.0
3.0
4.0
3.0
3.0
4.0
4.0
3.0
3.0
4.0
38.3
30.0
33.0
33.0
5
6
7
9
10
A74212-1E
A74212-1L
0008014-1
A082283-1
A082611-7
1.5
4.0
1.8
1.0
2.3
4.0
4.0
4.0
3.5
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.5
4.0
4.0
3.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
2.0
3.0
4.0
4.0
4.0
2.0
2.0
3.0
4.0
3.0
2.0
3.0
4.0
3.0
3.0
2.0
3.0
4.0
35.5
38.0
28.3
31.5
37.3
12
14
15
18
20
A081362-3
00083021-10
A083037-10
A083177-6
A082281-1
1.0
3.3
1.3
1.5
4.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
1.0
4.0
3.0
3.0
4.0
2.0
4.0
2.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
3.0
3.0
3.0
4.0
4.0
4.0
3.0
1.0
4.0
3.0
3.0
4.0
4.0
4.0
4.0
30.0
37.3
29.3
36.5
37.0
24
25
27
34
35
A083196-15
A082260-4D
ND02845-1
ND03057-2
00084206-2
1.8
3.8
4.0
2.5
4.0
4.0
3.8
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4.0
2.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
34.8
38.6
40.0
36.5
40.0
37
39
41
48
A084050-2
A084134-1
A084172-6
00084055-205
2.0
4.0
2.5
2.8
3.0
1.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
3.5
4.0
4.0
4.0
4.0
2.0
4.0
4.0
2.0
2.0
4.0
3.0
4.0
3.0
4.0
4.0
3.0
4.0
3.0
3.0
2.0
4.0
4.0
4.0
3.0
4.0
3.0
35.0
29.5
33.5
36.8
69
Table 3. Culinary Q”ality ratings of selections in the 1989 Western Regional Trial
Darkening
Oven Micro
Boil bake bake
Texture
Oven Micro
Boil bake bake
Flavor
Oven Micro
Boil bake bake
Total
score
Selection
Slough
R. Burbank
Lehi
Norgold R.
Red Lasoda
Shepody
3.8
2.3
1.5
2.8
3.0
4.0
4.0
4.0
4.0
4.0
3.5
4.0
4.0
3.5
4.0
4.0
4.0
4.0
4.0
4.0
3.0
3.5
2.0
4.0
4.0
4.0
2.0
4.0
2.0
4.0
4.0
4.0
2.0
3.0
3.0
4.0
3.5
2.0
4.0
4.0
4.0
4.0
2.0
3.0
3.0
3.0
4.0
3.0
4.0
4.0
37.3
35.3
28.5
34.3
37.0
Cal Gold
Cal-Ore
Minnesota R.
Frontier R.
4.0
3.7
3.8
1.3
4.0
4.0
4.0
3.8
3.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
3.0
3.0
2.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.5
3.0
3.0
4.0
2.0
1.0
4.0
4.0
4.0
3.0
4.0
37.0
34.2
33.8
35.1
A7816-14
A7961-1
AC77101-1
AC7869-17
AC81198-11
1.8
3.5
3.0
2.0
2.3
4.0
4.0
4.0
4.0
3.5
4.0
4.0
4.0
4.0
4.0
3.5
4.0
4.0
4.0
4.0
3.0
4.0
4.0
3.0
3.0
2.0
3.0
4.0
4.0
4.0
3.0
4.0
3.0
4.0
4.0
3.0
3.0
4.0
1.0
4.0
4.0
4.0
4.0
1.0
4.0
4.0
4.0
4.0
1.0
3.0
32.3
37.5
38.0
28.0
35.8
A081216-1
A082283-1
A082611-7
B00038-1
C07918-11
3.0
1.0
2.0
4.0
4.0
3.0
3.5
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4.0
3.0
3.0
3.0
2.0
4.0
3.0
3.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
2.0
3.0
3.0
4.0
4.0
1.0
4.0
4.0
3.0
4.0
1.0
35.0
32.5
36.0
37.0
32.0
C008011-5
NDTX8-731-1R
NDTX9-1068-11R
TND329-1RUS
2.3
4.0
3.8
1.5
4.0
4.0
4.0
3.8
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
2.5
4.0
4.0
3.5
4.0
4.0
4.0
4.0
4.0
3.0
2.0
4.0
4.0
4.0
3.0
3.0
3.0
4.0
4.0
3.0
4.0
4.0
3.0
3.0
35.8
39.0
35.8
33.8
AD7267-3
AD7818-5
NDD837-2
A7411-2
4.0
1.0
2.5
3.8
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
2.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
3.0
4,0
3.0
3.0
4.0
4.0
1.0
4.0
3.0
4.0
3.0
4.0
37.0
34.0
33.5
38.8
Table 4. Culinary Quality ratings of selections in the 1989 Advanced Red Variety Trial
Selection
Slough
Darkening
Oven Micro
Boil bake bake
Texture
Oven Micro
Boil bake bake
Flavor
Oven Micro
Boil bake bake
Total
score
Red LaSoda
Sangre
Red Pontiac
Chieftain
1.5
4.0
3.5
2.0
3.0
4.0
1.5
3.5
4.0
4,0
4.0
4.0
4.0
4.0
2.5
4.0
3.0
4.0
4.0
3.0
3.0
3.0
3.0
4.0
4.0
2.0
3.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
34.5
37.0
32.5
36.5
Viking
Bison
Red Norland
Dark Red Norland
3.0
4.0
2.5
3.0
3.8
2.5
4.0
3.3
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
2.0
4.0
4.0
2.0
4.0
3.0
3.0
2.0
4.0
4.0
4.0
2.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
3.0
3.0
4.0
3.0
35.8
36.5
36.5
30.3
D.R. Norland-13
Red Cloud
Redsen
A82705-1
4.0
2.8
2.3
4.0
1.3
3.5
3.3
4.0
3.5
4.0
4.0
4.0
2.3
4.0
3.3
4.0
2.0
3.0
3.0
4.0
3.0
4.0
2.0
4.0
3.0
4.0
2.0
4.0
2.0
3.0
3.0
4.0
4.0
1.0
3.5
4.0
3.0
1.0
3.5
3.0
28.1
30.3
29.9
39.0