Data to be collected for fruit quality evaluation purposes was discussed last
year at our annual meeting in Michigan and reported in the minutes. I have recently
had a number of questions regarding fruit quality evaluation and the protocol
for our project. With the help of the Fruit Quality committee, I have put together
a more detailed protocol and list of mandatory and optional data to collect.
I hope this clarifies any questions you may have and puts all our participants
on a "level playing field". In the early stages and particularly for
those who may not have had any experience with a particular cultivar, judging
when to harvest will be difficult. Our aim is to harvest the quality evaluation
sample for data reporting at a starch index rating of 4 to 6. Use the method
you are most comfortable with, given your resources, to bracket that SI period.
We have purposely omitted any data on sensory evaluation because of the difficulty
of standardizing this area. Hopefully those who wish to provide sensory data
and are familiar with procedures will share their ideas with the group at the
next annual meeting. All the procedures suggested here are subject to revision
at a later date upon concurrence of project members. Please feel free to contact
me if additional information is needed (304-725-3451,ext.326; smiller@asrr.arsusda.gov).
NE-183 Fruit Quality Evaluation Protocol - 1997
Treat each individual tree as a single replication and harvest and collect
quality data from each tree. Attempt to harvest the data sample at a starch
index rating of 4 to 6. If tree has less than 10 fruits, indicate number
of fruits in the quality sample. Report the date the sample was harvested
(MMDDYY). Report data as described in the memo dated November 6, 1995, "NE-183
Regional Project Data Collection". Use columns to report data for individual
fruits, e.g. fruit weight would have 10 data columns each representing a
single fruit's weight. Starch Index rating would have one data column representing
the mean for the 10 fruit sample.
Select at random a 10 fruit sample from each tree for quality evaluation
and collect the following data:
1. Fruit weight. Report the individual weight of each of the 10
fruits to the nearest gram.
2. Fruit length and diamater. Report the total length and total
diameter of the 10 fruit sample to the nearest millimeter. This can be easily
done using a wooden trough with a meter stick attached in the bottom of
the trough.
3. Soluble solids concentration (SSC). Determine the SSC and
report in % to one decimal from a composite juice sample collected from
all 10 fruit.
4. Starch index rating. Assign a starch index rating to each
individual fruit and compute the mean SI for the 10 apple sample. Report
the mean SI index rating. Use the procedure and the 1 to 9 rating scale
described in Cornell Information Bulletin 221. Report SI rating (mean of
the 10 fruit) to one decimal.
Any one or all of the following data can be taken as optional:
1. Flesh firmness. Record the mean flesh firmness from two
readings per fruit using a McCormick (Effigi) penetrometer. Use the standard
11.1 mm penetrometer tip. Read to the nearest 0.25 pounds. Report the mean
firmness (mean of the 10 fruit) for the sample as pounds firmness to the
nearest one decimal.
2. Titratable acidity (TA). Determine TA on the composite juice
sample. Add a 1 ml aliquot of juice to distilled water and bring volume
to 100 ml. Titrate to an end point of pH 8.1 using 0.01 N NaOH. Report volume
of titer in milliliters to one decimal to titrate to pH 8.1 for the sample.
3. Color space readings. Record the L*a*b* values from four
quadrants of the fruit at the equator. Compute the mean L*a*b* value and
report for each fruit. Report values to one decimal.
4. Fruit overcolor (red). Estimate to the nearest 5% the percent
surface showing typical red overcolor for the cultivar. Report the mean
for the 10 apple sample.
5. Fruit russet. Estimate the severity of russet on a scale of 0
= none to 5 = severe (20.1% or more of fruit surface with russet). Use the
following scale: 0 = none, 1) = 0.1% to 5%, 2) = 5.1% to 10%, 3) = 10.1%
to 15%, 4) = 15.1% to 20%, and 5) = 20.1% or more. Report the mean russet
rating for the sample.