A literature review of cashew apple processing

Abstract

The cashew tree, a tree adapted to tropical areas was introduced in Africa by European explorers. Its cultivation in some African countries has been done to stop the advancing Sahara desert and to reduce soil erosion. The cashew fruit consists of a nut being the real fruit, and a fleshy apple which is considered the pseudofruit. The nut represents the major point of interest in cashew tree cultivation. Despite being a commodity of international trade, cashew apple suffers from low commercial interest. As a result, millions of tons of cashew apple rot in orchards without any form of processing every year. Gradually, its excellent properties are attracting the attention of the scientific world and industrialists with a view to enhancing its commercial and food value. This review reports different methodologies of transforming cashew apple. Some potential products include juice and potential cocktails. Juice clarified by tangential microfiltration was almost cleared of tannins, giving good clarity and a pleasant taste. A stabilized cocktail of cashew apple and pineapple juices using 10% ginger aqueous extract was judged good as it retained prime quality for 7 days at 4 - 5 °C, with significant improvement of vitamin C and protein content (p ≤ 0.05). Obtaining an amber dry wine of 12.6% alcohol with no significant difference (p < 0.05) from commercial grape wine was demonstrated using Saccharomyces cerevisiae as a fermenting agent. Ethanol of 97.8% purity was also obtained by immobilized cells of S. cerevisiae on silica gel. Edible vinegar of 4% acidity with similar characteristics as commercial varieties was produced from the juice. Jam and a viscous syrup of 80 °Brix which was found to be rich in glucose and fructose was also produced. A generator powered by 6% cashew apple biofuel with the rest being gasoline revealed reduced fuel consumption compared to the use of gasoline alone, though engine behavior during its operation was a concern. Also, cashew apple flour has been used for the manufacture of composite biscuit formulated with or without wheat flour. Thus, cashew apple could become a source of additional incomes for peasants by being the origin of creation of companies through these various developed technologies.