CHAPTER IV RESULT AND DISCUSSION
4.1 CHEMICAL CHARACTERISTIC OF SUKUH’S SWEET POTATO
STARCH
The moisture content, fat, protein, ash, carbohydrate, crude fiber, and amylose content of Sukuh sweet potato starch are shown in Table 6. Proximate analysis of Jago, Beauregard, and
Evangeline starch are shown in Table 6 as the comparison for each other. Table 6. Proximate analysis result of Beauregard, Evangeline, Jago, and Sukuh sweet potato starch
dry bases
Analyte Beauregard
Evangeline Jago
Sukuh
Moisture 3.97 ± 0.7
1.83 ± 0.4 13.73 16.45
Ash 0.08 ± 0.1
0.07 ± 0.1 0.23 0.20
Crude fat 0.23 ± 0.3
0.11 ± 0.1 0.44 0.65
Protein 0.17 ± 0.0
0.24 ± 0.0 0.56 0.69
Crude Fiber Carbohydrate
0.06 ± 0.1 95.49
0.00 ± 0.00 97.75
0.00 85.04
0.00 82.01
Amylose 23.60 ± 1.20
27.10 ± 0.30 25.83 ± 0.21
29.35 ± 0.67
Source: Futch, 2004; Devega, 2011
Sukuh variety is national superior variety of sweet potato with compact structure. It has 4-4.5 month of harvest age. Production of this variety reach 25-30 tonha. It has spherical and ellipse form
and has short stalk tuber. Sukuh has yellow skin color, white flesh and delicious taste. Sukuh has crude fiber content 0.85, protein content 1.62, total sugar content 4.56, starch content 31.16
RILET, 2008. Proximate analysis showed that Sukuh extracted starch has moisture content 16.45, ash content 0.20, crude fat content 0.65, protein content 0.69, carbohydrate
content 82.01, and crude fiber content 0. Sukuh is potential to be developed in starch and flour industry, include resistant starch industry, because it has high content of starch and flour yield
RILET, 2008. Decreasing of protein and fiber content showed purity of extracted resulted starch. Starch content of sweet potato depended on the variety as well as age during harvest. Sugar
content fell significantly when harvest was done beyond 90 days, but the amylose content was greatly affected by the time of harvest Antarlina and Kumalaningsih, 1990. Sukuh has harvest age 4-5
month 120 days, but it doesn’t influence the amylose content of the starch. The fibre content in sweet potato varies to a great extent depending on varietals variation and
age of the crop, where the fibre content increases with the maturity. Fibre content in starch derived from tuber extractions may vary to greater extent on the techniques and sieves, used for removal of the
fibrous material. Sweet potato flour containing 2-3 fibre had different compositions compared to the isolated starch having 0.1-0.15 fibre Moorthy, 2002.
Sukuh and Jago variety are the example of superior variety which is released by Research Institute for Legume and Tuber crops, Malang. Starch extraction of the sweet potato is obtained and it
has high purity. It can be shown that the amount of protein and dietary fiber in sweet potato tuber was higher than in extraction starch. High purity of starch is needed to make enzyme hydrolisis effectively.
18 Starch-protein interaction and formation of amylose-lipid complexes reduced yield of resistant starch.
Amylose-lipid complexes are enzyme-degradable,however retrogradation of amylose is dificcult to form crystalline structure and reduced yield of resistant starch Sajilata, 2006.
In 1987, at the Loisiana State University Agricultural Center LSU AgCenter Larry Ralston developed the Beaurgard, a new variety of high quality, high yield sweet potato and The Evangeline
sweet potato released by the LSU AgCenter in 2007 is a new variety of sweet potato developed by Dr Don LaBonte. Futch, 2009. The Beauregard sweet potato yielded a starch with 23.6 amylose,
while Evangeline, Jago, and Sukuh sweet potato starch contained 27.1, 25.83, and 29.35 amylose, respectively.Moorthy 2002 found that sweet potatoes have an amylose content around
20. Most of chemical content of two variety is similar with Sukuh sweet potato. The quality of chemical content sweet potato starch is affected mainly by the biological and environmental factors.
These factors include genotype, soil types, and climatic conditions, which are very different from one crop to another Katayama et al, 1999.
Differentiation result in proximate analysis appeared in the moisture content between Beauregard and Evangeline with Jago and Sukuh. Both of Beauregard and Evangeline have low
content of moisture content compared with Jago and Sukuh. Differentiation in method of starch extraction influence the differentiation of moisture content. In extraction of Beauregard and
Evangeline, pulp of sweet potato passed through a 150 µm sieve then it was centrifuge at 3000 g. The precipitate was removed and freeze dried Futch, 2009. Compared with method of Jago and Sukuh
starch extraction, pulp of sweet potato was not sieved through a 150 µm. Pulp of Jago and Sukuh sweet potato was sieved by adding distilled water with the ratio sweet potato : distilled water was 1 : 3
bv, then sieved by pore material. Starch was precipitated and washed by distilled water, then it was dried by oven. Water removal by freeze drier resulted lower moisture content on Beauregard and
Evangeline starch compared with Jago and Sukuh which were dried by dry oven.
4.2 PULLULANASE ENZYME ACTIVITY
Kategori