Extracting microcrystalline cellulose from banana fiber and determining conformity for use in bread and cake as a food additive

In this thesis, the acid hydrolysis step was optimized for the production of microcrystalline cellulose (MCC) suitable for use as a food additive from banana fiber, a local resource. For this purpose, it was determined that MCC produced from banana fiber (M-MCC) complies with the Turkish Food Codex (TGK). The characteristic properties of M-MCC were determined and compared with MCC from the Turkish market (T-MCC). In addition, the effect of MCC on the quality characteristics of cakes and breads was analyzed. In the optimization study for the acid hydrolysis method, optimization of acid concentration (0.5-2.5 M HCl), acid solution (ml)/material (g) ratio (10-30), temperature (60-100 ºC), and process time (40-180 min) parameters were carried out by considering yield, degree of polymerization (DP) and particle diameter less than 5 μm (%) values. In the optimization study, a response surface method, the central composite design was used to create the analysis modeling. The optimum conditions for acid hydrolysis were determined as adding 2.06 M HCl solution to the ground banana fiber at a ratio of 1/25 (banana fiber (g)/acid solution (ml)) and treating at 80 °C in a water bath for 75 min. By performing the analyses specified in TGK, it was determined that the M-MCC produced by the method obtained as a result of optimization had the appropriate properties in TGK. When the characteristic properties were examined, it was observed that the degree of polymerization (DP) of T-MCC and M-MCC were 390.90 and 197.30, respectively, and the scanning electron microscope images of the samples showed that the M-MCC sample had a more fibrous structure than T-MCC. It was observed that the crystallinity index (CrI) values were 76.28% and 74,39%, respectively, and the crystallinity value of M-MCC was lower. When Fourier transform infrared spectroscopy (FT-IR) spectra were examined, it was observed that the properties were similar. When the thermal behavior properties were examined, it was observed that cellulose decomposition in MCC samples started at 315 °C and continued until 400 °C, reaching the maximum weight loss rate at 355 °C. After determining the compliance of the produced MCC with the conditions specified in the regulation, the effect of its use as a fat replacement in the cakes on the quality characteristics and shelf life of the cake were examined. Firstly, the effects of the use of MCC as an oil replacement at the ratios of 15, 20, 25, 30, and 50 % to the fat content in the control cake were examined. In the shelf-life studies, it was decided to use M25 cake formulation for shelf-life studies. The difference between the cakes containing T-MCC and M-MCC produced using M25 cake formulation and the control cake sample was determined. In the studies conducted on bread, the quality characteristics of breads containing T-MCC at 0.5, 1, 2, and 4% ratios were investigated by comparing with the control bread without MCC. As a result of the study, an optimized hydrolysis method was determined to produce MCC, legally suitable for use as a food additive, using banana fiber, an agricultural waste. In addition, the effects of using MCC as an additive to the quality and shelf life of bread and cake were investigated. Using MCC in bread on shelf life, no significant effect was found. The use of MCC as an oil replacement in cakes did not have a significant adverse effect except for increasing the hardness of the cake and it was determined that it had a positive effect on storage by reducing the amount of oil and increasing the rate of indigestible fiber.