Supplementation of spinach powder into military rations is of interest to the Army because of lutein’s antioxidant activity in preventing light damage to the retina and enhancing photo-stress recovery. However, retained efficacy after long-term storage [3 years at 80oF; military required shelf life] is unknown. The stability of lutein was assessed in three model systems, a macronutrient balanced bar [20g] and a bread roll [60g] at two pH levels [3.8 and 5.8] and an energy gel [60g] at pH 3.8. 400mg of spinach powder (containing 104ug of lutein) was incorporated into each sample. Accelerated storage studies were conducted to assess stability @120oF for 4 weeks and 100oF for 6 months. Extraction and analytical quantification of lutein was conducted to determine losses due to storage. Analytical procedures were performed under yellow lights and an internal standard (trans-β-apo-cartenal) was used. Two extraction methods were developed. For bars and breads, lutein was extracted from samples using methanol. A second extraction method which used a two-step solvent extraction with methanol then diethyl ether was developed for gels because the product contained ~6% canola oil. Lutein was quantified using HPLC with UV/Vis detection @450nm. All 0 time samples were found to contain expected concentrations of 104 +/-10.4ug. No decreases in lutein were measured in the low pH bar after 4 weeks, and only 15% after 6 months. In comparison, the high pH bar lost &gt;40% in both storage conditions. In bread rolls, a decrease of 25% was seen in high pH, and 70% for low pH samples after both storage studies. The low pH gel had a 42% loss at 4 weeks and 85% reduction at 6 months. In future studies, a prototype bar will be developed specifically for incorporation of spinach powder guided by sensory attributes and stability tests.

Assessing the stability of lutein in model food systems supplemented with spinach powder

254th National Meeting (2017)

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