Design and Development of a Cryogenic Decorticator Cum Grinder for Phytochemical Rich Myrobalan Fruit Powder

Abstract

Myrobalan (Terminalia chebula and Terminalia bellerica) fruits have many vital phytochemicals and nutraceuticals. These fruits have numerous medicinal uses in Ayurveda, Siddha, Unani, Tibetan, Chinese, and folklore medicines. Myrobalans are the essential constituents of the traditional herbal medicine named Triphala. Unit operations such as decortication and grinding are essential for proper utilization and value-addition of the myrobalan fruits. Due to lack of proper equipment, the decortication of the fruits is done manually using a hammer or stone. It is a labor-intensive and time-consuming process. It also increases the chance of contamination, making the product unsuitable for medicinal uses. After the decortication, the end products are ground to make powder. Currently, conventional methods are used for the grinding process. During the process, much heat is generated that denatures most of the heat-sensitive phytochemicals in the final product and makes it unsuitable for medicinal uses. Hence, there is a need to develop proper methods and equipment for optimum utilization of the myrobalan fruits. A new cryogenic decorticator-cum-grinding equipment was designed, developed, fabricated, and evaluated for myrobalan fruits to address the above issue. Various physical and engineering properties of the fruits, necessary for designing the equipment, were determined. Chemical and phytochemical properties were also determined. The equipment was designed using CATIA V5 (CAD, USA). It was fabricated with the support structure and contact parts made of mild steel and stainless steel (304 L). The equipment consists of a pre-cooling tunnel, decorticator, separator, and grinder. Liquid nitrogen was used in the pre-cooling tunnel, decorticator, and grinder sections to reduce the heat generated and loss of heat-sensitive phytochemicals during the operation. The performance of the equipment was evaluated, and the process parameters such as feed rate and liquid nitrogen dosage were optimized. The optimum grinding efficiency of 98.00% could be achieved at a 12.28 kg/hr feed rate and liquid nitrogen dosage of 0.72 L/kg of feed for T. chebula. Similarly, optimum grinding efficiency of 96.11% could be achieved at a feed rate of 12.86 kg/hr and liquid nitrogen dosage of 0.74 L/kg of feed for T. bellerica. The DPPH retention of the cryogenically ground powders of T. chebula and T. bellerica were 90.60 and 90.11%, respectively. The other phytochemical constituents, such as phenolic compounds, flavonoids, and tannin content, were higher in the cryogenically ground powders of T. chebula and T. bellerica than the powders obtained in the conventional method. Maximum iv retention of these phytochemicals, close to natural content, was observed. Various powder properties such as flowability, wall friction, oil and water holding indices, emulsion activities, stability, crystallinity, and surface morphology (SEM) were determined and compared. All these properties of the cryogenically ground powders were better than that of the conventionally produced powders suggesting the feasibility and proper working of the decorticator-cum-grinder. The cost economic analysis of the equipment was also done. The unit cost of the cryogenic decorticator-cum-grinder was ₹4,99,450.00 INR ($ 6,834.00 USD). The return on investment (ROI) of 911%, breakeven point (BEP) of 166 kg of powder production, and payback period (PBP) of 45 days on the initial investment cost suggested the economic feasibility and commercial viability of the equipment. The developed cryogenic decorticator-cum-grinder could be a possible solution for processing and value-addition of myrobalan fruits for increasing the income for sustainable livelihood of rural population dependent on the collection and sale of these fruits. It could also help in commercializing myrobalan fruit products for use in the herbal medicine industry. [math mode missing closing $]