Aaron S.L. Lim

Beta-Carotene Stability in Extruded Snacks Produced Using Interface Engineered Emulsions

The objectives of the present study were to produce snack-type extrudates and to investigate their ability to encapsulate and protect β-carotene (0.05% w/w in sunflower oil) using single layer and layer-by-layer emulsions as an ingredient. The dry feed composed of wheat flour (60% w/w dry solids), maltodextrin (DE 23-27, 20% w/w dry solids), and lactose (20% w/w dry solids). The extrudates (0.6 aw) were ground and sealed in vials under vacuum, placed in vacuum-sealed plastic pouches, and stored at 20, 40, and 60°C. Analysis of the beta-carotene content during storage was carried out using HPLC with a C30 column and diode array detector. The results showed rapid loss of β-carotene during the first six days at all temperatures. Further losses of β-carotene at 20 and 40°C occurred gradually leveling off at 27 days. It was noted that the percentage of retention of β-carotene was generally higher in layer-by-layer extrudates with layer-by-layer upon storage for 27 days. It can be concluded that the layer-by-layer emulsion may enhance protection of bio-sensitive compounds in glassy membranes.

Stability of flocculated particles in concentrated and high hydrophilic solid layer-by-layer (LBL) emulsions formed using whey proteins and gum Arabic

The objective of the present study was to investigate flocculation in layer-by-layer (LBL) emulsion systems with high total solids content and deflocculation at various pH conditions, and the effects of whey protein isolate (WPI) concentration and total solids content on the stability of LBL emulsions. WPI (1.96% (1WPI) or 10.71% (10WPI), w/w in water) was prepared in water and high-pressure homogenized with sunflower oil (10%, w/w, of total emulsion). Gum Arabic (0.15%, w/w, in total emulsion) was added to assemble electrostatically on WPI at oil particle interfaces at pH3.5 using aqueous citric acid (10% w/w) forming LBL emulsion. The ζ-potential measurements showed charge reversal upon addition of gum Arabic solution into single layer (SL) emulsion confirming the formation of LBL interface. Trehalose:maltodextrin mixture (1:1, w/w, total emulsion, 28.57% (28) or 57.14% (57), w/w, in water) was used in the continuous phase. The high total solids content of the system results in depletion flocculation of the particles leading to bridging flocculation without coalescence as deflocculation into individual particles occurred with increasing pH from pH3.5 to pH6.5 in 10WPI systems. Deflocculation was evident in 10WPI-28 and 10WPI-57 as found from a decreased ζ-average diameter and visually under microscope. Coalescence was observed in 1WPI systems. Viscosity of the systems was significantly (P<0.05) increased with higher total solids content. Accelerated destabilization test showed that systems at higher WPI and total solids contents exhibited the highest stability against creaming. Deflocculation in LBL systems can be controlled by pH while high solids in the aqueous phase provide stability against creaming.

Benthic foraminifera in a deep-sea high-energy environment: the Moira Mounds (Porcupine Seabight, SW of Ireland)

Cold-water coral ecosystems represent unique and exceptionally diverse environments in the deep-sea. They are well developed along the Irish margin, varying broadly in shape and size. The Moira Mounds, numerous small-sized mounds, are nestled in the Belgica Mound Province (Porcupine Seabight, North-East Atlantic). The investigation of living (Rose Bengal stained) and dead benthic foraminiferal assemblages from these mounds allowed to describe their distribution patterns and to evaluate their response to environmental variability. Quantitative data was statistically treated to define groups of species/genera associated to specific habitats. The Moira Mounds differ from their larger neighbours by the reduced spatial variability of benthic foraminiferal assemblages, living assemblages only distinguishing coral-rich and coral-barren areas. The ecological needs of corals are highlighted by the abundance of Alabaminella weddellensis and Nonionella iridea, phytodetritus-feeding species in coral supporting sediments. Living foraminifera in sediments from the Moira Mounds concentrate in the upper first centimetre. Infaunal species may be affected by bioturbation and/or reworking by the strong currents in the area. Dead foraminiferal assemblages from the Moira Mounds resemble those described for the sandwave facies in adjacent giant mounds, suggesting similar processes in facies deposition.

Chemical Stability: Browning and Oxidation

A number of food components are sensitive to deteriorative reactions, such as nonenzymatic browning and oxidation, during food storage. Food components, i.e., carbohydrates, lipids, proteins and water undergo changes due to the surrounding atmosphere, the presence of minor components and catalysts, and variations in local reactant concentrations resulting from changes in temperature, water migration, and the state of the components. Bioactive proteins and peptides may participate in nonenzymatic browning and oxidation reactions. Oil-soluble bioactive components, for example carotenoids, need protection against oxidation. Water content, and often the physical state of components as well as food structure, may have a significant impact on bioactive stability during food manufacturing and storage.