AQUAFEED EXTRUSION
FEATURE
Extrusion PART 2 Extrusion process and technologies:
E
Application in raw materials and feed production
xtruders can be visualised as a high temperature short time (HTST) device that can transform a variety of raw ingredients into intermediate and finished products. Extrusion technology provides several different advantages over traditional methods for feed processing. While many processing technologies result in an agglomerated feed, only a few have sufficient energy inputs to ensure feed safety. Feed safety is a major factor in choosing extrusion-based methods over traditional pelleting methods. Extrusion is a hydro-thermal process where the critical process parameters of retention time, moisture, and thermal and mechanical energy inputs can be varied over a wide range. The feed industry has considered a provision to mandate that all feeds are pasteurised and some form of extrusion will likely be implemented as the processing method of choice. Extrusion is a highly versatile operation that can be applied to a variety of feed processes. Extruders can be used to cook, form, mix, texturise and shape feed products under conditions that favor quality retention, high productivity and low cost. There are several ingredients that need some kind of processing to make it more digestible and palatable to use as feed ingredients. There are several agriculture by-products that can be processed into valueadded ingredients for feed application. Therefore, adding one extruder to a feed milling operation can add value to the ingredients and by products. At the same time, a feed miller can reduce the effects of mold, fungus, microorganisms and other anti-nutritional factors in these ingredients. The Philippines is producing an annual compound feed of about 13-15 MMT, about 40-45 percent are swine feeds, 20 percent layers, 20-25 percent broilers, three to five percent Aqua, and the rest are specialty diets such as pet foods, fighting cocks, etc. In 2016, the Philippines imported 2.3MMT of Soybean meal, about 82-83 percent from the United States, with the rest coming from Argentina. The whole soybeans import was around 80,000MT (FY2016). The import of soybean is growing and already has reached 135,000MT as of May 2017 (October 1, 2016- May 31, 2017). The production of full fat soybean meal in the last two years has increased more than double due to the
As presented by Dr Mian N. Riaz, Ph.D, Head - Extrusion Technology Program Graduate Faculty, Nutrition and Food Science Dept., Texas A&M University at the IndoLivestock “Feed Extrusion at the Philippine Livestock exhibition and conference� in Manila on May 25, 2017.
additional extrusion plants being installed in 2015-2016. The increased use of full fat soybean meal is largely driven by the high price of coconut oil which was the most common vegetable oil used to increase the level energy in swine and poultry diets in the Philippines. The United Soybean Export Council (USSEC) is very aggressive in promoting the production and use of FFSBM made from US soybeans.
Quality control in full-fat soybean meal processing
Full fat soybeans are thermally processed to destroy antinutritional factors and to increase oil availability while preserving the nutritional quality of the protein. The major anti-nutritional factor of concern in raw soybeans is a trypsin inhibitor. Inadequate heating fails to completely destroy the anti-nutritional factors, which may have a detrimental impact on animal performance. Excessive heating reduces the availability of lysine (via the Maillard reaction) and possibly, to a lesser extent, other amino acids. Laboratory tests are thus needed to determine whether samples of soybean meal have received adequate, but not excessive, heat treatment following oil extraction. Of tests commonly used, the evaluation of urease activity (UA) is the easiest to perform, and is especially useful in detecting under processed soybean meal. It is less reliable for detecting over processed meal. The protein solubility (PS) test is the most commonly used assay to detect over processed soybean meal, although very high values are indicative of under processed meal. The protein dispersibility index (PDI) is also used primarily to detect over processed or adequately processed soybean meal. Extrusion is a continuous process and has obvious advantages over simple batch cooking processes like boiling or autoclaving. It is also quicker than boiling since the beans have to be kept at boiling point for about 30 min to achieve reasonable levels of inhibitor destruction. The main variables associated with product quality and process efficiency as far as soybean processing is concerned are time, temperature, moisture content and the degree of physical damage needed to render the oil content more digestible. Extrusion is a readily controllable process where temperature, time (to some extent), moisture content and the degree of physical damage can all be manipulated. The net result of this is that a very high quality product can be produced when the extrusion process is properly handled.
24 | August 2017 - International Aquafeed