Abstract
The tiger nut is the tuber of Cyperus esculentus L., which is a high-quality wholesome crop that contains lipids, protein, starch, fiber, vitamins, minerals and bioactive factors. This article systematically reviewed the nutritional composition of tiger nuts; the processing methods for extracting oil, starch and other edible components; the physiochemical and functional characteristics; as well as their applications in food industry. Different extraction methods can affect functional and nutritional properties to a certain extent. At present, mechanical compression, alkaline methods and alkali extraction–acid precipitation are the most suitable methods for the production of its oil, starch and protein in the food industry, respectively. Based on traditional extraction methods, combination of innovative techniques aimed at yield and physiochemical characteristics is essential for the comprehensive utilization of nutrients. In addition, tiger nut has the radical scavenging ability, in vitro inhibition of lipid peroxidation, anti-inflammatory and anti-apoptotic effects and displays medical properties. It has been made to milk, snacks, beverages and gluten-free bread. Despite their ancient use for food and feed and the many years of intense research, tiger nuts and their components still deserve further exploitation on the functional properties, modifications and intensive processing to make them suitable for industrial production.
Highlights
The tiger nut, known as the “underground walnut”, grows all over the world because of its high yield and broad prospects for comprehensive utilization
Some innovative techniques have been established for the sustainable and viable recovery of the oil, such as gas-assisted mechanical expression (GAME), mechanical compressing with enzyme assistance (MEEA), microwave-assisted extraction (MAE), microwave-ultrasonic assisted aqueous enzymatic extraction (MUAAEE), supercritical carbon dioxide fluid extraction (SC-CO2) and subcritical n-butane extraction (SBE)
SE: Soxhlet extraction; ME: mechanical expressing; GAME: gas assisted mechanical expression; MEEA: mechanical compressing with enzyme assistance; MAE: microwave-assisted extraction; MUAAEE: microwave-ultrasonic assisted aqueous enzymatic extraction; SC-CO2: supercritical carbon dioxide fluid extraction; SBE: subcritical n-butane extraction
Summary
The tiger nut, known as the “underground walnut”, grows all over the world because of its high yield and broad prospects for comprehensive utilization. The tiger nut is the tiny tuber of Cyperus esculentus L., which can be roasted and used to be sweetmeat in Egypt [1] It is an important representative crop of the Spanish Mediterranean region, with an annual production of 9000 metric tons [2]. It has many nutrients that can be deeply explored and contains 22.14–44.92% lipids, 3.28–8.45% proteins, 23.21–48.12% starch, 8.26–15.47% fibers and 1.60–2.60% ashes [4]. It contains bioactive substances such as organic acids, alkaloids and phenols [5]. The nutritional value of tiger nut oil is similar to olive oil [6] It contains a lot of starch—a renewable and low-cost food ingredient [7]. People have made some contributions in its componen properties and product development, but the breadth and d
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