Valorization of Peanut Skin as Agricultural Waste Using Various Extraction Methods: A Review

Peanuts (Arachis hypogea) can be made into various products, from oil to butter to roasted snack peanuts and candies, all from the kernels. However, the skin is usually thrown away, used as cheap animal feed, or as one of the ingredients in plant fertilizer due to its little value on the market. For the past ten years, studies have been conducted to determine the full extent of the skin's bioactive substance repertoire and its powerful antioxidant potential. Alternatively, researchers reported that peanut skin could be used and be profitable in a less-intensive extraction technique. Therefore, this review explores the conventional and green extraction of peanut oil, peanut production, peanut physicochemical characteristics, antioxidant activity, and the prospects of valorization of peanut skin. The significance of the valorization of peanut skin is that it contains high antioxidant capacity, catechin, epicatechin resveratrol, and procyanidins, which are also advantageous. It could be exploited in sustainable extraction, notably in the pharmaceutical industries.

Orange Pomace and Peel Extraction Processes towards Sustainable Utilization: A Short Review

More than 58 million metric tonnes of oranges were produced in 2021, and the peels, which account for around one-fifth of the fruit weight, are often discarded as waste in the orange juice industry. Orange pomace and peels as wastes are used as a sustainable raw material to make valuable products for nutraceuticals. The orange peels and pomace contain pectin, phenolics, and limonene, which have been linked to various health benefits. Various green extraction methods, including supercritical carbon dioxide (ScCO₂) extraction, subcritical water extraction (SWE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), are applied to valorize the orange peels and pomace. Therefore, this short review will give insight into the valorization of orange peels/pomace extraction using different extraction methods for health and wellness. This review extracts information from articles written in English and published from 2004 to 2022. The review also discusses orange production, bioactive compounds in orange peels/pomaces, green extractions, and potential uses in the food industry. Based on this review, the valorization of orange peels and pomaces can be carried out using green extraction methods with high quantities and qualities of extracts. Therefore, the extract can be used for health and wellness products.

Composition of Crude Palm Oil Extracted Using Hot Compressed Water Extraction

Extraction process are one of the critical units in palm oil milling process which dictates its efficiency. In this study, hot compressed water extraction (HCWE) is utilized for the crude palm oil (CPO) extraction. With regards to CPO quality, the extracted CPO using HCWE was analysed based on overall composition, triacylglycerol (TAG) composition and fatty acid profile composition. This is to evaluate the possible product degradation during the process. From the results, the CPO extracted using HCWE process contain low FFA of 0.15±0.01% and low DAG of 2.145% which reflect to higher quality of CPO. This CPO also show the equal mixture of saturated and unsaturated fatty acid composition at 50.63% and 49.93% respectively, within the CPO composition range in the literature. No significant changing of the fatty acid composition is observed between CPO extracted using HCWE and commercial CPO indicated that no possible undesired reaction during the extraction process. HCWE is a promising method for screw press system replacement, but the economic analysis is essential to evaluate its prospective.