The April issue has a number of interesting articles on petfood and horse feeds. Concentrating on the petfood topics and having been involved in the industry for years it always amazing me the new and different approaches to petfood developments. I am still intrigued by the use of insect meal in petfoods let alone human foods. Cat foods evaluated based on their environmental impact is also interesting as petfoods are judged in so many ways then they used to be. Horse feed discussions review the nutritional needs and methods of feeding. The central theme is the nutritional benefits and advancements of the diets for the animals in an environmental manner.
Insect meal as reviewed has a low cost per ton produced when compared to the other proteins normally used in petfoods. Having never worked with this ingredient assumptions are made that it will preform well as long as the basic needs of the production equipment are met. What? Needs of the production equipment? Yes, machines are built to be used to make products and they have ranges of operation. Yes, flexibility is needed but you can’t make an expanded product if you don’t have enough carbohydrate in the formula. Typically, a minimum of 10 to 15 percent starch for a low expanded product and approx. 20 percent starch or more for a more expanded lighter density product. Fat in the formula was another one, gradual inputs created heavier densities to a point where too much fat and the kibble started to not look good or hold together. Typically 17 to 22 percent if your extruded design could handle it.
Over the years the equipment has been improved to have a wider operational working range. One was the preconditioning and possible extrusion as elevated moisture levels. Seeing a major method of selling insect meal is in slurry form is a benefit. With the modern processing methods using computers flow meters etc. the addition of insect meal into a production stream would appear to be easier than expected. Modern extrusion gear has excellent preconditioning where liquids and dry ingredient meet and mix. Depending on plant design this insect slurry should allow for easy in setting up a sanitary method of inclusion. It seems insect meal could possibly have a level of bacteria thus this ingredient should be handled much like a raw meat which is my initial opinion at least.
Environmental petfoods, seems the industry is interested in the real cost of goods in relation to the cost to the planet. As noted, the real cost of wet petfoods is above homemade and dry kibble when discussing the environmental impact dollars by a large margin. It is mentioned that the cost of factory production, packaging and transportation was not included. I would venture to say these costs would be close to a wash. Most of this centered around the use of meat in wet petfoods, meat being in the 75 percent moisture range thus special Stainless-Steel equipment, refrigeration and higher weights (elevated moisture levels) for shipping would justify this prediction. Also, with dry kibble production the volumes made per hour and the effective shipping methods in existence for grains etc. the dry kibble production cost has always been lower on a pound produced basis. More than likely cost reasons justify the huge tonnage sales of dry petfoods over wet in the market place.
An interesting view is there are extrusion machines that can handle extreme levels of meat. It is approaching 200 percent meat of the dry feed flow rate and it is pumped into the conditioning cylinder. To explain, if you were making 10 tonnes per hour dry feed rate then 20 tonnes of meat or other liquid products such as slurries of vegetables etc. would be pumped in. This kind of system uses thermal energy over electrical energy and appears to be an economical method of production based on less kW per ton versus steam inputs between the two styles of systems.
Having mentioned vegetables, it is not unusual in incorporate these ingredients in petfoods. Can be ground dry ingredients or slurries. The development of freeze-dried bits, which have quick rehydration properties, are now mixed in combinations or sold as petfoods on their own. When bring in the use of twin screw extruders the possibilities of make kibbles that look just like carrots, peas and other vegetables does exist due to their control possibilities.
All of the above discussed products as well as any extruded products are influenced by time, temperature, pressure, moisture, energy input and other parameters. When you think of the base items that can vary in an extrusion process, they are feed rate, water and steam inputs, kW from the main drive, screw speed and the mechanical set up and specifically the die. Change the feed rate and screw speed and you effect the pressure and the temperature developed mechanically. Die changes can do the same but if you increase or decrease the screw speed you change the pressure at the die. Water and steam addition have a big input on the cooking process. Steam adds some water but heating is the main desired point. Change the water and the viscosity of the extrudate changes and ability to develop heat from friction. Controlling these points have about 80 percent of the aspects covered to make a great product. When you get down to it the number of possible changes to be made when extruding is minimal. However, they can have big effects on the final product thus computer control to manage these parameters on a micro basis to a set point with low tolerance allows for production control of the product at the highest possible production capacity.