Citric Acid Production From Pineapple Waste Through Solid-State Fermentation
Citric Acid Production From Pineapple Waste Through Solid-State Fermentation
Citric Acid Production From Pineapple Waste Through Solid-State Fermentation
Abstract
Citric acid is a naturally occurring organic acid widely used in the food, beverage and pharmaceutical industries as an acidulant
or a mild preservative. It has a worldwide annual demand of about three million tons and a local demand of 22 000 tons. At
present, the local demand in the country is supplied by imports. This study aims to develop an economically feasible and
environment-friendly process flow for the first citric acid plant in the country with an annual capacity of 4400 tons. Pineapple
waste has been chosen as raw material due to its abundance in the country. The process for the plant may be divided into three
parts: raw material preparation, solid state fermentation, and purification. Downstream processes include the use of a new
technology, the Simulated Moving Bed (SMB). The use of SMB was selected because of its reduced waste and water
requirement and higher productivity. The designed plant has total capital investment of 17.4 million USD. It has an attractive
internal rate of return of 20.7 % and a net present value of $15.6 million. It has a simple payback of 4.3 years and a discounted
payback period of 5.3 years.
Keywords: Citric Acid; Pineapple waste; Solid-State Fermentation
1. Introduction
Pharmac
uetical,,
etc
Deterge 10%
nt
20%
Other
food
(preserv
atives,
sour
flavor)
20%
4
3
2
Demand
Supply
0
2008 2009 2010 2011 2012
3. The Process
Pineapple waste containing about 65 % moisture is first
ground in a double runner mill at an optimum particle size of
2mm. It is then mixed with 3% methanol and 5ppm ferrous
sulfate heptahydrate crystals. This comprise the fermentation
medium. Meanwhile, the microorganism, Aspergillus niger
ACM 4992, is cultured with potato dextrose agar in an
inoculation tank, R-101, an anaerobic bioreactor. The
germination of the microorganism increase with increasing
temperature at a range of 23-30oC and the optimum pH for
the process is at 4.5.
Beverag
es
50%
[1]
[2]
[3]
Weight
25.8%
3818825.191
11.6%
1718471.336
2.3%
343694.2672
Piping
4.1%
611012.0306
Electrical
2.6%
381882.5191
Buildings
6.5%
954706.2978
Yard improvements
3.4%
496447.2749
10.3%
1527530.077
1.6%
229129.5115
Service facilities
Land
Cost, USD
Purchased equipment
Tot al di rec t pl an t c os t
Engineering and supervision
Construction expenses
10081698.5
8.5%
1260212.313
10.1%
1489341.825
12831252.64
Contractor's fee
4.4%
649200.2825
Contingency
8.8%
1298400.565
14778853.49
Worki n g c api t al
2596801.13
17375654.62
4. Optimization Studies
The fungal strain used, the additives tot he substrate and the
operating conditions used were based on a study by Tran, et
al which aimed to check for the operating conditions which
produced the highest yield from pineapple waste. To optimize
the production of citric acid from pineapple waste, several
strains of A. niger were tested. The strains were narrowed
down to three candidates, ACM 4992), ACM 4993 , and ACM
4994. Knowing the strain with the highest yield, the
experiment continued with the optimization of the
fermentation condition and medium composition. The effects
of methanol, pH, culture method, particle size, metal ions,
and time, were considered. Methanol addition contributed to
the increase of citric acid yield with A. niger strains. Methanol
is not used up by the microorganism but it helps with cell
permeability and citric acid excretion. It also suppresses the
production of oxalic acid, a by-product of Krebbs cycle. Iron
(II) ions help reduce trace metals and this in turn stimulates
the production of citric acid. For A. niger ACM 4992 only Fe2+
gave significant increase to the citric acid production, Mn2+
and Mg2+ had no effect, Zn2+ and Cu2+ slightly decreased the
production. (Tran, L.I., & D.A., 1998)
Equipment
Cost (US $)
Innoculation Tank
16,960.10
Heat Exchanger DI
8,652.36
Blower
13,902.99
5,865.17
Deionizer
60,664.50
Crusher
169,767.50
Pre-mixer
416,452.34
Fermentor
1,108,440.00
Filter
360,744.92
Evaporator
142,510.01
SMB
270,675.49
Crystallizer
832.89
Centrifuge
109,457.65
Dryer
1,053.35
Compressor
158,920.58
158,920.58
392,035.86
Product storage
71,514.26
Buffer Tank
204,806.25
Pumps
146,648.38
$
Cash Flow, USMillions
Cake storage
Total cost
3,818,825.19
Table 2. Purhased Equipment Breakdown
The citric acid will be sold at a price of US $ 1500 per ton, as
dictated by the current citric acid market, while the byproduct, pineapple waste biomass will be sold at a price of US
$ 50 per ton. The price of the biomass was based on the
biomass market with almost the same property as that of the
produced in the plant. This will amount to an annual sales
value of approximately US $ 7.8M. Operating costs include
labor, electricity, raw materials and utilities. The breakdown
of the operating costs is shown in the table below.
Methanol
387.82
FeSO4 7H2O
32.39
11,322.32
Steam (MP)
854,781.36
417,677.87
Site
664.39
(10.00)
9 10
Miscellaneous
SMB resin
(5.00)
Operating Year
Electricity
Equipment
Utilities
Cooling Water
5.00
(20.00)
Raw Material
154,043.83
10.00
(15.00)
Cost (US $)
Pineapple Waste
15.00
750,905.19
Labor
The process for the plant may be divided into three parts: the
raw material preparation, fermentation, and purification.
Solid-state fermentation has been selected because it has
low sensitivity to trace elements eliminating the need for
rigorous pre-treatment. It also has the shortest fermentation
period among other methods. Downstream processes include
filtration, evaporation, simulated moving bed (SMB)
purification, crystallization, centrifugation, and drying. The
use of SMB technology has been selected because of its
reduced waste and water requirement and higher productivity
per mass and feed and per unit time.
211,855.16
TOTAL
2,401,670.31
Table 3. Operating Costs Breakdown
It is assumed that 70% of the capital will come from bank
loans with an annual interest rate of 8% compounded
annually. The rest is equity. The breakdown of the loan and
equity is based on the usual bank agreements. The bank loan
is to be paid over a period of four years.
The internal rate of return and net present value were
computed on a basis of a lifetime of 10 years. The figure
below shows the payback period of the citric acid plant. It has
a simple payback period of 4.3 years and a discounted
payback period of 5.3 years after the start of operations.
7. Main References
7.1. Books and Articles
Euromonitor International. (2012). FRUIT/VEGETABLE
JUICE IN THE PHILIPPINES. Passport , 4-9.
Euromonitor International. (2011). Pineapple Market
Holds Steady in Face of Recession. Euromonitor , 24
Wu, J., Peng, Q., Arlt, W., & Minceva, M. (2009). Recovery
of Citric Acid from Fermentation Broth Using Simulated
Moving Bed Technology. Separation Science and
Technology .