Effects of fiber content and extrusion conditions on quality of pasta

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Graduate School of Natural and Applied Sciences, Turkey

Approval Date: 2019

Thesis Language: English


Principal Supervisor (For Co-Supervisor Theses): Serpil Şahin

Co-Supervisor: İlkay Şensoy


Both characteristics of raw material and processing conditions play an important role in the final quality of pasta. Durum wheat semolina is the main ingredient for pasta production due to its yellow-amber color and strong gluten proteins. Pasta can be enriched with other cereals, pseudo-cereals, whole wheat flours or pure fibers to enhance the product nutritionally. However, partial substitution of durum wheat flour with these raw materials has an adverse effect on product quality. The aim of this study was to investigate the effects of the addition of 5% lemon fiber and extrusion conditions on quality of pasta. Samples were produced at two temperature sets in the extruder: 40 ºC, 40 ºC, 65 ºC, 45 ºC (die:55 ºC) which was called as low temperature (LT) and 65 ºC, 65 ºC, 85 ºC, 70 ºC (die:80 ºC) which was called as high temperature (HT). In this study, it was observed that both addition of lemon fiber and extrusion temperatures did not affect the cooking time, cooking loss and texture of products. A higher swelling index was observed when the extrusion temperature increased. Lemon fiber addition had no effect on swelling index at low temperature but it increased swelling index at high temperature. The water absorption index increased as extrusion temperature increased and with the addition of lemon fiber. It was observed that the rehydration rate increased as the extrusion temperature increased in the lemon fiber added pasta but not in the pasta without fiber. The rehydration rate also increased by adding lemon fiber. The addition of lemon fiber made the color of dried pasta darker and less yellow. The ratio of soluble and insoluble fiber in the pasta was not affected by extrusion temperature conditions. SEM images showed more disorganized and uneven structure in the pasta produced with lemon fiber, and more consolidated structure in the pasta produced at high temperature.