Orange fruit wastes (OFW) can be an important by-product
in the processing fruit plants, which produce mainly manufactured
juice and essential oils. Several chemical bromatological
variables of
both fresh and fermented OFW were investigated to characterise
the nutritive and fermentative potential for silage
making.
Direct ensiling technology without using additives is an
alternative method that can provide a well preserved forage for
animal nutrition at low cost, but the alcohol
content was comparatively high in relation with the water soluble
carbohydrate content of the forage before ensiling.
The aerobic deterioration of the laboratory silage
samples ocurred without the visible growth of mould over the
surface of the end product during the aerobic stability test. The OFW
– leucaena silage showed high alcohol content. On the other
hand, silage treatments with OFW plus 0,5% urea and OFW – fish
(2:1) have adequate chemical propierties and can be recommended
to farmers.
Key words: orange fruit wastes, ensilage,
chemical composition
Ensilaje de desechos de naranja empleando diferentes
tratamientos
Resumen
Los desechos de naranja pueden ser un importante
subproducto en las plantas
procesadoras para obtener el jugo y los aceites esenciales.
Varios parámetros bromatológicos, tanto del
material fresco como del fermentado, fueron investigados para
caracterizar el potencial nutritivo y fermentativo de los
desechos de naranja con vistas a la producción de ensilajes.
El ensilaje directo sin el uso de aditivos es un
método
alternativo, pero se presenta un alto contenido de alcohol en
relación con los carbohidratos
solubles del material inicial. El deterioro aeróbico
ocurrió sin el crecimiento, visible a simple vista, de
mohos sobre la superficie del ensilado durante el ensayo de
laboratorio.
El ensilaje mixto de desecho de naranja – leucaena
presentó un alto contenido de alcohol.
Por otra parte, el tratamiento que emplea urea al 0,5% y
el de la proporción desecho de naranja – pescado
(2:1) mostraron adecuadas propiedades químicas y
podrían ser recomendados a los productores.
Palabras claves: desechos de naranja, ensilaje,
composición química
Citrus of all species are widely grown in tropical and
subtropical regions. The fruits are used mainly as dessert or
breakfast fruit and for making juices and other citrus products.
Citrus production in the producing countries is increasing
(Arribas, 2001).
Brazil and the United States account for 93 percent of
world orange juice production. In particular, the state of Sao
Paulo in Brasil and
Florida in the United States are the dominant producing areas for
orange juice. Mexico is the third largest world orange producing
country followed by Spain, China, and
Italy. Other significant orange producing countries include South
Africa, Israel, Egypt,
Iran, Cuba, Costa Rica,
Belize, Japan, and Australia (Spreen, 2000).
Livestock production in Cuba is limited by fodder
shortage during the dry season. To face this problem, man can
apply different strategies such as the utilisation of by-products
and storing forage from wet season surplus.
It has been proved that a rational use of by-products
allows to eliminate the myth that supplementation may be carried
out only through imported cereals and that their use as food for
animal production may contribute to the conservation of the
environment (Ojeda and Cáceres, 2002).
Due to the perishable property of surplus fruit during
seasons of overproduction in tropical countries, it would be
convenient to develop methods of preservation that would enable
these plant material to be utilised as animal feeds for longer
periods of time (Aguilera et al., 1997).
It is reported a yearly world production of 106 millions
tons of citrus fruits (FAO, 2001). The orange fruits represented
the 63 % of the world citrus production.
However it is processed yearly 600,000 tons of fresh
citrus fruits to produce juice, in six Cuban plants, and the use
of fresh citrus fruit wastes for animal nutrition is generalised
today in our country. Often, this by-product is under-utilised
causing some local environment pollution problems.
On the other hand, the production potential of the main
fishing by-products in Granma Province is over 6,000 tons per
year (Miranda, Otero and Cisneros, 2001).
Fish by-products are usually obtained from inedible
whole fish or from waste in fish processing industries. This is
an excellent source of protein and minerals for livestock, mainly
for cows that have recently calved and for high-yielding
cows.
The ensiling of the by-products, using molasse and other
easily available feeds rich in fermentable carbohydrates, such as
molasses, sweet potatoes, cassava roots, is a simple appropriate
method of conservation which has been successfully applied
recently in some countries. In all cases, the maximum amount of
fish wastes that can be included in the silage should be 50% with
a dry source of carbohydrates and much lower, about 10%, with
fresh sources (Chedlyl et al., 1999).
Waste is an inevitable consequence of the food industry.
Appropriate handling of waste has become an essential part of
modern processing management. As concerns over the environment
have increased, progresses which generated lucrative products,
but have attendant unmanageable waste problems, can become
unaffordable because of prohibitive disposal cost (
Rodríguez, Fuentes and
Díaz, 2003).
Environmental goods (natural resources and biophysical
conditions) have gradually turned into an economic variable. Its
consideration in the context of industry performance leads to
redesign the processes of production in line with the so-called
integral environmental technology.
So, it is important to assess the ensiling
characteristics of fresh OFW from Valencia variety in order to
propose its utilisation for silage making.
Plant material:
Fresh OFW of Valencia variety from the plant of
Contramaestre in Cuba’s Eastern region was used for the
silage experiments from January to April 2003 and
2004.
Chemical analysis and laboratory silage
To assess ensilability, three methods were followed up:
I) The water soluble carbohydrates content, II) A biolgical rapid
fermentation test with chopped plant material in aqueous
suspension, and III) Silage preparation was modelled in
microsilos.
Chemical parameters to characterise the fresh OFW before
ensiling and fermentation to characterise the silage quality were
determined as described Revuelta (2000), Kovátsits (1985)
and Weissbach & Laube (1964).
Experimental design
Treatments were: OFW without additives, OFW plus 0,5%
urea, OFW – Leucaena (1:1), and OFW – fish (Oreochromis
aereus) of non commercial size desintegrated
(2:1).
The experiment was analysed as a simple design
completely randomised with five-replication for each
treatment.
The 45% of orange fruits of Valencia variety on basis of
fresh weight are available as by-product (bagasse, peel and
seed), which is considered as solid wastes in the processing
plant of Contramaestre to produce juice (table 1).
Table 1: Chemical bromatological | |
Variable | Content |
Before ensiling | |
Yield, g / Kg FM | 450 |
Dry matter, g / Kg FM | 182,5 |
Ash, g / Kg DM | 63,0 |
Crude protein, g / Kg DM | 53,8 |
Crude fibre, g / Kg DM | 164,0 |
Ethereous extract, g / Kg DM | 20,4 |
Water soluble carbohydrates, g / Kg | 45,80 |
pH (initial) | 4,74 |
pH ( Pieper test after 44 hours of incubation | 3,10 |
After ensiling | |
pH | 3,10 |
(a) mL NaOH 0,25 mol / L to pH= | 8,6 |
(b) mL NaOH 0,25 mol / L to pH= 6,0 | 10,2 |
Index of fermentation quality = a / b | 0,84 |
Alcohol, g / Kg FM | 41,8 |
NH3 – N in % total N | 5,4 |
Aerobic stability test, g C02 / Kg | 35,2 |
The chemical and bromatological composition of fresh and
fermented OFW has shown that this plant material is a potential
feed source in animal livestock. So, its use in feeding formulas
for ruminant or monogastric animals is an attractive proposition
from technical and economical points of view (Alvir et al., 2001,
Ítavo et al., 2000 a,b,c, Domínguez, 1995, and
Valenciaga et al.,2005).
In addition, ensiling citrus waste has advantages over
traditional drying, in that less energy is used, cost of
processing is much reduced and there is improvement of
palatability.
This waste is palatable to cattle and mature cows, when
they are accustomed to the feed, consume about 10-15 kg per day.
Because of the high water content and the perishable nature of
the waste, economically it can only be used close to the
processing plant.
The fresh OFW had a low dry mater, crude fibre and crude
protein content and a high water soluble carbohydrate
concentration. The biological rapid fermentation test (Pieper,
1992) indicated a high potential acidity of fresh OFW (pH <
3,6) favourable for a natural conservation process, probably due
to the content of citric and other organic acids present in the
fruit.
Efficient silage fermentation is characterised by a fast
pH decline during the initial stages of ensiling. The OFW silage
used had a characteristic acid smell typical of very well
preserved silage, but alcohol odour was detected (table
1).
The fermented food showed a low pH and proteolysis and a
high index of fermentation quality (> 0,76) and alcohol
content. In this case occurred the aerobic deterioration without
the visible growth of mould over the surface of the silage
samples during the aerobic silage test.
Micro-organisms such as mould, bacterial and yeast would
cause the aerobic changes. Similar fermentative characteristics
such as pH and alcohol content presented the sugar beet silage
(Laube cited by Nehring, 1972).
pH is a key criterion to evaluate silage
fermentation.
Generally the lower the pH, the better preserved and
more stable is the silage. The critical pH that affects growth of
clostridium depends on the water activity of the fermentation
medium; with decreasing water activity the sensitivity of these
micro-organisms to acidity increases. Therefore, the dry matter
content of the forage affects the pH required for a quality
silage.
The products of fermentation and the osmolarity can be
used as indicators of silage quality (Zierenberg, Friedel and
Gabel, 2002).
Alcohol is a common, usually minor fermentation product
in ensiled forages, the major product being lactic acid.
Occasionally, high levels of alcohol are found in silages. The
micro-organisms responsible for alcohol fermentation as well as
the implications of feeding alcohol silages to Livestock remain
to be investigated in our conditions.
Adition of urea or fish prior to ensiling prevented high
alcohol levels of the fermented OFW (Table 2). It is important
because high contents of alcohol in silages can limit the
intake.
Tab. 2. Chemical composition of orange fruit waste
silages under different treatments
Treatments | A | B | C | |
1) pH-Value ( Pieper Test after 44 hours of | 3,25 | 3,90 | 4,06 | |
2) pH-Value ( Silage ) | 3,51 | 4,20 | 4,17 | |
3) ml NaOH 0,25 mol/L to pH=5,0 (a) | 5,7 | 4,6 | 6,1 | |
4) ml NaOH 0,25 mol/L to pH=6,0 (b) | 7,2 | 7,3 | 9,3 | |
5) a/b | 0,79 | 0,63 | 0,66 | |
6) NH3-N, % | 0,011 | 0,039 | 0,024 | |
7) Alcohol, % | 1,00 | 2,46 | 0,22 | |
8) Crude protein, % DM | 13,37 | 13,50 | 30,70 |
A: OFW plus 0,5% urea, B: OFW – Leucaena (1:1), C: OFW –
fish (2:1)
In order to increase farm incomes from livestock in
developing countries, an adequate low-cost feeding system must be
developed (Chedly et al., 1999 ). Making silage from agricultural
and agro-industrial such as citruspulp and fishery by-products is
a system, which offers considerable potential to improve farm
incomes and profits.
In conclusion, direct ensiling technology without using
additives is an alternative method that can provide a
well-preserved forage at a low cost to be used as animal feed for
longer periods of time; but it is shown here a high bioconversion
process of the soluble carbohydrates into alcohol compounds
typical of alcoholic fermentation silage pathway. On the other
hand, silage treatments with OFW plus 0,5% urea and OFW – fish
(2:1) have adequate chemical propierties and can be recommended
to farmers.
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By
Dr. Danilo Revuelta Llano, Ing.
Duniesky Mosquera López
Lic. Félix Cuba Mora
Universidad de Granma, Cuba