Physico-chemical Characterization of Granulated Sugar from Coconut (Cocos nucifera L.) Inflorescence Sap Cultivars and Sugar Cane in Côte d'Ivoire

Abstract

Aims: To evaluate and compare some physico-chemical characteristics of powdered sugar from the inflorescences of three of the most widespread coconut cultivars in Côte d'Ivoire compared to sugar from cane sugar to diversifying coconut exploitation in Côte d'Ivoire. Experimental Design was Used: The sap was extracted from inflorescences of row 8 of PB113+, PB121+ hybrid and GOA cultivar. Three different treatments that varied time and temperature were set. The physico-chemical characterization concerned the sugar samples from each pair. Samples of white and brown sugar from sugar cane, sold commercially in Côte d'Ivoire, were used as controls.   Place and Duration of Studies: Marc Delorme Station for Coconut Research at the National Centre for Agricultural Research, Côte d'Ivoire between January 2017 and March 2018. Methodology: The sap from the freshly collected coconut tree inflorescences was directly transformed into granulated sugar by thermal spraying (Okoma et al, 2019), without preservatives. Three treatments varying the time/temperature pair were tested. Thus, the processing consisted of: T1: boil 1 liter of sap for 45 minutes at a temperature varying from 60-120°C. T2: boil 1 liter of sap for 40 minutes at a temperature varying from 60-140°C. T3: boil 1 liter of sap for 35 minutes at a temperature varying from 60-160°C. The physico-chemical characterization concerned the coconut sugar samples from each treatment and covered the dry matter content (DMS), moisture (HUM), ashes content (ASH), hydrogen potential (pH), titratable acidity content (TAT), total and reducing sugar contents, fat content and crude fibers. We considered the white and brown sugar from sugar cane sold in the sample as control samples. Results: All the physico-chemical characteristics of the crystalline coconut and sugar cane sugars analyzed generated significant differences (p<0.5) between them and the controls. Regardless of the treatment, the controls white and brown cane sugar provide statistically identical DMS, greater than 99.45 g/100 g respectively. These levels are higher than those provided by the sugar of coconut cultivars. In addition, white (0.27 to 0.29) and brown (0.42 to 0.50) cane sugar contains less water than all coconut cultivars (0.76 to 1.70). Regardless of the treatments applied, crystalline coconut sugar contains ashes contents (ASH) that range from 1.45 to 2.85 and are statistically higher than the proportions found in brown sugar cane sugar (0.11 to 0.28). White sugar cane sugar does not contain ashes. The pH of white sugar and brown sugar (6.09 and 6.44) is significantly higher than that of coconut sugar (4.82 and 6.19). The titratable acid content of coconut sugar ranged from 1.25 to 2.19 compared to 0.94 to 1.99 in cane sugar. Total sugar contents (TST) represent 81.15 to 87.54% of the dry matter in coconut cultivars. This is lower than the TSTs for white sugar (99.01 to 99.04%) and brown sugar (95.6 to 95.73%) sugar cane. Crystal sugar in coconut cultivars contains statistically fewer reducing sugars (6.75 to 7.89%) than white sugar cane sugar (8.11 to 8.12%). Its red counterpart, with 6.14%, contains smaller amounts of reducing sugars. Conclusion: Sugars are the main constituents of the dry matter of the coconut and cane sugar crystals studied. However, the different heat treatments applied to the sap of coconut inflorescences significantly affected all the physico-chemical parameters of each sugar. The physico-chemical characteristics have statistically differentiated coconut sugar from sugar cane sugar. However, for a better valorization of crystalline coconut sugar in Côte d'Ivoire, additional studies to determine its carbohydrate, mineral, vitamin and energy content should be considered.