Increased Revenue with High Value-Added Products from Cashew Apple (Anacardium occidentale L.)—Addressing Global Challenges

The Cashew Pseudofruit (Anacardium occidentale): Composition, Processing Effects on Bioactive Compounds and Potential Benefits for Human Health

The fruit of the cashew, a tree belonging to the family Anacardiaceae, is composed of approximately 10% nut (cashew) and 90% stalk or pseudofruit, usually discarded in situ and fermented in the soil. This review identifies cashew pseudofruit's physicochemical characteristics and bioactive compounds and their possible relationship to health benefits. Different processing techniques have been used to preserve the pseudofruit, and the effect of these techniques on its nutrients is also reviewed in this work. Cashew is a highly perishable product with moisture content above 80% w/w and 10% w/w sugars. It also has a high content of polyphenols, flavonoids, and tannins and high antioxidant properties that are best preserved by nonthermal processing techniques. The pseudofruit presents the high inhibitory activity of α-amylase and lipase enzymes, has anti-inflammatory and body weight reduction properties and healing activity, and controls glucose levels, insulinemia, and insulin resistance. For all these reasons, cashews have been promoted as a propitious food/ingredient for preventive and therapeutic management of different pathologies such as diabetes, dyslipidemia, obesity, hypertension, fatty liver, and acne. Moreover, it has positive effects on the intestinal microflora, among others. This pseudofruit has a high potential for the development of functional foods.

Valorization of food wastes with a sequential two-step process for microbial β-carotene production: A zero waste approach

Here, two consecutive β-carotene fermentation processes were carried out with Rhodotorula glutinis yeast in the growth media obtained from orange and grape wastes. Firstly, waste biomasses were subjected to hot water extraction. Effects of waste type, drying pretreatment, particle size and solid/liquid ratio on the total concentration and yield of sugars recovered were tested. The highest sugar concentration was obtained by the hot water extraction of fresh grape pomace as 61.2 g total reducing sugars (TRS)/L at a solid/liquid ratio of 100 g/L. In the first fermentation process, effect of solid/liquid ratio (initial TRS concentration) on β-carotene production pattern of R. glutinis was investigated in the media obtained directly by hot water extraction of the wastes. Microorganism and β-carotene concentrations increased with increasing solid/liquid ratio (range 10-100 g/L), and the microbial growth data fit the Monod model well for all cases. Maximum β-carotene concentration in the growth medium obtained from hot water extraction of 100 g/L of grape pomace was determined as 5988.6 mg/L. In the second fermentation process, β-carotene was produced in the acid hydrolysate of extraction residues. 10.1 g/L and 6.7 g/L of TRS was obtained after acid hydrolysis of orange and grape residues, respectively, and the highest β-carotene concentration of 370.0 mg/L was found in the medium of hydrolyzed orange peel extraction residue. Total β-carotene production increased to 1777.1 and 3279.6 mg/L (26% and 4.9% of increase) after the second fermentation step. 85.3% and 80.2% of reduction in orange and grape waste weights were observed at the end of the process, which was an indicator of efficient waste biomass disposal. Two sequential β-carotene fermentation steps offered significant advantages in terms of both efficiency and a zero waste approach.

Mitigation of cashew apple fruits astringency

The cashew apple is a tropical pseudo fruit, with high fiber content, high nutritional value, and therapeutic compositional profile. Consuming cashew apples can help with several health-related problems, such as obesity, stomach ulcers, and gastritis. It has even demonstrated anti-tumor and anti-carcinogenic effects, and its antioxidants can help with wound-healing. Despite such benefits, the cashew apple is frequently considered as waste generated by cashew nut industries, since its commercial applications are restricted by the astringency and poor storability. This astringency is primarily due to the presence of tannins; and a lack of proper, efficient, and economical astringency reduction strategy is accountable for major waste generation. This review compiles pieces of information on the causes of astringency, as well as tannin reduction methods, such as clarification, thermal treatments, microfiltration, and fermentation. These methods aim to either just reduce tannin content or to valorize this by-product in a less-astringent better product. Both routes will eventually help with the better utilization of said organic food waste, which is critical for sustainable development.

Potential application of modified date powder by microwave radiation, ultrasonication and chemical pretreatments as coffee substitute: its biochemical properties and consumer preferences

To consider the suitability of modified date powder as a coffee substitute, the biochemical and antioxidant properties of date powder were modified by hydrochloric acid-ethanol (HAE), alkaline hydrogen peroxide (AHP), combined with ultrasound (U) microwave (MW) radiation. The results showed that the highest antioxidant activity was observed in HAE and HAE-U treated date powders. The total flavonoid content of the date powder increased by 40.8% and 100% in response to the AHP-MW and HAE-U treatments, respectively. Fourier transform infrared spectroscopy did not show any abnormal or unknown peaks in the analyzed range of the treated samples. Therefore, modification of biochemical and sensory properties of date powder by chemical and irradiation treatments did not have a detrimental effect on changing the structure of its chemical compounds or the formation of harmful compounds in it. Sensory evaluations showed that replacing coffee powder with modified date powder by up to 25% did not have significant effects on the sensory properties of the coffee drink. Finally, the results showed that modifying the biochemical and antioxidant properties of date powder by the HAE method as coffee substitute can increase the nutritional properties of coffee drinks while also reducing the expenses of the coffee industry.

Graphical abstract

Economic viability of value-added cashew products processed in Southeast zone, Nigeria

The "Agricultural Promotion Policy (2016-2020)" is an initiative of Nigeria's government, designed to create jobs and wealth for participants in the agricultural value chains through value addition to export crops such as cashew. However, it is not known how cashew processors have exploited this opportunity to improve their economic returns from value-added cashew products, processed in the Southeast zone, Nigeria. Consequently, this study analysed the economic viability of value-added cashew products processed in the Southeast zone of Nigeria. Specifically, the objective was to determine the cost-benefit analysis, rate of return on investment, net income, and variability of value-added cashew products processed in the Southeast zone, Nigeria. A descriptive research design involving a cross-sectional survey of 353 randomly sampled participants was administered with a structured questionnaire. Ratio statistics, gross margin, benefit-cost ratio analysis, rate of return and ANOVA were applied to analyze the data. The results show that variable cost constitutes >96 but ≤98% of the total cost of cashew value addition. The average net income from 1 kg of value-added cashew products is profitable with cashew kernel yielding the highest net income (N2,724.4 (US $7.6) > cashew nut (N2,547.9 (US $7.1)) > both cashew products (N2,340.4 (US $6.5)). The benefit-cost ratios for 1 kg of value-added cashew nut and cashew kernel were slightly higher (1:1.4) respectively than that of both cashew products (1:1.3), suggesting that value-added cashew products deliver positive net income to the processors. Equally, the rate of returns (RORs) for 1 kg of value-added cashew products yield the highest (38.1%) in cashew kernel > cashew nut (37.4%) > both cashew products (34.1%). The coefficient of dispersion (COD) in revenue and cost of value-added products shows the least risk in cashew kernel (0.097) and the highest risk in both cashew products (0.122). The study provides empirical evidence for potential small and medium-scale investors to make an informed investment decision about value addition to cashew products. It is recommended that government should encourage people to engage in value addition to cashew products because of its high rate of return, and assist processors with credit to procure modern processing equipment to enhance profitability and income generation.

Biotechnological valorization of cashew apple juice for the production of citric acid by a local strain of Aspergillus niger LCFS 5

Background

This work investigates the production of citric acid from cashew apple juice, an abundant waste in the processing of cashew, using a local strain of Aspergillus niger and the application of the citric acid as a coagulant for the production of soy cheese. Fungal isolates were obtained from a cashew plantation in Ogbomoso, Nigeria, using potato dextrose agar. Further screening was undertaken to determine the qualitative strength of acid production by the fungi on Czapek-Dox agar supplemented with bromocresol green, with the development of yellow zone taken as an indication of citric acid production. Thereafter, the best producing strain was cultivated in a cashew apple juice medium.

Results

Out of 150 fungal isolates generated from the cashew plantation, 92 (61.3%), 44 (29.3%) and 14 (9.3%) were obtained from cashew fruits, soil and cashew tree surfaces, respectively. Different strains of fungi isolated include Aspergillus niger, A. flavus, A. foetidus, A. heteromorphus, A. nidulans and A. viridinutans. The isolates produced yellow zonation of 0.4–5.5 cm on modified Czapek-Dox agar; the highest was observed for a strain of A. niger LCFS 5, which was identified using molecular tools. In the formulated cashew apple juice medium, the citric acid yield of LCFS 5 ranged 16.0–92.8 g/l with the peak obtained on the 10th day of fermentation. The citric acid produced was recovered using the double precipitation method with Ca(OH)₂ and H₂SO₄ having ≈ 70% purity of citric acid on HPLC. The citric acid acted as a coagulant to produce soy cheese with 66.67% acceptability by panelists.

Conclusion

This work has extended the frontiers of valorization of cashew waste by a strain of A. niger to produce citric acid in high yield, with potential application in food industries.