Luffa Research Report
Post-harvest Treatments for Producing Sponges from
Immature Fruits of Luffa Gourd
Tammy L. Ellington and Todd C. Wehner
Department of Horticultural Science, North Carolina
State University, Raleigh, NC 27695-7609
Cucurbit Genetics Cooperative Report 19: 85-86
Luffa gourd (Luffa aegyptiaca Mill) is grown
in small areas for the production of sponges for cosmetics and
cleaning products. In eastern North Carolina, we usually plant
in mid April, and harvest weekly from mid October to mid November.
Sponges are produced by harvesting fruits that have turned brown
at the end of the season, then removing the seeds and skin from
the fruit, and drying the sponge.
Fruits that are green at harvest can be divided into
two categories. Fruits that have a dry, leathery skin that is
beginning to turn brown will be referred to as mature-green. Those
can be used in the same way as fruits that are brown at harvest.
Fruits that are still soft and have a bright green skin will be
referred to as immature-green. Luffa gourd is of tropical origin
and requires a long growing season. As a result, luffa growers
may harvest immature-green fruits when frost kills the plants
at the end of the season (usually October in eastern North Carolina).
Currently, there are no published data on the handling
and processing techniques of immature-green fruits for optimum
sponge quality. The objective of this experiment was to determine
how to use immature-green fruits.
Methods: In order to evaluate the handling of immature-green
fruits, 4 treatments were used: air drying, forced and heated
air drying, soaking in water, and soaking in a 10% bleach solution.
Those treatments will be hereafter referred to as air, dryer,
water, and bleach, respectively. Air involved hanging the sponges
on wires in a greenhouse (30 C day/20 C night). Dryer treatment
involved putting the sponges in a dryer with heated air (32 C)
forced through drying racks. The dryer was designed as a cucumber
seed dryer (Wehner and Humphries, 1994). Water treatment involved
soaking the sponges in tanks of water, with the water changed
daily. Bleach treatment involved soaking the sponges in tanks
of 10% chlorine b leach, with the solution changed daily.
The experiment was a randomized complete block design
with 2 years, 2 replications, and 1 fruit per treatment combination.
The fruits were treated for 1 to 18 days, and evaluations were
made 1, 4, 6, 8, 13, 15, and 18 days after harvest. A rating system
of 1 to 9 was used for evaluation of skin brownness (1-3 = light
green, 4-6 = brownish green, 7-9 = dark brown), peeling ease (1-3
= difficult, 4-6 = intermediate, 7-9 = easy), and sponge quality
(1-3 = poor, 4-6 = intermediate, 7-9 = excellent). In the first
year, data were not taken on the treatments involving water soaking
and bleach soaking after 13 days, because the fruits were disintegrating.
In the second year, data were not taken on the fourth day due
to scheduling difficulties.
Results: In the first year, skin brownness and ease
of peeling generally increased as the treatment time increased
(Table 1). Of the 4 treatments tested, air drying for at least
13 days provided the most usable sponges. The data were variable
due to the small number of fruits tested.
In the second year, water was consistently the best
treatment for ease of peeling (Table 2). Air was the best treatment
for promoting skin brownness. Dryer treatment was the best for
sponge quality. In general, at least 13 days in the dryer provided
the most usable sponge. Once again, the data were variable due
to the small number of fruits tested.
The differences between years can be explained by
the different stages of immature-green fruits used. In the first
year, the immature-green fruit were consistently more mature in
development than were those in the second year.
In conclusion, immature-green fruits can be used as
sponges if they are air dried for 2 to 3 weeks in a warm, dry
location. That treatment will cause the fruit skin to turn brown,
and it can then easily be peeled. Care should be taken to avoid
the immature-green fruits where the fibrous network has not begun
developing, or the dried fruit will not be usable as a sponge.
Future studies are needed to evaluate sponges produced from immature-green
fruits for strength and usable life relative to mature fruits.
Literature Cited
1. Wehner, T.C. and E.G. Humphries. 1994. A seed dryer
for cucumber seeds. Cucurbit Genet. Coop. Rpt. 17:54-56.
Table 1. Sponge usability in 1993 for immature-green
fruits of luffa sponge gourd after 4 post-harvest treatments on
skin brownness, ease of peeling, and sponge quality 1 to 18 days
after fruits were harvested from the vine.z
|
|
Days after harvest
|
|
Treatment
|
1
|
4
|
6
|
8
|
13
|
15
|
18
|
|
Skin brownness rating
|
|
Air
|
1
|
1
|
1
|
4
|
9
|
9
|
9
|
|
Dryer
|
3
|
5
|
2
|
6
|
6
|
5
|
6
|
|
Water
|
1
|
2
|
4
|
6
|
6
|
-
|
-
|
|
Bleach
|
2
|
2
|
3
|
5
|
5
|
-
|
-
|
|
Ease of peeling
|
|
Air
|
1
|
7
|
8
|
5
|
8
|
8
|
8
|
|
Dryer
|
3
|
2
|
6
|
6
|
6
|
6
|
7
|
|
Water
|
6
|
6
|
7
|
8
|
8
|
-
|
-
|
|
Bleach
|
7
|
6
|
5
|
8
|
6
|
-
|
-
|
|
Sponge quality
|
|
Air
|
1
|
5
|
4
|
5
|
8
|
6
|
6
|
|
Dryer
|
4
|
3
|
3
|
6
|
5
|
4
|
5
|
|
Water
|
5
|
6
|
6
|
6
|
6
|
-
|
-
|
|
Bleach
|
2
|
5
|
6
|
6
|
5
|
-
|
-
|
z Data are means of 2 replications of 1 fruit each. LSD
(5%) for row-column comparisons = 3.
Table 2. Sponge usability in 1995 for immature-green
fruits of luffa sponge gourd after 4 post-harvest treatments on
skin brownness, ease of peeling, and sponge quality 1 to 18 days
after fruits were harvested from the vine.z
|
|
Days after harvest
|
|
Treatment
|
1
|
4
|
6
|
8
|
13
|
15
|
18
|
|
Skin brownness rating
|
|
Air
|
1
|
-
|
7
|
5
|
6
|
6
|
6
|
|
Dryer
|
1
|
-
|
5
|
4
|
5
|
5
|
5
|
|
Water
|
2
|
-
|
2
|
3
|
3
|
3
|
3
|
|
Bleach
|
4
|
-
|
4
|
4
|
6
|
6
|
6
|
|
Ease of peeling
|
|
Air
|
2
|
-
|
5
|
5
|
4
|
5
|
8
|
|
Dryer
|
2
|
-
|
4
|
4
|
6
|
6
|
6
|
|
Water
|
2
|
-
|
6
|
7
|
8
|
8
|
9
|
|
Bleach
|
2
|
-
|
2
|
4
|
3
|
3
|
4
|
|
Sponge quality
|
|
Air
|
2
|
-
|
5
|
6
|
4
|
6
|
8
|
|
Dryer
|
2
|
-
|
6
|
6
|
6
|
6
|
7
|
|
Water
|
2
|
-
|
4
|
5
|
6
|
8
|
8
|
|
Bleach
|
3
|
-
|
2
|
4
|
4
|
4
|
5
|
z Data are means of 2 replications of 1 fruit each. LSD
(5%) for row-column comparisons = 2. |
