Texas A&M University - Articles and news items

Trans fats in foods and the commercial challenges

Issue 4 2013  •  28 August 2013  •  M. S. Alam Head of Fats and Oils Program, Food Protein R&D Center, Texas A&M University

Fats and oils are major sources of energy, providing nine kilocalories per gram compared to carbohydrates and proteins which provide only four kilocalories per gram and 3.8 kcal/g of energy, respectively. The two major sources of edible fats and oils are plants and animals. Plant sources or vegetable oils are found in abundance in seeds and fruits such as soybeans, cottonseeds, canola, sunflower, corn, peanuts, palm, palm kernels and coconut oil. The major animal fats include lards from pigs, tallow from cattle and sheep, milk fat from cows and fish oil.

The major component of most oils and fatty foods are triglycerides (95 – 98 per cent) represented as TAG whereas the fatty acids such as stearic acid (C18:0), oleic acid (C18:1), linoleic (C18:2), linolenic (C18:3), C16:0 (palm oil) and C12:0 (coconut oil) are the major building blocks of TAG. For example, in Figure 1, the TAG molecule is composed of a glycerol molecule. Attached to it are three different fatty acids, C16:0, C18:1 and C18:3. The terms mono unsaturated fatty acids (MUFA’s) and poly unsaturated fatty acids (PUFA’s) are used for fats containing one or more than one double bond. MUFA’s and PUFA’s are considered heart healthy fats if consumed in a balanced manner. Olive, soybean, canola, sunflower and cottonseed oil contain considerable amounts of MUFA’s and PUFA’s. Omega-3 fats are from the PUFA family and commonly found in most nuts (almond, cashew, walnut etc.) in fatty fishes and in plant oils such as flaxseed oil. Consuming omega-3 fats protects the consumer from heart disease and decreases the risk of many lifethreatening diseases such as diabetes and cancer.

Extrusion of rice analogue

Issue 6 2012  •  11 January 2013  •  Mian N Riaz, Head of Extrusion Technology Program, Food Protein R&D Center, Texas A&M University

Today, rice is one of the most important food crops in developing countries and it is considered staple food in many parts of the world. Rice is also becoming much more important in the United States, Europe, Asia and Middle East. However, concerns have been raised because it is high in starch and low in other essential nutrients. Another issue of concern is the breakage of rice kernels in the milling process, and these broken kernels are not generally accepted by consumers. Extrusion technology, which can be used to produce fortified rice, or rice analogues, can present a solution to both these problems, since desired nutrients / micronutrients can be incorporated in appropriate quantities in the rice mainly incorporating these nutrients in rice flour as the base material.

Rice is one of the leading food crops and sustains two-third of the world’s population, providing 20 per cent of the world’s dietary energy supply. Despite being a primary food, rice is low in protein and high in starch. The low protein levels in rice cause deficiencies of protein and some essential amino acids in people who take it as their primary diet. For example, lysine, which is responsible for proper growth of the human body, is the essential amino acid found in the lowest quantity in rice.

Extrusion of precooked pasta

Issue 2 2012  •  1 May 2012  •  Mian N. Riaz, Head Extrusion Technology Program, Food Protein R&D Center, Texas A&M University and Brian Plattner, Process Engineering Manager, Wenger Manufacturing Co

Pasta is a common source of carbohydrates in our diet today. Production and consumption of pasta products vary depending on the region of the world and culinary traditions within a society. Italy ranks as the highest consumer of pasta in the world at nearly 26 kilograms per capita, which is nearly double its next closest competitor, Venezuela1.

Most pasta products on the market, outside of instant noodles, are made from durum wheat semolina, and are processed via low temp – erature extrusion (less than 50°C)2. After extrusion and drying, these traditional pasta products have very low starch gelatinisation levels (less than 50 per cent) and must be cooked before serving. These products can also be treated to produce precooked pasta. This is accomplished after the conventional extrusion press process by a cooking stage in which the formed pasta is subjected to a steam or water bath followed by drying.

Another way to make a fully cooked pasta product without additional treatment is with extrusion cooking3. Typically, a twin screw extruder is used to wet the dough and cook and extrude it under high pressures and temperatures ranging from 90 to 110°C. This results in pasta products that can be rehydrated in three to eight minutes and they resemble the texture of those products made via a conventional process.

Extrusion of cereals

Issue 4 2010  •  26 August 2010  •  Mian N. Riaz, Head of Extrusion Technology Program, Texas A&M University

The world cereal yield was 2,219 million tons in 2009, according to the United Nations Food and Agriculture Organisation1. Cereal grains are grown all over the world and provide more food energy than any other type of crop, they are therefore staple crops. Cereals can be consumed in their natural form as whole grain and they are a rich source of vitamins, minerals, carbohydrates, fats, oils and protein. However, some cereals are processed using different methods where bran and germ are removed; the remaining endocarp is mostly carbohydrate and lacks the majority of the other nutrients.

In some developing nations, grain is in the form of rice, wheat, or maize (in American termin – ology: corn), which constitutes a majority of daily sustenance. In developed nations, cereal consumption is moderate and varied but still substantial. Cereals are processed using different methods to develop several cereal products that are consumed on a daily basis. One of the most commonly used processing methods for cereal is extrusion. This technology is used to develop breakfast cereal, extruded snacks, cereal based ingredients and several other cereals based on extruded food products.


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