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How processing could affect its nutritional and sensory quality. Notes - KAILA
( Fardet, 1998)
-pasta is an ideal grain product for diabetics due to the slow release of carbohydrates, minimalizing blood glucose peaks and levelled insulin release. Compared to other grain products such as rice, potatoes and white bread, pasta has a lower gastric emptying rate, due to the dense firm texture produced during the extrusion process. It is the compact structure, and surface area to mass ratio- not the ingredients, nature of the duram wheat, or forming/drying conditions that is responsible for the low glycemic index of pasta. Having a large particle size, there is less surface area for alpha-amylase to fully digest the pasta. Having a finely ground pasta would lead to a pasta with a glycemic index similar to white bread.
The cooking stage is also important in reglulating the glycemic index. Swelling must be limitied to maintains the protein network integrity, trapping the gelatinized granules which also limits alpha-amylase digestive activity. Overcooking can fully gelatinize the starch granules and increases susceptibility to alpha amylase, leading to increased blood glucose levels.

- Spaghetti tested by (fardet) was thicker than the lasagna. Thinner noodles cooked for the last time as thick noodles were penetrated by the cooking water to the centre resulting in a fully gelatinized granules.
Protein structure limits alpha amylase and therefore glucose spikes via
1) limited accessibility and porosity (density)
2) tortuosity of the protein matrix- lengthens the pathway of the enzyme
3) interactions of alpha amylase with the protein matrix
4) the structure of the starch in pasta
(Paradiso, 2005)
- Functional properties greatly depends on the protein content and gluten strength
- During mixing, modifying the thiol and disulphide groups improvoes dough properties beaqcaue of their impact on associate forces in gluten structure
- Vitamin C – can be added to improve kneading and as an antioxidant

o – DHA (dehydroascorbate) – increases the formation of intra or inter molecular disulphide bridges between cysteine residues in gluten.
o Some vitamin C naturally in wheat kernels however levels decrease during dehydration processes during storage and milling of kernals.
(Hallfrisch, 2000)
- Gel forming property of soluble fiber sources (oats, barely)= mechanism to reduce cholesterol and glucose/insulin response
- High viscosity delays gastric emptying and intestinal absorption
- amylose (long gluc. Chains) amylopection (branched glucose chains)

o Hydrolysing amylose= less glucose released
o – corn varies from 30-70% amylose, has higher glycemic index than white bread, therefore input important
o Rice has wide range of glycemic index
o Wheat and barley have same glucose response
o Boiled whole kernals and larger particles size (less grinding) = low glucose and insulin response
(Hemery, 2007)
- Most pasta made from refined endosperm – lose micronutrients, phytochemicals and fibre found in germ and bran
- Dry fractionation technology – remove and recover peripheral tissues to maintain some nutrients
(Cubadda, 2009)
- Minerals – calcium, copper, iron, magnesium, phosphorous , potassium, selenium, zinc

o Roller milling reduced content but pasta making didnt furthur alter concentrations
o Cooking increases calcium content, other elements unchanged or minimally decreased, potassium decreased 74%
o Pasta- good source of selenium, copper, magnesium, zinc
o Pasta making little effect on element concentrations in semolina
o Can enrich by adding calcium, iron and copper in the water during dough production
o Equipment may release iron and copper into product
o May have slightly higher levels of copper and zinc in spaghetti vs. Macaroni
o Cooking inc. Calcium content, due to calcium in water
o Potassium dec. 1/4th of dry pasta
(Granfeldt, 1990)
- Macaroni has higher glycemic index, but only significant after 180 min

o Lower product thickness, greater surface area
- High temp drying procedure does not effect glucose response
(Leward, 1994)
- In extruder barrel, Shear force during extrusion make protein long range alignment difficult but short range intermolecular forces should survive (charge distribution of proteins athermal)
- Pressure increases ionization of carboxylate and amino groups of protein
- Temp has little effect on ionization

o As pressure increases with extrusion, so does total protein charge. Little water so the charges with react with one another
o As protein charge increases, strenght of extrudate decreases, and ability to absorb water increases
o Extruder makes ideal conditions (high temp, moisture) for maillard reactions (amino group condensates wtih free aldehyde or ketone group = brown, insoluble pigments)
o Lysine has free amino groups – decreases up to 50% depending on severity of the processing. (lysine is the limiting amino acid or cereal grains) therefore decreasing lysine will reduce nutritive value)
o High temps can break heat liable bonds (eg. Disulphide bonds)
(Lewicki, 2006)

- Fast increase of hot air temperature (30-75C) favours maillard reaction.
- Mode of temp. Increase had no effect on the extent of nutritional damage caused by drying
(Kamman, 1981)
- In enriched pasta, riboflavin concentration not changed under normal and harsh conditions
- Thaimin unchanged under moderate temperatures but decrease under harsh temperatures and contribute to a shortened shelf life
(Borrelli, 1999)
- Pasta yellow – quality of semoline – natural carotenoid pigments, protein, as and lipoxygenase (LOX) activity, and processing conditions
- Processing – pigment losses (16.3% loss of beta carotene)
- -pH of dough activates LOX 2 and LOX 3 enzymes –pigment loss
- - LOX activity is main factor in colour loss
- Want semolina with low LOX activity (more important than beta carotene content)