309 Are microbes and free fatty acids impacting pet food quality and shelf-life?

Abstract Pet food manufacturers strive to produce the highest quality products, understanding factors that impact the nutrient profile and palatability of rendered meals and fats is a critical piece of the ingredient quality puzzle. While AAFCO definitions exist for these rendered products, everything from production methods to seasonality can impact the final product quality. Raw material from an animal harvest facility will possess an inherent microbial load. Although these microbes are inactivated during the rendering process, the transit time between the harvest and rendering facilities provides time for microbial degradation of proteins and fats into biogenic amines and free fatty acids (FFAs). These compounds are heat stable, thus surviving the rendering process and remaining in the finish product. While most pet food manufacturers have a limit for incoming FFAs, demand for fats across various industries has resulted in specification adjustments from 3%, up to 5%, and sometimes 10%. In effort to better understand ingredient variability, an analysis of over 4,000 chicken fat samples submitted through Kemin’s Customer Laboratory Services between September 2021 through May 2023 was completed. Results showed FFAs ranging from 0.1 to 18.3 percent, with over 70% of samples with elevated FFAs (>5%) observed between June and September. This result highlights that summer heat promotes microbial growth and lipase activity in rendering raw material. For pet food manufacturers, understanding the impact of FFA’s and biogenic amines on palatability and shelf life plays an important role in valuing the quality of rendered ingredients. Studies have shown that limiting biogenic amines in a final pet diet or treat can improve palatability. Furthermore, multiple studies have shown a negative impact on palatability in cat diets when incorporating fats with FFA’s greater than 5%. In fact, when comparing diets utilizing 10% coating fat, cats favored the low FFA fat (0.5%) 65:35 compared to high FFA fat (10%). Additionally, shelf-life studies show that utilizing fat with 5% FFA compared to 0.5% FFA reduces the shelf life by 22 – 50%. In fact, diets utilizing fats low in FFA with no antioxidant had better shelf life than diets utilizing fats with 5% FFA and treated with antioxidant. This highlights the importance of raw material quality on palatability and shelf life. While preservatives can help achieve longer shelf-life goals, these ingredients cannot turn poor quality raw materials into high quality finished products. Implementing microbial controls prior to rendering can help limit negative attributes. Use of these strategies may be especially beneficial for preserving rendered material freshness during hot, summer months and for raw materials experiencing extended transit times between harvest and rendering facilities. For pet food manufacturers to maximize palatability and shelf life, raw materials should have limited biogenic amines and free fatty acids.