Chapter-5 74 PET FOOD FORMULATIONS AND STABILITY

Transcription

1 Chapter-5 74 PET FOOD FORMULATIONS AND STABILITY

2 Chapter INTRODUCTION There are a number of important considerations in the formulations of pet food and proper nutrition of dogs. Any formulation development is a multi step process' as shown in Fig. 1. where ideas are converted into concepts which ultimately take the shape of product. The product that meets the quality requirements is marketed and finally reaches the end user. In its crude sense, product formulation development is the process of meeting the needs of end user expectations. k Need ^ w Ideas w Concept w Product w ^ Marketing w Customers Fig 1: The process of product formulation development The new product formulation development is an extremely complex process, which demands the need and role of equipments in process operations, ingredients quality and quantity, process conditions and particle size, etc.,. Formulated extruded pet food products are the result of the interaction of the extrusion process and various ingredients of the pet food formula. That means qualitative and quantitative selection of the raw materials, particle size distribution of these materials in the formulation are important factors in achieving desired product qualities and extruder performance. The introduction of extrusion technology (chapter-02 and 03) has allowed the formulators to put forward the innovative ideas with wide range of applications including shaped and texturized products. As" discussed by Harper^ and Rosen^, the extruder applications for various ingredients include different types of materials like, extruded snack products, dry cereals, texturized plant proteins, forming pastas and pet foods. With the help of extrusion technology, the antinutritinal and undesirable factors in soybean are inactivated

3 Chapter-5 76 (chapter-04) for pet food applications. With this background, the following point is focused for discussions on pet food formulations and its stability. I. The discussion about nutritional criteria of ingredients for product development. II. Formulations and manufacturing of pet food. III. Pet food stability studies with raw and extruded soybean IV. Effect of extrusion on nutrients. I. NUTRITIONAL CRITERIA OF INGREDIENTS FOR PRODUCT DEVELOPMENT. When the right quality ingredients are mixed in selective proportion, the desired end product can be achieved with expected and enhanced quality parameters. The enhanced quality effect of the ingredients would result in a better value added product. The nutritive feeding value of the ingredients can be improved by extrusion cooking which contributes to optimum utilization of nutrients in formulations. Since the anti-nutritive factors of soybean are inactivated by extrusion as discussed in chapter-04, the extruded soybean was included in pet food formulations. The studies were focused on selection of the quality ingredients based on the following nutrient profile for pet food formulations. A. Proteins: Protein is an essential component of dog diet, providing amino acids for the physiological states of maintenance, growth, lactation and gestation"*. The raw materials are selected from different sources for pet food manufacturing. Many of the plant and animal sources provide required ingredients to Pet food. Since dogs are carnivores, by-product meals, meat and poultry meals, and meat-and-bone meal are commonly used as proteinacious ingredients in pet food formulations. These sources are used as animal proteins. Quality of the animal protein sources can vary from batch to batch and hence quality of these materials was tested before utilization in pet food formulations.

4 Chapter-5 77 Most dry foods contain a large amount of cereal grain such as com gluten meal/soybean meal which are used to boost protein percentages without expensive animal source. Generally, these meals are produced by heat treatment and their production methods involve either over, moderate or under heating. However, as discussed in. chapter-04, the extrusion cooking inactivated the antinutritive factors and therefore the extruded soybean was used in pet food formulations after confirming the inactivation levels. B. Fat The Fat used in pet food come from different sources of plant and animals. In general, vegetable fat from soybean, flaxseed and sun flower and animal fat from chicken, fish and mutton are used in Pet food formulations. Fat is included in Pet food formulations as an energy supplement as well as palatability enhancer. However, during extrusion of Pet food and subsequent storage the fat is susceptible to oxidation resulting in poor palatability. The deterioration of lipids can be attributed to both hydrolytic and oxidative rancidity^'^. The factors affecting the rate of lipid oxidation can be linked to heating^ In addition to the ingredients the porous nature, ph and heating affect the quality of the pet food as they may cause them to be more susceptible to oxidation during storage. This oxidation gets accelerated if the free fatty acids released by soybean lipase present are in the sample. As discussed in chapter-04, the soybean lipase activity gets inactivated due to extrusion process and hence does not contribute to the production of free fatty acids. In addition to the soybean extrusion antioxidants were added and optimum pet food extrusion conditions were maintained during pet food extrusion. C. Carbohydrate Once considered filler by the pet food industry cereal and grain products now replace a considerable proportion of the meat that was used in the first commercial pet foods. The amount and type of carbohydrate in pet food determines the amount of nutrient value the animal actually gets. Dogs and cats can almost completely absorb carbohydrates from some grains such as wheat and rice. In 1995^ a pet food company 'Nature's Recipe' pulled

5 Chapter-5 78 thousands of tons of dog food off the shelf after consumers complained that their dogs were vomiting and losing their appetite. Nature's Recipe's loss amounted to USD 20 million. The problem was a fungus that produced vomitoxin (a mycotoxin) a toxic substance produced by mold. Ingredients that are most likely to be contaminated with mycotoxins are grains such as corn, cottonseed meal, peanut meal, wheat and fishmeal. To avoid contaminations in pet food maximum residual limits as per USFDA are tested in the ingredients used for pet food formulations D. Additives and Preservatives Many chemicals are added to commercial pet foods to improve the taste, stability, characteristics or appearance of the food. Additives provide no nutritional value. Additives include Emulsifiers to prevent water and fat from separating, Preservatives to retain freshness and appeal to the customers. Artificial colors and flavors to make the product more attractive to consumers and more palatable to their companion animals. Fats used in pet foods are preserved with either synthetic or natural preservatives. Synthetic preservatives include butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), propyl gallate, propylene glycol and ethoxyquin. Natural preservatives include Vitamin C (ascorbate), Vitamin E (mixed tocopherols), and oils of rosemary, clove or other spices. Synthetic preservatives such as BHA and ethoxyquin are used in the present study of pet food formulations.

6 Chapter THE PET FOOD FORMULATIONS AND MANUFACTURING PROCESS During formulations, product development and manufacturing, pet food is subjected to palatability studies (chapter-07). Most of the dry food is made with the extruder as explained in chapter- 3. Ingredients* which are used in pet food are almost all similar for wet, dry and semimoist foods, although the ratios of protein, fat and fiber may change. The main difference between the types of food is the water content. It is difficult to compare directly the label claims from different kinds of food unless it is converted and equated to "dry matter basis". Q A typical pet food formula consists of the following specifications and ingredients. A. Pet food Specifications: Table-01 : Maintenance diet specifications for adult dog Constituent Specification BIS AAFCO Moisture Crude protein Crude fat Crude fibre Table-02 Pet food specification for different growth stages^. Species and Growth Stage Recommended Protein Recommended Fat Puppy Adult dog Performance dog Racing sled dog Lactating dog 28 17

7 Chapter-5 80 B. Ingredients for pet food : i. Grain Byproducts ii. Animal products: iii. Plant products (other than cereal based) iv. Industrial byproducts V. Other ingredients Different pet food formulations were done using the various combinations of ingredients as per the details given in 2.2. In addition to the combinations of above ingredients, the raw and extruded soybean was also used in the pet food formulations as indicated in table-03. The pet food formula RS was done as per the BIS specifications indicated in table-01 to assess the effect of raw soybean on pet food palatability (chapter-07) and stability. The other pet food formulations ES-01 to ES 03 were done with extruded soybean as per the specifications indicated in table-02 to study the implications on nutritional, palatability and stability parameters of pet food after soybean extrusion. Ingredients such as extruded soybean, ground wheat, rice powder, rice bran, com gluten meal, vegetable fat, vitamin, mineral and salt mix were used for the test formula 'ES'. The control formula 'RS' was done with the raw soybean, ground wheat, rice powder, rice bran, poultry by product meal, com gluten meal, vegetable fat, vitamin, mineral and salt mix. Ground wheat and rice were incorporated as starch additives, rice bran as source of fibre, soybean, poultry byproduct meal and corn gluten meal as protein sources and fat as energy and for palatability. Mixing was done in a mixer separately for all the formulations by transferring all the relevant ingredients into the paddle mixer. o The formulated mix was extruded as pellets as discussed in chapter-03. During extmsion, similar process conditions were maintained for all pet food formulations containing raw soybean and extruded soybean. Though raw soybean was co-extruded with other ingredients, the inactivation will not be effective as the friction, pressure and temperature generated may not rupture the cells of soybean particles during extrusion due to interference from the other ingredients present in the pet food formula.

8 Chapter-5 81 Table-03: Pet food formulations SI. No. Quantity Ingredients RS ES-01 ES-02 ES Soybean seeds Extruded soybean Ground wheat Ground rice Rice bran Poultry by product meal Com gluten meal Fat Additives Vitamins, Minerals and salt mix III. PET FOOD STABILITY STUDIES: A. Stability protocol: Pet food with extruded Soybean 'E-Ol' and Pet food with raw soybean 'RS' were subjected to product stability studies"^. Stability studies were planned for determining the stability of the Pet foods kept at atmospheric conditions 25 to 35 C temperature and 55 to 65_RH and at accelerated conditions ie., 40 C + 1 C temperature and RH. Analysis was carried out for Peroxide value and acid value'' which was used as the criteria to find out the activity of lipase for determining the shelf life of the pet foods. B. Results: Stability studies of Pet food ES-01 resulted in Peroxide values of 4.9 meq kg~l after 365 days at atmospheric conditions, 3.96 meq kg~l after 90 days at accelerated conditions. Whereas pet food RS resulted in peroxide values of 37.5 and meq kg"l at same atmospheric and accelerated conditions respectively.

9 Chapter-5 82 TabIe-04: Peroxide and acid values for Pet food samples at atmospheric Conditions. No. of days Peroxide value meq/kg of the pet food FFA as oleic acid ES-01 RS ES-01 RS Table-05: Peroxide and acid values for Pet food samples at accelerated conditions No. of days Peroxide value meq/kg of the pet food FFA as oleic acid ES-01 RS ES-01 RS The free fatty acid values for Pet food ES-01 were in 1.91 and 1.7 at ambient (365 days) and accelerated conditions (90 days) respectively Whereas pet food RS resulted in free fatty acid values of 6.9 and 6.1 at same ambient and accelerated conditions respectively.

10 Chapter-5 83 C. Discussion From the Stability studies data for test ES-01 and RS samples over a period of time the increase in peroxide values are considerably reduced for Pet food test 'ES-Ol' samples compared to test 'RS' samples. The peroxide results for test 'ES-Ol' samples kept at atmospheric and accelerated conditions as per the table-04 and table-05, indicated that the values increased from 0.9 and l.lmeq kg"' to 3.96 and 4.9 meq kg"' respectively propounding almost to 4 times increase in peroxide levels. The results for test RS samples kept at accelerated and ambient conditions indicated that the peroxide levels increased from 1.01 and 0.8 meq kg"' to to meq kg" respectively resulting almost 35 to 40 times increase in peroxide value. The peroxide values of test 'ES-Ol' and 'RS' pointed out that there is almost 10 times increase in the peroxide levels for test 'RS' samples compared to test 'ES-Ol' samples emphasizing the advantages of extrusion. The free fatty acid content which was calculated as oleic acid showed that for test 'ES-Ol' samples which were kept at accelerated and ambient conditions, the free fatty acid content increased from 0.42 and 0.49 to 1.7 to 1.91 respectively resulting almost to four times increase in free fatty acid content. Where as, for the test 'RS' samples which were kept at accelerated and ambient conditions, the free fatty acid content increased from 0.69 and 0.72 to 6.10 to 6.90 respectively leading almost to nine times increase in free fatty acid content. Results also indicated that increase in free fatty acid content for sample 'ES-Ol' reduced by five times when compared to test 'RS' samples. Test sample ES-Ol was stable atleast for 365 days at ambient conditions and 90 days at accelerated conditions indicating relatively less oxidation of pet food samples produced using extruded soybean in the formulations. These observations as indicated by the data in the Table-2 where the peroxide level in test 'RS' for 60"^ day samples kept at atmospheric conditions are 4.1 meq kg"' which is comparatively equal to 365 days test 'ES-Ol' samples with the peroxide values of 4.9 meq kg". It was also noticed that peroxide values further increased after 90 days indicating the instability of test 'RS' sample due to presence of lipase in raw soybeans. This instability was not observed in test 'ES-Ol' samples, where extruded soybean was included in the pet food formulations. The marginal increase in free fatty acid and peroxide values may be attributed to auto oxidation. This consistency in stability may be

11 Chapter-5 84 due to inactivation of lipase during extrusion of steam-conditioned material. This inactivation (chapter-04) of lipase resulted in low free fatty acid content and hence decrease in peroxide value when extruded soybean was incorporated in pet food formulations. The sudden increase of peroxide and free fatty acid values clearly indicated that lipase is active in raw soyabean contributing to the production of free fatty acids, which further resulted in increase in peroxide value due to oxidation. With this examination, utilization of raw soybeans in pet food formulations is not ideal to picturize as the quality ingredient. These observations emphasize the importance of steam conditioning and extrusion of soybeans at optimum process conditions. These extrusion conditions aid the inactivation of antinutritional factors in soybean and thereby suggesting extruded soybean for pet food applications and finally for the pet food product stability. IV. EFFECT OF EXTRUSION ON NUTRIENTS: To study the effect of extrusion on nutrients, the studies were planned to determine the proximate nutrient values. The nutrient analysis of crude protein, crude fat, crude fibre, calcium and phosphorous was done for raw soybean samples, extruded soybean samples and extruded pet food. 4.1 Results: Table-03: Proximate value for soybean Parameter Before extrusion After extrusion Crude protein Crude fat Crude fibre ± 0.70 Calcium Phosphorous ± 0.01

12 Chapter-5 85 Table-4: Proximate analysis of Pet food with extruded soyabean (ES-01) during stability studies Parameter Initial Values Accelerated conditions Atmospheric conditions 60" day 90'" day 120'" day 365'May Variation Crude protein ±0.44 Crude fat ±0.59 Crude fibre ±0.30 Calcium ±0.30 Phosphorous ±0.10 The results as indicated in table-03 that the proximate nutrient analysis values of soybean showed maximum variation of for crude fibre and minimum variation of for phosphorous. The analysis variation for crude protein, crude fat and calcium are , and± 0.02 respectively. For pet food with extruded soybean, the proximate value variations indicated for crude protein, crude fat, crude fibre, and calcium and phosphorous are ±0.44, ±0.59, ±0.30, ± 0.30 and ±0.10 respectively. 4.2 DISCUSSION: Further more as indicated in table-3, proximate analysis values for the test ES-01 pet food samples specifies that extrusion of soybean between 120 C and 140 C temperatures does not hamper the important major chemical nutrients, but improves the nutritional value of soybean by inactivation of antinutritional factors. Heating, cooking, rendering, freezing, dehydrating, canning, extruding, pelleting and baking are so common in place that they are simply thought of as synonymous with food itself'^. He observed that processing of meat and by-products, which are used in pet food could greatly diminish their nutritional value but cooking/extrusion increases the digestibility of cereal grains. The data as indicated in table-3 and table -04 and digestibility studies (chapter-07) supported their observation that proximate nutrient analysis values are not affected by extrusion. Nutrient analysis after stability studies at atmospheric and accelerated conditions showed maximum variation of ±0.59 and minimum of ±0.10 for crude and phosphorous respectively.

13 Chapter CONCLUSION: As discussed in chapter-04, the high temperature and pressure destroys antinutritional factors and ruptures oil bearing cells in short duration thus prevents untoward effects and improves the quality and stability of the extruded soybean and soybean products These data on pet product stability, unchanged chemical nutrients after steam conditioning and extrusion indicates that extruded soybean is a viable ingredient for pet food formulations'^. In fact, extruded soybean is an economical nutrient source compared to animal proteins and soy protein hydrolysate which is an expensive ingredient. Since extruded soybean (extruded at C temperature) has got good quality protein and fat, it can be used for Pet food formulations in addition to other animal sources compared to Soy protein hydrolysate (concentrate) which is an expensive ingredient.

14 Chapter References: 1. Hrushikesh B, Agashe and Jain N.K., 2006, Pharmaceutical Product Development, First Edition 2. Harper J.M., Food Extrusion, Critical Reviews in Food Science and Nutrition, 1979,1 l: ,feb. 3. Rossen J.L., and R.C Miller., Food extrusion. Food Technology, 1973,27 (8) Fahey, G.C. Jr. and Hussein. H.S., The nutritional value of alternative raw materials used in pet foods. Proc. Pet food Forum 1997, Watt Publishing Cp., Mt Morris, IL, pp Camire, M.E., Camire, A., Krumhar, K. Chemical and nutritional changes in food during extrusion. CRC Crit.Rev.Food Sci. 1990, Nutr. 29, Bjorck, I., Asp, N,-G., The effects of extrusion cooking on nutritional value- a literature review. J. Food Eng. 1983, 2, Becker, Ross. "Is your dog's food safe?" Good Dog!, November/December BIS (Bureau of Indian Standards), Indian standard Specification for Dog feeds, IS , page 4-5, Appendix-A, Clause Drs. Foster & Smith, Inc. 2007, Protein Requirements for Good Nutrition, (AAFCO nutrient profile) Veterinary & Aquatic Services Department, 10. Kenneth A Connors, Gordon L. Amidon, Valentino J. Stextla, 1986, Chemical stability of pharmaceuticals, 2"'' edition, page AAFCO: Association of American Feed Control Officials Incorporated. Official Publication Atlanta: 12. Wysong, R. L. Rationale for Animal Nutrition. Midland: Inquiry Press, Morris, James G., and Quinton R. Rogers. "Assessment of the Nutritional Adequacy of Pet Foods Through the Life Cycle." Journal of Nutrition, : 2520S-2533S.