Preserve Lipid Quality During Extended Storage

3 Tips to Protect Fats and Oils from Oxidation During Storage

Fats and oils – or lipids – are an essential energy-source in nearly every animal’s diet. However, lipids are highly variable not only in their physical and chemical properties, but also in their susceptibility to oxidation – a key source of decreased fat quality. 

Storage time, application of heat, exposure to moisture and the mixing of different lipid sources conspire against fats and oils, increasing their susceptibility to oxidation. Worse yet, once oxidation starts, it cannot be undone; so, when it comes to preserving lipid quality during storage, avoiding oxidation altogether is critical.

Current market dynamics have forced many producers to alter their diets, including switching fat sources and storing fats and oils for an extended duration.1 This means fats and oils may be at increased risk of oxidation. Therefore, it’s a good time to ask, “how is my fat looking?” and brush-up on tips to get the maximum nutritional value from your stored fats and oils this year.

Tip 1 – Monitor Lipids for Oxidation Markers

Knowing the quality of the components going into your livestock feed – new and old – is practical and important. This is especially true for expensive ingredients, like supplemental fats and oils, which are highly variable in nature and can easily lose their quality and nutritional value over time. 

Purchasing high-quality fat, preferably from one or two verified suppliers is highly recommended as a first step in an oxidation control program. But, it’s important to understand that common fat quality measures – like color, moisture, insolubles, unsaponifiables, free fatty acid content, etc. – do not necessarily characterize oxidation damage.2

The oxidation process results in specific primary and secondary degradation products – peroxides and secondary oxidative molecules – which are produced at different stages of oxidation. Analysis of these molecules provides producers with a snapshot of the current state of oxidation damage in their fats and oils. Producers should also consider evaluating the susceptibility of fats and oils to future oxidation – via oxidative stability index (OSI) methods – which can provide insights into the future risks of oxidation.

Tip 2 – Don’t Forget About the Influence of the Fat Tank

When it comes to fat quality, the condition of the fat tank is often overlooked. Sediments in fats and oils accumulate as “sludge” at the bottom of the fat tank. Over time, this sludge builds up, and a layer of residue coats the inside of the tank. These residues contain high amounts of free radicals which, once mixed with new fat, disperse and immediately promote oxidation of the new fat.

As the two examples below illustrate, a dirty fat tank is the enemy of stored fat quality. In the first study, corn oil stored for two months in a dirty tank had 20X higher peroxides and greater than 2X more secondary oxidatives compared to when received (Table 1).3 A second study (Table 2) showed the OSI of poultry fat dramatically decreased after storage in a dirty tank for two weeks.4 Keeping your fat tank clean is critical to oxidation control, especially if fats and oils will be stored for an extended period of time.

Table 1. Influence of time on the current status of oxidation of stored corn oil.

Storage Time

Peroxide Value (meq/kg)

Secondary Oxidatives (ppm)

Fresh

1.5

88

1 month

16.8

127

2 months

30.8

187



Table 2. Comparison of the oxidative stability index (OSI) of non-antioxidant treated poultry fat stored for two-weeks.

Sample Location

OSI (hours)

Delivery 1

Delivery 2

Truck

34.9

13.0

Tank

0.2

0.2

Tip 3 – Use Antioxidants to Protect Lipids from Oxidation

Antioxidants are molecules added to fats and oils ingredients to help reduce lipid oxidation. Antioxidants work either by sacrificing themselves to quench free radicals before fatty acids can be attacked or by chelating pro-oxidant metal ions and acting as oxygen scavengers.

When using an antioxidant, it’s important to remember that it cannot reverse oxidation that has already occurred. Additionally, the effectiveness of an antioxidant depends on multiple factors including the substrate, antioxidant dose, chemistry synergy and time and place of application. For example, research has shown that TBHQ and propyl gallate are more effective for vegetable oils; whereas, BHA and BHT are most effective when used in saturated animal fats.5,6

Summary

Ultimately, proper storage of fats – including monitoring quality and protecting fat with antioxidants – is critical for producers to maintain the nutritional value of supplemental fats and oils. Developing an oxidation control program is even more important if fats and oils are to be stored for an extended duration of time.

With more than 50 years of experience, Kemin has developed liquid antioxidant solutions that will help protect your lipids from oxidation, thereby maintaining their quality and nutritional value during storage. For more information on how liquid antioxidant systems – such as RENDOX® – can help protect your fats and oils from oxidation, visit kemin.com/RENDOX.

 

References

1Patience, J. and L. Greiner. (2020). Approaches to reducing feed intake and growth rate in market hogs during interruption of animal movement. Accessed July 20, 2020. https://www.ipic.iastate.edu/information/ReducingFeedIntakeGrowthRate.pdf
2Shurson, J. and B. Kerr. Fat, oxidation and the swine diet. National Hog Farmer, July 19, 2018.
3Kemin Customer Laboratory Services project, CLSFR-18-095.
4Kemin Customer Laboratory Services project, CLSFR-19-001.
5Budilarto, E.S. and Kamal-Eldin, A. 2015. The supramolecular chemistry of lipid oxidation and antioxidation in bulk oils. Eur. J. Lipid Sci. Technol., 117:1095-1137.
6Comparative antioxidant efficacy of the antioxidants BHA, BHT, MTBHQ and ethoxyquin, BB-03-00649.

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