Food Technology Information Center

Hermetic and modified atmosphere storage of shelled peanuts to prevent free fatty acid and aflatoxin formation.

Hagit Navarro,, Shlomo Navarro, Simcha Finkelman* Food Technology International Consultancy Ltd., Israel

* Corresponding author e-mail: fticinfo@gmail.com

Abstract: The development of free fatty acids (FFA), molds and aflatoxins formation was studied on peanuts with 7.0% and 8.0% moisture contents stored under hermetically sealed conditions or in an atmosphere of 99% carbon dioxide and in comparison to aerated storage at 30 ± 1°C for 3 months. The laboratory trials were carried out using 0.95l capacity mason jars containing clean peanuts or peanuts with 3% broken peanuts at the two moisture content levels. In addition, semi commercial trials were carried out using 20kg of sound peanuts stored in hermetic SGBIIZ (GrainPro Inc.) bags at the same two moisture contents and the controls containing 7kg of sound peanuts were stored in ordinary PE bags. Each trial was replicated 3 times. Moisture content, FFA (% of oleic acid), Colony Forming Units (CFU) of molds and B1, B2 G1 and G2 aflatoxins were checked on the outset of storage and after 3 months. Respiration rates based on the oxygen consumption of the microflora and the peanuts and the carbon dioxide evolved were monitored periodically. The fastest respiration rate (oxygen depletion) obtained in the jars was with 8% moisture content peanuts containing 3% broken nuts after 18 days while at 7% moisture content sound peanuts reduced its oxygen concentration to a level of 1% after 84 days. In the SGBIIZ hermetic bags, at the 8% moisture content, the oxygen was depleted after 44 days compared to the laboratory tests in jars which the lowest oxygen was obtained after 28 days. In all trials, aflatoxins level was below the threshold limit ≤ 0.3ƒֺg/kg). In peanuts stored under hermetic conditions the CFU formation ≥ 1.3*10⁴) and FFA rise (≥ 0.57) were suppressed compared to the aerated samples. Best quality preservation for peanut storage with low CFU (≤ 9.7*10¹) and low FFA (≤ 0.77) was obtained under controlled atmosphere of 99% carbon dioxide for both moisture contents in peanuts containing 3% broken.

Key words: peanut storage, hermetic, carbon dioxide atmosphere, moisture content, shelled peanuts, FFA, aflatoxins, CFU, oxygen depleted atmosphere.

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