Pasta Production NUFS 283 Food Engineering Group 3

Pasta Production NUFS 283: Food Engineering Group 3

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Introduction l Pasta is popular because it… Is nutritious l Is convenient to buy and prepare l Has a long shelf life l

Inputs: Ingredients l Semolina made from durum wheat l Water l Salt

Inputs: Ingredients l Optional: Eggs l Spinach, tomato puree, chilli, mushrooms for flavour l l Substitutes: Rice, corn, spelt, kamut for semolina flour l Whole grain, non-grain, or soy-bean flour for semolina to make it more nutritious l

Selection of Semolina l Semolina preferential to other flours for its Particle size l High protein content of 13 -14% dwb l Makes a less sticky dough during processing for easier extrusion l

Combining ingredients l Three steps involve Mixing l Processing l Extruding l

Combining ingredients: Pre-mixing l Ingredients flows into mixer is regulated by a volumetric or gravimetric doser l 0. 180 mm mesh sieve sifts the flour to aquire a homogeneous dough l The flour and water is sent through a high pressure pre-mixer to hydrate the mixture

Combining ingredients: Mixing l Bubbles are removed by a conventional dual shaft mixer to prevent a weak and pale pasta from forming l Warm water (45 -60°C) is added to bring the moisture content of the dough to 28 -32% l Spaghetti requires 16 -18 minutes in the mixing chamber

Mixing Calculation l Must consider energy balance of inputs in order to achieve desired properties: ∑Mi ⋅Δhi =Mflour ⋅Δhw +M⋅Em − Qj ∆hw = 15. 1 k. Jj/kg

Combining ingredients: Extrusion l Gluten matrix develops, assuming dough was sufficiently hydrated

Extrusion l An extruder ____ the dough. Convey l Compacts l Kneads l Relaxes l Extrudes l

Extrusion l Hydrated semolina mixture drops directly onto the extrusion screw l Screw brings mixture to extrusion barrel, where it is compacted l Pressure increase from to 2 MPa to form a compact dough l Screw continues to move dough along to extension plate

Extrusion: Challenges yet l Difficult to form uniformly kneaded dough l l Solution: apply a kneading plate Friction between the walls, barrel, and screw increases the temperature of dough Tremove = (TFrictional + TExtrusion screw)°C – 45°C (Specific Mechanical Energy) SME = Cp = 1. 44 + 2. 74 Xw l Ideal temperature: 45 - 50°C l l 50°C impedes gluten matrix formation Too cool will yield a dough with undesirable viscosity

Extrusion l Long pasta, like spaghetti are allowed a brief rest before entering the die in the extension tube l The pasta will be fully developed by the time taken to reach the end of the extension tube

Extrusion Die ? l Shape of insert determines shape of pasta l l l Circular for spaghetti Inserts are coated with Teflon to decrease friction and increase rate of extrustion l Also prevents pasta from absorbing water while being cooked Extruder output = drag flow - pressure flow - leakage flow

Extrusion Long pastas are left to stand on a spreader which cuts them into uniform lengths l Trims result from uneven flow out from the die l l l Are collected and brought back to mixer via trim return system Pastas are then attached to sticks are transfer to dryer

Drying l Purpose: to reduce moisture content to 12% to extend shelf life l Limits bacterial growth l To determine the amount of water to be evaporated: MCwb % =

Drying l Four factors involved: Humidity l Temperature l Time exposure to heat l Air flow l l Air flow and time exposure affects humidity and temperature

Drying: Air flow l Direct contact between air and the pasta enables the most efficient method of drying due to the greater surface area

Drying: Humidity l Wet hot air (40 -70% w/w) l Prevent product from cracking at high temperatures

Drying: Exposure Time l High temperatures requires shorter exposure time l Rapid drying may form cracks in the dough and result in a brittle the final product l Low temperatures requires longer exposure time l Moulds development, especially on the inner parts

Drying: Temperature l Ranges from 32 -110°C l Spaghetti: l Needs to be regulated because Too high = damage product and destroy nutrients l Too low = expensive and inefficient l

Drying: Temperature Regulations l Short pastas are regulated by: l Being on a shaking pre-dryer to decrease time exposure to high temperature in drier l Long pastas are regulated by: Pre-dried with blast of air for 30 -60 minutes l Dried at 55 -82°C l Cooled in a heat exchanger by indirect water contact at 28 -32°C for 1. 5 hours l

Improper cooling? l Damage the packaging l Contaminated product l Brittle product

Nutritional and Sensory Quality l Nutritious Carbohydrates l Protein l Vitamin B l Iron l Folic acid l Not fattening itself l

Nutritional and Sensory Quality l Ideal food for diabetics l l Slow digestion Maintains steady glucose levels Gradual insulin release Because of the limited surface area for alphaamylase l l l Tight protein structure Limited porosity With cooking, swelling of pasta restricted by tight gluten matrix and oligosacharrides

Nutritional and Sensory Quality l Yellowness of pasta determine by Adding eggs l Adding beta-carotene (most times) l l Beta-carotene (vitamin A precursor) Prevents many diseases l Immune function l Vision l l Processing makes this more bioavailable

Nutritional and Sensory Quality l Cooking should not exceed >50 C Damage gluten matrix l Loss of lysine, vitamins, furosine l l Mixing and extruding under pressure l Decrease beta-carotene oxidation l Water increase calcium and copper slightly