Abstract
The purpose of this study is to improve microbiological qualities of black tiger nut tubers. Thereby, black variety of tiger nut tubers (Cyperus esculentus) were differently processed in ascorbic acid and alkaline (Ca(OH)2 and Kanwa (alkaline calcium carbonate locally used to soften vegetable)) solutions at different concentrations and temperatures. The effect of these treatments on the water content (swelling), soluble loss, dehulling efficiency and microbial load was investigated. Water content or swelling of the tiger nut soaked in acid and alkaline solutions can be predicted by Peleg model like with brown variety.of C. esculentus tubers. This swelling lead to enhance dehulling efficiency of tuber but caused soluble solute loss overall at the highest temperature of soaking in vitamin C solution. Like soaking in water, the constant of Peleg (k1) decrease with the increase of the temperature of soaking, whereas the constant of capacity of Peleg (k2) is approximately 0.018% for all the conditions. Dehulling efficiency also increased with increasing temperatures (65% at 20°C to 70% at 60°C) for tiger nut tubers soaked in water (0 g/L), dehulling efficiency appeared most strongly affected by concentrations and temperatures of soaking solutions. Like dehulling efficiency, ascorbic solutions has given the best results in term of reduction of microbial load compared to the other soaking solutions. This reduction is considerable at the higher temperatures, reaching a maximum of 4.8 log reduction. Soaking and dehulling treatments gave to black tiger nut tuber effective decontamination in term of microbial load and obtained good microbiological quality for final process.
Highlights
Black variety of tigernut tubers (Cyperusesculentus) are used for production of vegetable milk or few data are available in literature concerning pretreatment of tubers, extraction and biochemical composition of milk [1a-4]
Soaking is a long stage process in which the goal is the swelling of tiger nut tubers
The kinetics absorption of solution by black tiger nut tubers at various temperatures and concentrations of ascorbic acid, Kanwa and Ca(OH)2 showed that the rate of absorption of water increased with the temperature of soaking like described by Djomdi et al [1b]
Summary
Black variety of tigernut tubers (Cyperusesculentus) are used for production of vegetable milk or few data are available in literature concerning pretreatment of tubers, extraction and biochemical composition of milk [1a-4]. High level of microorganisms such as bacteria and moulds (more than 109cfu/ml) have been detected in it; limiting its shelf life (less than 24 hours) [5,6,7] These micro-organisms originate from the rugous surface of the tuber where they are encrusted in the anfractuosities of the collenchyma sleeve [6,7,8]. Tubers soaked in water during several hours undergo a turgescence which results in an easy elimination of the tuber external skin [9, 10]. This turgescence is not observed with hypochlorite solution after 48 hours, suggesting the processing time is not sufficient. It proves to be important to test treatments having given convincing results with other raw Auctores Publishing – Volume 4(6)-069 www.auctoresonline.org ISSN: 2637-8914
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
