In this work, a high shear mixer (HSM) is designed to produce a higher theoretical shear rate than conventional HSM in order to induce structure degradation of cassava starch granules. Using scanning electron microscopy and transmission electron microscopy, the processed cassava starch granule surface changes are identified without any major change in the granule shape. The carbohydrate component analysis and intrinsic viscosity suggest that the structural change is led by the removal of a relatively low-molecular-weight carbohydrate component from the granule. The changes in the crystalline and thermal properties are observed by the degradation process using a HSM. The process using a rotor speed of 15 000 rpm is found to significantly induce granule surface changes and carbohydrate removal. The decrease in granule crystallinity is correlated with an increase in the granule swelling power and solubility.
BACKGROUND Starch degradation is an important process that can increase starch utilization in some industrial applications. In many polysaccharide compounds, the addition of salt is an alternative method to enhance the structural degradation of starch by sonication. This study aimed to investigate the effect of sonication in aqueous NaCl solution on the structural degradation of cassava starch. RESULTS This method produces reducing sugar which its amount is relatively smaller than the amount of total dissolved solid product. The maximum total reducing sugar (TRS) was 0.365 ± 0.005 kg m–3 (or about 7.3 mg g–1) that resulted by S50 for 60 min reaction. The increase of sonication amplitude was in line with the increase of granule defect in SEM image. X‐ray diffraction (XRD) showed that the degradation process was characterized by rupturing of the amorphous region. CONCLUSION The structural alteration and the increase in NaCl weight suggest that this process may become a useful method for starch modification. © 2020 Society of Chemical Industry
Cassava starch is one of the biopolymers which can be degraded to many useful products such as reducing sugar, non-reducing sugar and modified starch. However, it has a solid granule structure that can inhibit its degradation process. High shear mixing (HSM) is a well-known method for dissolving biopolymers. Shear effect of HSM created by a narrow slit between rotor and stator which can be increased by the increase of rotational speed. By increasing its shear effect, HSM is able to cut the glycosidic bond of starch to produce reducing sugar. Therefore, this study aims to study the effect of high shear rate to granule structure and reducing sugar product. The HSM process was carried out on the suspension of cassava starch with a concentration of 1/20 (g/mL) for 15 min at various stirring speeds (5000-15000 RPM). Products produced from the process are separated between solid and liquid for analysis. Solid products were analyzed using Scanning Electron Microscopy (SEM), Particle Size Analysis (PSA), and Viscometer Ubbelohde. While liquid products were analyzed using UV-Vis Spectrophotometry with the DNS method. Based on the experimental results, HSM produced reducing sugar up to 0.1972 mg/mL. Granule breakage was also observed by SEM and increasing of the nanoscale granule.
Pati singkong memiliki komposisi utama (dalam berat kering) 23% amilosa dan 77% amilopektin yang tersusun atas monomer glukosa. Oleh karena itu, pati dapat dikonversi menjadi gula pereduksi yang dimanfaatkan sebagai bahan baku industri pangan maupun non pangan. Penelitian ini bertujuan untuk mempelajari pengaruh waktu proses sonikasi terhadap konsentrasi gula pereduksi yang dihasilkan. Proses sonikasi dilakukan terhadap suspensi pati 1/20 (w/v) pada kondisi operasi frekuensi 20 kHz, amplitudo 50% dan suhu 60 °C untuk berbagai waktu proses (15-120 menit) disertai pengadukan 250 rpm. Produk yang dihasilkan dari proses sonikasi dipisahkan antara solid dan liquid. Untuk produk solid dianalisis dengan menggunakan Scanning Electron Microscopy (SEM) dan X-Ray Diffraction (XRD). Sedangkan produk liquid dianalisis menggunakan Spektrofotometer UV-Vis dengan metode DNS. Berdasarkan hasil analisa DNS, dengan semakin lamanya waktu proses diperoleh peningkatan konsentrasi gula pereduksi dan konsentrasi maksimum sebesar 0,133 mg mL -1 . Hasil foto SEM menunjukkan bahwa sebagian granula pati rusak (pecah), dan dari hasil analisa XRD didapatkan penurunan derajat kristalinitas.The main composition of cassava starch is (in dry weight) 23% amylose and 77% amylopectin, which is composed of glucose monomers. Therefore, starch can be converted to reducing sugar that is used as a raw material for food and nonfood industries. This study aims to study several sonication processes on the concentration of reducing sugars produced. The sonication process was carried out on 1/20 (w / v) starch suspension at 20 kHz operating frequency, 50% amplitude, and 60 °C temperature for various time processes (15-120 minutes) for stirring 250 rpm. Products produced from the sonication process between solid and liquid. For solid products analyzed using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). While liquid products were analyzed using UV-Vis Spectrophotometer with DNS method. Based on the results of DNS analysis, the longer the process has obtained the increase in the concentration of reducing sugars and the maximum concentration of 0.133 mg mL -1 . SEM image results showed that some starch granules were damaged (broken), and from the results of XRD analysis, it was found that the degree of crystallinity was decreased. Kata kunci: Degradasi, gula pereduksi, pati singkong, pengadukan, sonikasi.
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