The cashew tree, Anacardium occidentale, was brought to India by the Portuguese from Brazil more than five centuries ago. It soon established itself as raw material for industry in the coastal districts. In Kerala, for example, the industrial capacity overgrew cashew crops in the state. In spite of high demand for the nuts, the area under cashew cultivation is not growing. But recent research is about to change farmers’ perspectives on cash from cashew.
First, the not-so-good news. The real calorific value of cashew nuts is about 16% less than shown on commercial packaging, say researchers from the US. The method used for measuring calorific values goes wrong because the cost of digesting the nuts is not taken into account.
Earlier, in vitro digestion studies had suggested that the plant cell wall limits the digestion of the nuts. Now, using a randomized crossover trial, with nine female and nine male volunteers, who had a controlled diet for 4-weeks and crossed over to the control/cashew diet for another four weeks, the researchers confirmed what was suspected. It is not only cashew, but all nuts whose actual calorific value is overestimated, say the scientists1.
Cashew gum: The cashew tree came to India after Ayurvedic traditions were well entrenched in society, but at a time when further innovations were limited. So it missed being included in our traditional herbal medicine. Scientists from Brazil and Spain say that cashew gum is useful for inflammation of the gums after dental operations in rats. Cashew gum suppresses the over-expression of the genes that mediate inflammation, they found2.
A team of scientists from Portugal recently reported that cashew gum can be used in soft tissue engineering3. They mixed cashew gum with gelatin to create a sponge-like gel that supports the growth of soft tissues. So we will see many laboratories looking for cashew gum for tissue and organ culture. The potential for economic partnerships between cashew farmers and biomedical entrepreneurs seems to be imminent due to the values found in cashew flowers, leaves and seed.
Cashew Flowers: Another team from Brazil reported that extracts of cashew flowers also have anti-inflammatory activity and that the ethanolic extract of the flowers can be used to treat lethal sepsis in diabetic rats4.
Cashew leaves: Scientists from Thailand report an easier way to extract phenolic antioxidants from the leaves of the cashew tree. Extraction using solvents is increased threefold if assisted by ultrasound, they say. The number of phenolic antioxidants also increased when they used ultrasound. The antioxidants were tested for their ability to protect against DNA damage5.
Another research team from Thailand reported that the ethanolic extract of cashew leaves has the potential to be used to treat male sexual dysfunction. Experiments with rats demonstrated the aphrodisiac quality of the extract. The team tested the extract for cytotoxicity and found it to be safe6.
Cashew seed oil: Since cashew seed oil has been traditionally used for malaria in South America, scientists tried the ethanolic extracts of cashew against the malarial parasite, Plasmodium falciparum. They find that cardol and 2-methylcardol derivatives from the extract are active against P. falciparum7. This, at a time when the parasite is becoming resistant to artemisinin, brings hope for malaria endemic regions.
Cashew shell liquid: Chinese scientists recently found that anacardic acid extracted from cashew nut shell liquid is effective against echinococcosis, a zoonotic disease prevalent all over the world. Though transmitted to humans by dogs and cats, a part of the life cycle of the Echinococcosis multilocularis is in cattle. In humans, often the disease goes undetected, but is responsible for morbidity in large populations. The researchers say that the compound is as effective as albendazole, used to treat infestations by the worm8.
Brazilian scientists have come up with another use for cashew shell liquid: as a method to control mosquitoes. Anacardic acid, extracted from the liquid, is highly effective in killing mosquito larvae within 24 hours, they found. Anacardic acid is easily degraded and is not harmful to humans9.
While all these reports are exciting for public health authorities, farmers in India may still hesitate. Cash for cashew will may have to wait till the research is developed further.
Cashew apple: There is, however, one report that spells immediate gain for the farmers. The cashew fruit is mostly wasted in Kerala, unlike in Goa, where it is used for making feni. A Sobhana, from the Cashew Research Station at the Kerala Agricultural University, Thrissur recently reported evaluating beverages and jams made from cashew fruit.
She evaluated thirteen varieties of cashew for acceptability as jams and beverages. She found the Poornima and Vridhachalam-3 varieties best for making beverages and jams10.
“KAU has earlier made and commercialised syrup, jam, pickle, candy, chocolate, carbonated drink and vinegar. We now have eight more products – halva, fruit bar, cake…”, says Sobhana.
Nuts are not the only source of cash for cashew farmers. Backward and forward integration of resources from cashew plantations needs to be undertaken by the Cashew Export Promotion Council of India to entice more farmers to cultivate good varieties of cashew and to persuade them to undertake cashew cultivation to meet cashew industry demand.
- Nutrients 11, 33 (2019)
- Int. J. Biol. Macromole. 128: 934-940 (2019)
- Macromol. Mater. Eng., 304 (3): 1800574 (2019)
- J. Ethnopharmacol. 236: 345-353 (2019)
- J Food Sci Technol. 56 (4): 1785-1792 (2019)
- BioMed Research International, 1459141 (2019)
- Environ. Sci. Poll. Res., 26 (6): 5514-5523 (2019)
- Veterinary Res., 50: 3 (2019)
- Brazilian J. Pharmacognosy 29 (1): 36-39 (2019)
- Indian J. Horticulture, 76 (1): 155-161(2019)
Udham P K
Freelance Writer, Pune
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