Mango Dry Matter Measurement Protocol

Full text

1
Mango Dry Matter Measurement Protocol
Aman U. Malik, Gayle M. Crisosto, Luis Felipe Pérez Romero, Carlos H. Crisosto
chcrisosto@ucdavis.edu
Department of Plant Sciences, University of California, USA
Dry Matter (DM) content is considered an important criterion of mango fruit maturity and/or
consumer quality. DM increases as fruit approaches maturity, and may vary with cultivars.
Therefore, cultivar specific percentage dry matter needs to be determined to precisely estimate
fruit maturity and potential consumer acceptability. This brochure provides methodology for
determining dry matter content for which you will need the following materials:
#
Items
Picture
Model/comments
1
Food Dehydrator
Nesco/American Harvest Snackmaster®
Encore Food Dehydrator Model FD-61 or
similar
http://www.nesco.com/products/Deh
ydrators/Dehydrators/
2
Electronic Top
Loading Balance
Capacity of 200g
Readability of 0.01g
3
Multi Slicer
Prepworks multi slicer or similar
http://progressiveintl.com/products/
multi-slicer
4
Six-inch Chef’s
Knife
Any brand, needs to be sharp
5
Cutting Board
Any brand, nonslip

2
6
Thermometer
0-110°C (32°F-230°F)
Preferably non-glass
7
Weighing Paper
http://www.fishersci.com/categories
09-898-12A
3x3 inches
8
Notebook or
Data sheet
(Appendix-I)
Before you start:
1.
Be sure that the electronic balance is completely leveled and the dehydration process is
done in a secure clean area.
2.
Label the food dehydrator trays. Each tray can be labeled, from A (Top) to D (Bottom),
and from 1-12 (clockwise) within the each tray (Fig. 1-left). Thus, four trays with 12
samples each can accommodate 48 possible samples respectively.
3.
Set dehydrator at 130°F (54°C). Turn it on to warm up. Check the temperature a few
times with a standard probe thermometer (Fig. 1-Right); adjust settings (if needed) to
achieve the desired temperature.
4.
Make sure you choose the thin slicer blade for preparing mango slices. Often it is
written on the side as shown in picture
Fig.1: Left: Labeled food dehydrator tray; Right: Checking temperature with a probe
thermometer.

3
Procedure
a.
Select a representative sample of mango fruits (defect free) like the ones you intend
to harvest, from different trees. Label fruit with proper ID (block, cultivar, harvest
date, etc.) and record on your data sheet or note book.
b.
Mango slices preparation (Fig. 2). For each fruit, record the sample ID (description)
in column-1 on your data sheet (Appendix-I). Cut one slab parallel (Fig.2-1&2) to the
seed and then cut the slab in half longitudinally (Fig.2-3). Turn the half cut slab such
that the cut side is placed flat on the slicer with the stem end oriented towards the
blade (Fig.2-4&5). Slice off (thin slice plate) a ~5mm thick slice (Fig.2-6).
Fig. 2 Stepwise procedure showing preparation of mango slices.
1.
2.
3.
4.
5.
6.

4
c.
Take a piece of weighing paper and write tray position on one corner, weight it, record its
weight in column 5 (paper weight). Now gently place the fresh mango sample slice on the
weighing paper and weigh them together (paper+ slice), initial weight in grams, to the
nearest
hundredths (two decimal places) and record it on the data sheet in column
6.
Now take a dehydrator tray,
record it’s ID in column 3. Place
slices along with paper in the
tray in their respective positions
e.g. 7 and 8, as shown in picture.
Before starting to weigh a new slice, make sure that the electronic balance is at
zero or tare it again prior to weighing the paper.
d.
When all of the sample slices have been placed in the
tray, place it in the dehydrator set
at 130°F (54°C) cover and leave to dry for
approximately 24 hours. Complete column
2 (date and time).
e.
After 24 hours, weigh each slice along with paper as shown in picture, and record its
weight (paper +slice) under “Dry Slice Weight-1” column 7. The samples should be
measured one tray at a time keeping the others in the dehydrator to prevent the
slices from reabsorbing moisture.
f.
After weighing, place the slices back in the same positions in the dehydrator.
g.
Run the dehydrator for another hour or two with the mango slices and then reweigh, record the
weights under “Dry Slice Weight-2” in column 8. Compare the two Dry Slice Weight
measurements (column 7 and 8). If the weight has not changed for each sample more
than one hundredth of a gram (.01), the dehydration process has ended, and that
weight (column 8) is taken as the final reading (final dry weight). Be sure that
burning does not occur anytime during the dehydration process.
h.
Calculate net fresh slice weight by subtracting the paper weight (column 5) from the
initial slice weight (column 6) and record it in column 9.
i.
Now calculate net final dry weight of slices by subtracting paper weight (column 5)
from final dry weight (column 8) and record it in column 10.
g. Finally, calculate the Dry Matter as the ratio of the final Net Dry Slice Weight
(column 10) to the Net Fresh Slice Weight (initial weight (column 9) and expressed
as a percentage.
𝐷𝑟𝑦 𝑀𝑎𝑡𝑡𝑒𝑟 (%)=𝐹𝑖𝑛𝑎𝑙 𝑁𝑒𝑡 𝐷𝑟𝑦 𝑆𝑙𝑖𝑐𝑒 𝑊𝑒𝑖𝑔ℎ𝑡 (𝑔)
𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝑁𝑒𝑡 𝐹𝑟𝑒𝑠ℎ 𝑆𝑙𝑖𝑐𝑒 𝑊𝑒𝑖𝑔ℎ𝑡 (𝑔) ∗100%

5
References
González-Moscoso, S. 2014. Proposing minimum quality indices and improving ripening
protocol for imported mangos (Mangifera indica L.) to the United States for the
improvement of consumer quality. Univ. of Calif., Davis. MS Thesis.
Makani, O. 2013. A mango quality survey and sensory evaluation of mango (Mangifera indica L.)
cultivars. Univ. of Calif., Davis. MS Thesis.
Table-1: Proposed dry matter (DM) minimum quality index (MQI)
Cultivar
Country of Origin
Proposed MQI
(%DM)
‘Ataulfo’
Nayarit, Mexico
≤16.9
Brazil
14.4
‘Francis’
Haiti
≤16.7
‘Haden’
Sinaloa, Mexico
12.3
‘Kent’
Peru
12.0
Sinaloa, Mexico
≤15.0
‘Tommy Atkins’
Nayarit, Mexico
13.0
Guatemala
13.0
Ecuador
11.0
González-Moscoso (2014)

6
Appendix-I: Sample Data Sheet
Comments:
(1)
Sample
ID
(2)
Date
&
Time
(3)
Tray ID
(4)
Position
in
Tray
(5)
Weighing
paper
weight
(g)
(6)
Fresh Slice
Weight (Initial
weight) with
paper
(g)
(7)
Dry Slice
Weight with
paper-I
(After 24 hr)
(g)
(8)
Dry Slice
Weight with
paper-II
(Final weight)
(g)
(9)
Initial Net Fresh
Slice weight
(column 6-
column 5)
(g)
(10)
Final Net Dry
Slice weight
(column 8-
column 5)
(g)
(11)
Dry Matter (%)
[column 10/
column 9]*100
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16