Cashew apple
Cashew apple is a product of the cashew tree with a possible economic value. Today, in many countries where many cashews are grown (including Vietnam), in addition to the main product, cashew nuts, millions of tons of cashew apples are obtained in the harvest season. However, the cashew processing industry is only in a very minor position despite its great potential (the amount of cashew apple is often 8 to 10 times more than the amount of cashew nut).
Nutrient composition of cashew apple
Cashew apple is an easily digested and mashed sweet food. It contains a lot of water, rich in minerals and vitamins C, B1, B2, PP, etc. In particular, vitamin C content in cashew apples is 5 times more than in a lemon. Thus, cashew apple juice with a concentration of 12-14 degrees B, 10.15-12.5 grams of reducing sugars, and 0.35% acid (according to malic acid) can be obtained when pressing the fresh cashew apples. Cashew apples can be a competitor of other tropical fruits such as mango, papaya, and pineapple.
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Vietnam |
India |
Mozambican |
Brazil |
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Red fruits |
Yellow fruits |
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|
(1) |
(2) |
(3) |
(4) |
(5) |
(6) |
(7) |
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|
Moisture (%) |
85.92 |
86.38 |
84.5 |
87.8 |
85.03 |
|
85 - 90.4 |
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Lipids (g) |
0.3 |
0.27 |
|
0.1 |
0.2 |
|
0.02 |
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Protein (g) |
0.88 |
0.52 |
|
0.2 |
0.8 |
0.375 |
0.7 – 0.9 |
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Carbohydrates (g) |
0.86 |
0.98 (a)
|
11.6 |
8.62
|
10.6 - 0.08
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|
|
|
Reducing sugar (g) |
7.74 |
7.26 |
7.5
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|
|
|
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Cellulose (g) |
3.56
|
3.34 |
0.4
|
|
0.44
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|
2.5 (b) |
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Ash (g) |
0.44 |
0.51 |
0.3 |
0.2 |
0.32 |
0.3 |
0.19 |
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Calcium (mg) |
|
|
|
0.01 |
1 |
0.003 |
5-Feb |
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Phosphorus (mg) |
|
|
|
0.01 |
29.2 |
0.002 |
6.1 |
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Iron (mg) |
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|
|
0.2 |
0.29 |
0.003 |
0.4 – 0.7 |
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Carotene (Vit. A) (mg) |
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|
0.09 |
1.32 |
|
450 (c) |
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Thiamine (Vit. B1) (mg) |
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|
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|
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|
0 – 0.02 |
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Ascorbic acid (Vit. C) (mg) |
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|
|
261.5 |
285.8 |
187 |
372 |
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Niacia (Vit. PP) (mg) |
|
|
|
|
|
|
0.13 – 0.15 |
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Tannin (g) |
0.42 (d) |
0.48 (d) |
|
0.34 – 0.55 (d) |
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(*) Ingredients in 100g of fruit: (a) - mainly pectin; (b) - hemicellulose; (c) - international unit; (d) - cochin 1969, IRAF 1974 - cited by Ngo Tuan Ky
Source (1), (2): Tkatchenko, 1949; (3): Koening, quoted by Tkatchenko, 1949; (4): Indian Cashew Journal, 1967; (5): Lopes, 1972; (6): Goncalves de Lima, 1952; (7): Haendlex - Duverneuil, 1970.
Table – Vitamin content in some fruits
|
The type of cashew apple |
B1 0.000001g/100g
|
B2 0.0001g/100g |
C mg/100g |
P mg/100g |
Ca mg/100g |
Fe mg/100g |
|
Yellow cashew (1) |
|
98.75
|
239.56 |
11 |
41 |
3 |
|
Red cashew (1) |
|
128.75 |
186 |
11 |
41 |
3 |
|
Pineapple (2) |
80 |
20 |
24 |
11 |
16 |
0.3 |
|
Avocado (2) |
120 |
150 |
16 |
38 |
10 |
0.6 |
|
Banana (2) |
90 |
60 |
10 |
28 |
8 |
0.6 |
|
Lemon (2) |
40 |
|
45 |
10 |
14 |
0.1 |
|
Grapefruit (2) |
40 |
20 |
40 |
_ |
_ |
_ |
|
Tangerine (2) |
70 |
30 |
31 |
23 |
33 |
0.4 |
|
Orange (2) |
80 |
30.9 |
49 |
23 |
33 |
0.4 |
(1): According to Costa and Carvalho
(2): According to Hawk, Caer, Sumerson
However, cashew apples have the disadvantage of acrid taste because the chemical composition of the fruit contains tannin (the riper the fruit, the more acrid taste decreases). Also, the vitamin C content in the juice is significantly reduced under the influence of heating and storage time. The acrid taste can be removed from the fruit or pressed to get the juice and then remove the acrid from the juice. After pressing, the left residue accounted for 30-40% of the fruit. The fruit residue also contains about 9% protein, 4% lipid, 8% cellulose, 1% pectin. In addition, Calcium, Fe and P in the left residue are suitable for animal feed.
The method to remove the acrid taste of cashew apple
According to Jain et al (1954), steaming cashew apples with 2 - 6 kg pressure for 5 - 15 minutes (depending on the ripeness of the fruit and the tannin content in the fruit) can eliminate most of the bitterness. After steaming, the cashew apple must be thoroughly washed with water before processing.
It is also possible to remove the acrid taste by boiling cashews in 2% salt solution for 4-5 minutes, then rinsing with water thoroughly, giving the same results as steaming.
Table – The quality of juice from cashews that have been steamed and boiled with 2% salt solution
|
physicochemical criteria |
fresh cashew apple juice |
steamed cashew apple for 15 minutes |
boiled cashew apple in salt solution |
|
Refractive index |
14.2 |
13.4 |
13.4 |
|
Acid value (as Malic) % |
0.3 |
0.4 |
0.4 |
|
Tannin (%) |
0.3 |
0.07 |
0.04 |
|
Taste |
bitter and acrid |
light acrid |
no acrid |
(CFTRI) cited by Ngo Tuan Ky
The acrid taste of the juice from fresh cashews can be removed by treating the juice with gelatin (0.25 - 0.4%) and pectin (0.35%) and then filtering out the precipitates.
Table - Physicochemical properties of cashew apple juice before and after gelatin treatment (CFTRI)
|
physicochemical criteria |
cashew apple juice (not treated) |
cashew apple juice (treated) |
|
Refractive index |
12.5 |
10.5 |
|
Acid value % |
0.46 |
0.33 |
|
pH |
4.25 |
4.2 |
|
Ascorbic acid (mg) |
264 |
219 |
|
Tannin (%) |
0.32 |
0.03 |
Benefits of cashew apple
Cashew apples are used as food in a variety of ways. They can be eaten fresh or cut into thin slices, sprinkled with salt (or sugar) to reduce the acrid taste and then eaten. Besides, they are also used as raw materials for processing beverages, wine, jam, candy, etc. (in Brazil, India, etc.) or used in fruit cocktail parties with other tropical fruits (in Venezuela).
Below is a guide on how to process some types of cashew products:
+ Cashew juice (cashew apple)
+ Cashew syrup and concentrated cashew juice
+ Canned cashews, cashew candies and jams, cashew vinegar
+ Cashew wine
+ In addition, cashew apples can also be used to eat directly or have many applications in making medicine, making animal feed, making dry alcohol, fertilizer and biofuel.
Image - Cashew apple is processed into juice for direct use
Challenges of exploiting the benefits of cashew apples
Although there are technical know-hows to process different products from cashew apples, so far it has not been properly exploited to its great potential. For example, in India, Fenny production remains at the household level, the products produced are consumed locally. In Brazil, with an annual output of about 2 million tons of cashew apples, just 8 juice processing factories with a processing capacity of 80,000 tons of cashew apples each year. In Vietnam, there are also millions of tons of cashew apples harvested every year but almost unused.
The reasons for this restriction are:
- The cashew apples do not ripen at the same time, so the harvest is prolonged. Raw cashew apples produced by season are an obstacle for industrial production (with investment in modern equipment) and product consumption.
- Cashew apples wilt very quickly because the first harmful fermentation caused by fungi and pre-existing bacteria occurs within 24 - 36 hours after harvest (especially if crushed, the fruit cannot be kept for more than 1 day). Therefore, it is very difficult to transport and use cashew apples without using timely preservatives right after harvesting and transporting. Some authors have reported using benzoic acid and some chemicals as preservatives for cashew apples, thereby inhibiting harmful fermentation processes in cashew apples (Pruthi J.C., Rao B.A.S., Siddappa G.S., 1963).
- The cost of eliminating the bitter and acrid taste of cashew apples increases the cost of processed products, making them less competitive compared to similar products produced from other fruits such as mango, pineapple, etc.
REFERENCE
Thanh D.P. (2003). Cashew nuts - Production and Processing.
