Ebrahim. A. A. Alfaig 1, Kamal Suleiman Hassen 2, Awad Elhaj Mohammed 3.

Transcription

1 Journal of Science and Technology 12 (02) December 2011 ISSN X Sudan University of Science and Technology Evaluation of Sugar Beet Parameters During Storage Ebrahim. A. A. Alfaig 1, Kamal Suleiman Hassen 2, Awad Elhaj Mohammed Food Science and Technology department, College of Agricultural Studies, Sudan University of Science & Technology, P.O. Box 71 Khartoum North, Sudan. 2. Sugar Research Institute, University of Gezira, P.O Box 20, Wad Madani, Sudan. 3. Sugar Cane Research Center, Sudanese Sugar Company, Elguneid, Sudan. ABSTRACT: Storability of four sugar beet varieties was tested during the winter season of at Elguneid Sugar Cane Research Center. Sugar beet varieties used in this study were Juvena, Mashad, Valentina and Brigitta. The storage conditions were at room, outdoors and underground temperature. The chemical analysis for samples was carried out for the fresh varieties samples and stated as control where the rest of the samples were optioned according to the following schedule: 24 h, 48 h, 72 h, one week, two weeks and one month with average of three replicates for each test. For the fresh samples of Juvena, Mashad, Valentina and Brigitta the moisture content was 80.7%, 83.8%, 81.1% and 81.1%, respectively. Ash content was 0.560%, 0.562%, 0.651% and 0.650%, respectively. Protein content was 0.210%, 0.226%, 0.202% and 0.190%, respectively. The weight loss % for the tested varieties after 24 h storage ranged from 5.57% to 8.32% and 5.65% to 6.70% for room and outdoor samples respectively. The pulp % for fresh tested varieties ranged from. 2.99% to 3.89%. Purity % for fresh samples was 81.18, 78.59, and for Juvena, Mashad, Valentina and Brigitta respectively. Reducing sugars% were 0.066, , and for the fresh samples of Juvena, Mashad, Valentina and Brigitta, respectively. The obtained results showed no difference between varieties, while there were marked differences among the storage methods and periods. Underground storage scored the best results which were comparable with the control (fresh). KEYWORDS: Beta vulgaris, Weight loss, and pulp, purity. INTRODUCTION Sugar beet ( Beta vulgaris L.) is a vegetable which has a great economical importance for its high nutritive and industrial value (Scalon et al., 2000). It is a temperate climate crop which is grown successfully in virtually all areas of the world where winter is not harsh. Sugar beet is a useful crop for farmers, particularly when incorporated into a rotational scheme. About 60% of the world's sugar is supplied by the stem of sugar cane, while the other 1 40% comes from the roots of the sugar beet; sugar cane and sugar beet have long been considered as a main source of sugar of which every nation is vitally interested in having a continuous supply (Ali, 2004). Many trials of sugar beet cultivation were conducted in Sudan but many of these trials were sporadic and inconclusive. Recently, some comprehensive work was carried out including the adaptability of the varieties and beet cultivation, and this trial started before five seasons ago in different

2 locations in Sudan under the supervision of Sugar Cane Research Center under the umbrella of Sudanese Sugar Company, by testing tropicalized varieties and it was found that the tested varieties showed a good adaptability under the specific conditions of the experiments, where a tuber and sugar yield comparable to the world standards could be attained (Elhaj and Obeid, 2006). The economic success of sugar manufacture depends to a large extent on the quality of the sugar beet, so the storage and the delivery of the beet should be at optimum conditions. The greatest effect on the rate of change in post-harvested beet is exerted by temperature, which affects the respiration rate of the harvested beet, and it is reported that more sucrose was lost by storage decay than any disease (Bugbee, 1972). A sugar beet factory can only be operated efficiently if the quality of the beet received is suitable for processing, so good storage and effective delivery scheduling are therefore imperative to avoidance of sugar loss. The idea of this research is to narrow the gap between cultivation of sugar beet and processing. The cultivation of sugar beet in Sudan in the experimental level gave a high yield ( t/ha) compared with the international average (34.2t/ha) which indicates a high potentiality for sugar beet processing (ELkarouri and ELrayah, 2006). The main objective of this research is to investigate the storability of tropical indigenous sugar beet under Sudan conditions and to recommend the optimum storage method. MATERIALS AND METHODS The beet samples were selected and harvested randomly from the field of Elguneid Sugar Cane Research Center. The samples were collected according to the program of the analysis in which some samples were harvested and collected in the first day and kept under specific storage conditions according to the experiment design. The experiment was condncted using four indigenous varieties of sugar beet under the names Juvena, Mashad, Valentina and Brigitta at different storage conditions: room temperature, outdoor and ground storage, and specific tests were done during storage periods with three replications for each trial. The interval time between tests was selected to enable the determination of the short term effect and the long term effect of storage on the sugar beet samples. The results were obtained according to the following conditions: Control: This treatment showed the results of the fresh samples analysis. Room storage: In this trial the beet roots were stored at room temperature ranging from 22 to 34 C. Out-doors storage: In this experiment the sugar beet roots stored out-doors at temperature ranging from 29 to 39 C. Under-ground storage: In this case the sugar beet samples were allowed to grow and harvested according to the agreed schedule. First tests were carried out for the fresh sample of each variety to be as a baseline and then the tests for samples were started after 24 h, 48 h, 72 h, one week, two weeks and one month from the first day of storage. During the experimental period, the following tests were carried out: Weight loss: This test was carried out only at room and outdoor storage. The samples were randomly selected by taking three roots of different sizes from each variety, marked with numbers and then weighed and the results were recorded as fresh weight. The marked roots returned to the same conditions of storage and then, weighed according to the program, the weight loss of each sample was recorded, and then the mean of the loss percent of each three marked samples was calculated on the basis of the weight of the fresh samples. 2

3 Moisture content: This test was carried out according to the Payne (1968) oven drying method. Ash content: The method of ICUMSA (1994) was used to determine the ash content of the sample analyzed in this study. Protein content: Nitrogen content was determined according to the AOAC method (1984) Kjeldahl method. Determination of total soluble solids (T.S.S): According to The method of ICUMSA (1994) and by using Brixometer (Tate & Lyle Process Technology London England, BT 02036) the Brix % juice was measured and Brix% Beet was calculated as followes: Brix % Beet = Brix%juice x {2+ [0.01x moisture content]} {1- [0.01 x Brix %juice]} Determination of polarization (Pol.): The sucrose content was measured according to ICUMAS1994(cold digestion method) as follows: About ml of the juice extracted by the disintegrator (Jiffco) was put into a beaker and then clarified by using filter paper (Whatman No.1) after the addition of lead acetate for precipitation. Then the instrument tube was filled by the clarified juice and placed. RESULTS AND DISCUSSION Proximate analysis: Table 1 shows the proximate analysis of the tested varieties of sugar beet. For the fresh samples of Juvena, Mashad, Valentina and Brigitta the moisture content was 80.7%, 83.8%, 81.1% and 81.1%, respectively and these values were higher than those reported by Bohn (1998) which ranged from 73% to 76.5% as an average. The sucrose content for the fresh samples of Juvena, Mashad,Valentina and Brigitta was 13.24%, 10.93%, 12.38% and 12.56%, respectively, where Bashari (2007) reported sucrose content of 13.26% and 13.90% for Juvena and Valentina 3 inside the polarimeter champer and allowed to make digital reading. Then the Pol. of the extract (juice) was recorded. Calculations were make as follows. Purity % = pol. %juice x100 Brix %juice Pol. % Beet = Brix % Beet x purity % 100 Reducing sugars: The reducing sugars levels in the extracted juices (by Jiffco) were measured with the 3,5- dinitrosalicylic acid reagent, by using Sucroscan instrument according to the method found in the Manual of Sugar Color Analysis and Other Photometric Methods in Sugar Processing. Pulp content of beet: Pulp% of the beet was calculated according to the ICUMSA (1994) method for calculation of un-extractable content of beet by using the following formula: Pulp % = (moisture% beet + brix% beet). Statistical methods: The statistical design used for this experiment was the factorial randomize complete block design; where the results obtained were statistically analyzed by using the SPSS program (SPSS for Windows 10) and the variation between means measured at 0.5% probability level. varieties, respectively, and these are considered lower than that reported by Bohn (1998) which was 14% to 20% as an average for sucrose content. Ash content was 0.560%, 0.562%, 0.651% and 0.650%for the varieties Juvena, Mashad, Valentina and Brigitta respectively, where Bohn (1998) reported an average value of ash content of %. Protein content was 0.210%, 0.226%, 0.202% and 0.190% for Juvena, Mashad, Valentina and Brigitta, respectively where Bohn (1998) reported an average value of 0.4% - 0.7%.

4 Table 1: Sugar beet constituents: Variety Moisture % Component Ash % Protein % Sucrose % Juvena Mashad Valentina Brigitta Weight loss in sugar beet varieties: Table 2 shows the average of weight loss of the tested varieties. The loss after 24 hour ranged between 5.57 and 8.32% for room storage and about 5.65 to 6.70% for out-door storage. These results are comparable to those reported by Scalon et al., (2000) in which they stated that the weight loss was 6.19% after 24 hours at 25 C. Also Scalon et al., (2000) reported that the weight loss varies according to the size and shape of the exposed surface. The big beet tubers relatively lost more weight than smaller ones. Also the weight loss was markedly increased in all the storage methods, and the maximum weight loss was found at out doors storage after one month and it was about 69.34% for Brigitta compared with 58.84% for the same variety and storage period at room tempreture. Table 2: Weight loss in sugar beet varieties (%) Variety Treatments (storage) 24 hrs 48 hrs 72 hrs 1week 2weeks 1month Juvena Room Out doors Mashad Room Out doors Valentina Room Out doors Brigitta Room Out doors The pulp percent for fresh samples ranged from 2.99 to 3.89 (Table 3). These figures are comparable to those results of 3.05 and 3.2 reported by Bashari (2007) for the varieties Juvena and Valentina, respectively. Table 3: Pulp in sugar beet varieties (%) Variety Treatments Fresh (storage) samples 24 hrs 48 hrs 72 hrs 1 week 2 weeks 1 month Juvena control 2.99 Room out doors underground Mashad control 2.30 Room out doors underground Valentina control 3.89 Room out doors underground Brigitta control 3.14 Room out doors underground

5 The pulp% was significantly ( P 0.05) increased with increasing storage period especially for out doors and room storage while it was in the acceptable range for the under ground storage in all Purity of sugar beet varieties: The results tabulated in table 4 show the values of purity% during different storage periods. For the fresh samples the purity% was 81.18, 78.59, 82.32, and for the varieties Juvena, Mashad, Valentina and Brigitta, respectively. Bashari (2007) found that the purity% for the fresh samples of Juvena of Valentina was and 81.09, respectively. It was clear that there were no significant differences between varieties, while there was variation between treatments; with the storage periods. After one month, the pulp% was above 30% for the out doors and room storage compared with less than 8% for under ground storage. a relationship between control and underground samples, which considered as beet with acceptable quality, where there was no variation between room and outdoor storage, and this considered as beet with poor quality. The statistical analysis showed no significant variation between times, and this may be due to the accumulation of the poly-saccharides (e.g. dextran) during storage and this gives a false Pol. reading, which affects the purity%. Table 4: Purity of sugar beet varieties(%) Varieties Treatments (storage) Fresh samples 24 hrs 48 hrs 72 hrs 1 week 2 weeks 1 month Juvena Control Room out doors Underground Mashad Control Room out doors Underground Valentina Control Room out doors Underground Brigitta Control Room out doors Underground Reducing Sugars in sugar beet varieties: Table 5 shows the reducing sugars % for the varieties Juvena, Mashad, Valentina and Brigitta and it was , , and 0.005, respectively. Bashari (2007 ) reported reducing sugars of and for the varieties, Juvena and Valentina, respectively. It is clear that there was no significant differences between varieties, while differnces between treatments were significant. The underground storage resulted in beet with normal reducing sugar content, while the out-door and room storage reanlted in beet with high reducing sugars which may cause problems in processing. 5

6 Table 5: Reducing Sugars in sugar beet varieties (%) Varieties Treatments (storage) Fresh samples 1 week 2 weeks 1 month Juvena Control Room out doors Underground Mashad Control Room out doors Underground Valentina Control Room out doors Underground Brigitta Control Room out doors Underground CONCLUSIONS The under ground storage showed the best results, so the best schedule for harvesting and the control of the last irrigation date may be the best solution for extending the processing campaign of the sugar beet under Sudan conditions. This research work was done under the Gezira state conditions, which were considered warmer than the north Sudan climate, REFERENCES 1. Ali, A. M. A ( 2004). Study of the growth and fresh root yield of sugar beet (Beta vulgaris) in the semi-arid environment of northern Central Sudan; Journal of Agriculture Investment, 2: A.O.A.C. (1984). Association of Analytical Chemists. In: The Official Method of the Association of Official Analytical Chemists. 14 th Edition, published by Association of Official Analytical Chemists, Washington, DC 3. Bashari, M. O. (2007). Carbonation of Sugar Beet Juice in Purification Process, M.Sc. University of Gezira, Wad Medani, Sudan. 4. Bohn, K. (1998). Composition of Sugar Beet, Sugar Cane and Chemical Behavior. In : Poel, P. W. V; Schiweck, H.; Schwartz, T. (eds). Sugar Technology Beet and Cane Manufacture. Verlag Dr. Albert Bartens; KG-Berlin. 5. Bugbee, W. M. (1972). Sugar beet storage 6 especially in winter season. All the conducted studies for sugar beet in Sudan recommended to invest in sugar beet processing in north Sudan, so, good results were expected for beet storage in northern Sudan conditions or at least the beet roots will be less affected by short time storge after harvest. decay; Research Sugar Beet Extension Report, 3: Elhaj, A. and Obeid; A. (2006). Sugar Beet Production in Sudan: A Challenging endeavor. Proceedings of Workshop on Sugar Beet Productions in Sudan; Industrial Research and Advisory Center; Khartoum North; December Elkarouri, M. O. and Elrayah, A. (2006). Prospects of Sugar Beet Production in Sudan; Journal of Agricultural Investment. 4: ICUMSA (1994). ICUMSA Method Book. ICUMSA Publication Dept. Norwich. 9. Payne, J. H. (1968). Sugar Cane Factory Analytical Control. The Official Methods of the Hawaiian Sugar technologists; Elsevier Publishing Company; Amsterdam 10. Scalon, S. D. Q: Filho, H. S. Sanddre, T. A. Silva, E. F and Krewer, E. C. D. (2000) Quality Evaluation and Sugar Beet Post harvest Conservation Under Modified Atmosphere. Brazilian Archives of Biology and Technology 43: