Process conditions affect starch structure and its interactions with proteins in rice pasta

Published Date

15 February 2013, Vol.92(2):1865–1872, doi:10.1016/j.carbpol.2012.11.047

Title 

Process conditions affect starch structure and its interactions with proteins in rice pasta

• Author 

• Alberto Barbiroli
• Francesco Bonomi
• Maria Cristina Casiraghi
• Stefania Iametti ^,
• Maria Ambrogina Pagani
• Alessandra Marti

• Department of Food, Environmental, and Nutrition Sciences, University of Milan, Italy

Received 3 August 2012. Revised 24 October 2012. Accepted 18 November 2012. Available online 26 November 2012.

Abstract

Structural changes of starch and proteins in rice pasta were investigated as a function of raw-materials and pasta-making conditions, and their impact on cooking behaviour and glycaemic index was assessed. Rice pasta was prepared from untreated or parboiled rice flour by conventional extrusion or by extrusion-cooking. Starch structure was studied by assessing starch accessibility to specific enzymes (α-amylase and pullulanase), and by evaluating the molecular properties of fragments from enzymatic action. Protein solubility in presence/absence of chaotropes and accessibility of protein cysteine thiols allowed to evaluate the intensity and nature of inter-protein interactions. Parboiling stiffens the protein network in rice flour and makes starch more accessible to hydrolysis. Pasta-making induced further changes in the starch structure, that were most evident in pasta made from untreated rice and were mainly related to the amylopectin fraction. Thus, the interplay among structural modifications on starch and/or proteins affects the features of products.

Highlights

► Novel processes to prepare rice pasta with satisfactory properties were compared. ► Cooking quality of rice pasta relate to structural features of starch and proteins. ► Amylopectin structure was most sensitive to treatments used for production of rice pasta. ► Parboiling affected rice protein reticulation to a lesser extent than extrusion-cooking. ► Process-related structural changes had an impact on the glycaemic index of rice pasta.

Abbreviations

• DTNB, 5,5-dithiobis(2-nitrobenzoate)
• DTT, dithiothreitol
• GI, glycaemic index
• M, protein markers
• P1, pasta made from native rice flour by extrusion-cooking
• P2, pasta made from parboiled rice flour by conventional extrusion
• P3, pasta made from parboiled rice flour by extrusion-cooking
• PRF, parboiled rice flour
• RF, untreated rice flour
• RS, resistant starch
• TS, total starch

Keywords

• Rice pasta
• Parboiling
• Extrusion-cooking
• Starch structure
• Enzymatic starch hydrolysis
• Protein structural rearrangements

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• DOCX (1.6M)

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• ⁎ 
  Corresponding author at: DeFENS, University of Milan, Via G. Celoria, 2, 20133 Milan, Italy. Fax: +39 0250316801.
  
  

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