Impact of antioxidants dispersions on the stability and oxidation of water-in-olive-oil emulsions

Water-in-olive-oil emulsion stability was studied as a function of the composition of the water dispersed phase. In particular, different polyphenolic extracts from natural sources were dispersed in the olive oil and their impact on emulsion kinetic stability and susceptibility to oxidation was evaluated. As natural sources, extra virgin olive oil, olive mill waste and green tea leaves were chosen. To test their impact on emulsion properties, the emulsions were prepared with fixed aqueous phase content. As emulsifiers, a fixed percentage of a mixture Span 80 (sorbitan monoleate)/Tween 80 (polysorbate 80) was used. The effect of the antioxidant dispersion on emulsion oxidation was studied by triggering the oxidation reaction in the oil phase with the lipophilic radical initiator AMVN (2,2-azobis(2,4-dimethylvaleronitrile). Then, the oxidation reaction was followed by using diphenyl-1-pyrenylphosphine, which becomes fluorescent when it is oxidized by hydroperoxides. The impact of antioxidant dispersions on emulsion kinetic stability was studied by UV–Vis turbidity measurements. The oxidation results were correlated to antioxidant extracts oxygen radical adsorption capacity (ORAC) and to emulsion kinetic stability. On the whole, antioxidants dispersions delayed the oxidation reaction to different extents in dependence on their ORAC values and their components amphiphilicity. Remarkably, among the antioxidants tested, the aqueous polyphenol extract from virgin olive oil was the most effective because it protected emulsions both from oxidation and from phase separation. Additionally, from this set of experiments, the primary role of the interfacial properties of olive oil polyphenols was highlighted.     

Can a structured emulsion (fat in water-fibre system) substitute saturated fat in cookies without hampering their quality?

Replacing fat and saturated fat in baked goods without affecting their quality characteristics is a challenging task. This study evaluated complete and partial substitution of saturated fats (butter and palm oil) by structured emulsions [SE, oil (sunflower) – in – water (fibre-water) emulsion] in cookies by investigating its impact on product quality. Nutritional labelling underlined a drastic reduction in saturated fatty acids [−35% (50% substitution) and −73% (100% substitution)] compared to their conventional counterparts (butter and palm oil). Partial substitution did not markedly affect physicochemical properties, while complete substitution resulted in thinner, harder and darker cookies compared to the controls. Particularly, cookies made with (50:50) structured emulsion – palm oil had the highest sensory scores, and they were perceived as soft, buttery and crunchy. Thus, the use of structured emulsion might be a valuable alternative to develop a potentially healthier product with acceptable sensory properties.     

A multi-scale characterisation of the durum wheat pasta cooking process

A multi-level investigation was carried out to characterise uncooked to overcooked pasta. Macroscopic, mesoscopic and molecular properties were measured and their changes were clearly related to the process of cooking: hardness and viscoelastic decreased, moisture content and gelatinisation degree increased and ¹H molecular mobility changed. Principal component analysis (PCA) explained 82% (PC1: 47.7% and PC2: 34.3%), enabling the differentiation by cluster of different cooking phases: uncooked, undercooked (described by degree of gelatinisation and rigid protons’ populations [FID and T₂]); medium-cooked (described by higher mobility protons [T₂E1, T₂E2 and %PopE2]), cooked at suggested cooking time (described by viscoelastic properties) and over-cooked pasta by molecular mobility parameters (T₂D, T₂E and %PopF). Nuclear magnetic resonance relaxometry was a valuable tool to describe the entire cooking process, whereas viscoelastic properties effectively characterised suggested cooking time.