Hydro 2000mu

Sediment grain size was determined by laser diffraction after 1min sonication to separate particles, using a Malvern Hydro 2000 MU particle size analyser in conjunction with the Mastersizer 2000 software. Three replicate sediment samples from each site were pooled and homogenised. Approximately 1g of sediment was added to the particle size analyser and 3 independent size determinations were made. This was repeated 3 times using the same pooled sample to determine an overall average.

Juice particle size distribution was determined by applying the laser diffraction method and Mie theory, following the ISO13320 regulation [21 ], by using a particle size analyser (Malvern Instruments Ltd., Mastersizer 2000, Malvern, UK) equipped with a wet sample dispersion unit (Malvern Instruments Ltd., Hydro 2000 MU, Malvern, UK). Laser diffraction reports the volume of material of a given size, since the light energy reported by the detector system is proportional to the volume of material present. The Mie theory requires the information on both the sample and the dispersant optical property. For orange juice, the particle refraction and absorption were 1.52 and 0.1, respectively, and the water refraction index was 1.33. The sample was dispersed in distilled water and pumped through the optical cell under moderate stirring (1800 rpm) at 20 °C. The volume (%) against particle size (in µm) was obtained and the size distribution was characterised by the volume mean diameter (D (4,3)). The standard percentile d (0.1) or size of particle below which 10% of the sample lies and d (0.9) or size of particle below which 90% of the sample lies were also considered for juice characterisation.

A Malvern Mastersizer laser diffractometer (Mastersizer 2000 particle size analyzer, Malvern, Worcestershire, UK) equipped with a sample dispersion unit (Hydro 2000MU, Malvern, Worcestershire, UK) was used to determine the mean particle size of the latexes, 24 h after their preparation (25 °C). Samples were introduced into the sample dispersion unit and allowed to equilibrate before measurement, to ensure full dispersion. Dry powder mean particle size was determined by an automated dry powder dispersion unit (Scirocco 2000 Malvern, Worcestershire, UK). For the redispersion experiments, dry powder samples were re-dispersed in deionized water by ultrasonication for 1 min and then the mean particle size of the resulted suspension was measured in the same way as previously described.

The particle size of the manufactured liposomes was determined using a Zetasizer (Malvern Instruments Ltd., nano ZS, Malvern, UK). In the case of the kiwifruit juice fortified with the liposomes, the particle size was measured by a Mastersizer (Malvern Instruments Ltd., Hydro 2000 MU, Malvern, UK). The zeta potential of both liposomes and the kiwifruit juice containing liposomes was studied using a Zetasizer (Malvern Instruments Ltd., nano ZS, Malvern, UK). The samples that were analysed by the Zetasizer were diluted (1:16) in 0.25 M acetate buffer (pH 3.8), while in the case of the Mastersizer measurements, no dilution was required [3 (link)].