A solvent displacement method was used to prepare lutein nanodispersions. The effects of processing parameters (addition method, addition rate, stirring time and stirring speed) and emulsifiers with different stabilizing mechanisms (steric, electrostatic, electrosteric and combined electrostatic-steric) on the particle size and particle size distribution (PSD) of the nanodispersions were investigated. Among the processing parameters, only the addition method and stirring time had significant effects (p<0.05) on the particle size and PSD. For steric emulsifiers, Tween 20, 40, 60 and 80 were used to produce nanodispersions successfully with particle sizes below 100nm. Tween 80 (steric) was then chosen for further comparison against sodium dodecyl sulfate (SDS) (electrostatic), sodium caseinate (electrosteric) and SDS-Tween 80 (combined electrostatic-steric) emulsifiers. At the lowest emulsifier concentration of 0.1%, all the emulsifiers invariably produced stable nanodispersions with small particle sizes (72.88-142.85nm) and narrow PSDs (polydispersity index<0.40).
Postharvest, pea vine field residue (haulm) was steam-sterilised and then juiced; a chloroplast-rich fraction (CRF) was recovered from the juice by centrifugation. The stability of selected nutrients (β-carotene, lutein, and α-tocopherol) in the freeze-dried CRF material was measured over 84 days; the impact of temperature (-20 °C, 4 °C, 25 °C and 40 °C), light and air on nutrient stability was established. All three nutrients were stable at -20 °C and 4 °C in the presence or absence of air; this stability was lost at higher temperatures in the presence of air. The extent and rate of nutrient breakdown significantly increased when the CRF samples were exposed to light. β-Carotene appeared to be more susceptible to degradation than lutein and α-tocopherol at 40 °C in the presence of air, but when CRF was exposed to light all three nutrients measured were significantly broken down during storage at 25 °C or 40 °C, whether exposed to air or not.