Thumbnail Image

Thesis

Browse

20161
Reset filters
Subject: Food Technology × Author: Rafiq, Aasima × Start date: 2014 × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Development and Assessment of Functional Properties of HTST Processed Pregelatinized Pasta
    (Punjab Agricultural University, 2016) Rafiq, Aasima; Sharma, Savita
    The present investigation was undertaken to explore the potentiality of twin screw extruder for development and assessment of functional properties of High Temperature Short Time processed pregelatinized pasta. Semolina and brown rice (singly or in combination with legume) and different multigrain blends were used for preparation of pregelatinized pasta. General factorial design was used for generating experimental runs for semolina and multigrain pasta. For brown rice and cereal-legume pasta response surface methodology was used for optimization of the extrusion processing conditions and regression analysis was carried out to fit mathematical models to the experimental data. Feed moisture (28-36%), barrel temperature (60-110°C), screw speed (100-200rpm), legume level (10-30%) and different multigrain blend composition were chosen as the independent variables while degree of starch gelatinization, cooking quality (minimum cooking time, water absorption, volume expansion and gruel solid loss), amylose leaching and swelling power were the product responses. Different raw materials were subjected to extrusion by co-rotating twin screw extruder at varying processing conditions as per the experimental design. Functional properties of HTST processed pregelatinized pasta were significantly affected by the processing conditions. Degree of starch gelatinization (DSG) by amylose-iodine method revealed that feed moisture and barrel temperature showed a positive correlation with degree of starch gelatinization whereas increased legume level depicted an inverse effect. Overall, higher screw speed and feed moisture exhibited dominant effect on the cooking quality of pregelatinized pasta (semolina, brown rice, legume supplemented and multigrain pasta). Luminosity, redness and yellowness increased with increasing feed moisture. Pasting properties revealed lower peak and final viscosity with increased barrel temperature. Firmness of cooked pasta elevated with an increase in the barrel temperature and feed moisture. The samples processed at higher feed moisture and lower barrel temperature depicted higher retention of total phenolics and flavonoid content. Increase in antioxidant activity of pasta was noticed at higher feed moisture and lower barrel temperature. Extrusion processing was found to improve the in vitro starch and protein digestibility of pregelatinized pasta prepared from various cereals (singly or in combination with legumes). Pregelatinized pasta undergo extensive gelatinization as inferred from differential scanning calorimetry. The scanning electron microscopy images displayed varying patterns indicating polymer leaching, starch degradation and void air cells in the pregelatinized pasta. Irrespective of raw material, dynamic viscoelasticity analysis of pasta revealed that storage modulus (G´) was found much higher than loss modulus (G´´) indicating more elastic behaviour. The pregelatinized pasta packed in High density polyethylene and stored at ambient storage conditions were found acceptable up to 5 months storage period. The pregelatinized pasta products prepared at optimized processing conditions viz. feed moisture (31-32% for semolina and brown rice pasta, 32-36% for legume supplemented pasta and 34% for multigrain pasta), barrel temperature (90°C) and screw speed (200rpm) exhibited most desirable functional, cooking, sensory characteristics and mass acceptability.