ABSTRACT
Biscuits contain high proportions of saturated fats, which could lead to an adverse health effect. The objective of this study was to study the functionality of a complex nanoemulsion (CNE), stabilised with hydroxypropyl methylcellulose and lecithin, when used as a saturated fat replacer in short dough biscuits. Four biscuit formulations were studied including a control (butter) and three formulations where 33% of the butter was replaced with either extra virgin olive oil (EVOO), with CNE, or with the individual ingredients of the nanoemulsion added separately (INE). The biscuits were evaluated by texture analysis, microstructural characterisation, and quantitative descriptive analysis by a trained sensory panel. The results showed that incorporation of CNE and INE yielded doughs and biscuits with significantly higher (p < 0.05) hardness and fracture strength values than the control. The doughs made of CNE and INE showed significantly less oil migration during the storage than EVOO formulations, which was confirmed by the confocal images. The trained panel did not find significant differences in crumb density and hardness on the first bite among CNE, INE and the control. In conclusion, nanoemulsions stabilised with hydroxypropyl methylcellulose (HPMC) and lecithin can work as saturated fat replacers in short dough biscuits, providing satisfactory physical characteristics and sensory attributes.
ABSTRACT
The combination of two emulsifiers, lecithin and hydroxypropyl methylcellulose (HPMC), into emulsions is an interesting strategy to design fat replacers in food matrices. The objective of this study was to investigate the effect of HPMC type and concentration on the formation, stability, and microstructure of conventional emulsions and nanoemulsions. Two different types of HPMC with low and high content of methyl and hydroxypropyl groups (HPMC-L and HPMC-H) were evaluated. The results showed that the molecular structure and concentration of HPMC play a major role in the viscoelastic behaviour, the gelation temperature, and the strength of gel formed. The firmness and work of shear of HPMC solutions increased significantly (p < 0.05) with increasing concentration. HPMC-L illustrated a more stable gel structure than the HPMC-H solution. Nanoemulsions showed lower moduli values, firmness, and work of shear than conventional emulsions due to the influence of high-pressure homogenization. A combination of lecithin and HPMC improved the physical and lipid oxidative stability of the emulsions, presenting a lower creaming index and thiobarbituric acid reactive substances (TBARS). In conclusion, HPMC-L at 2% w/w could be a suitable type and concentration combined with lecithin to formulate a saturated fat replacer that could mimic butter technological performance during food manufacturing operations.
ABSTRACT
The processes of oil production play an important role in defining the final physical and chemical properties of vegetable oils, which have an influence on the formation and characteristics of emulsions. The objective of this work was to investigate the correlations between oils' physical and chemical properties with the stability of conventional emulsions (d > 200 nm) and nanoemulsions (d < 200 nm). Five vegetable oils obtained from different production processes and with high proportion of unsaturated fatty acids were studied. Extra virgin olive oil (EVOO), cold-pressed rapeseed oil (CPRO), refined olive oil (OO), refined rapeseed oil (RO) and refined sunflower oil (SO) were used in this study. The results showed that the physicochemical stability of emulsion was affected by fatty acid composition, the presence of antioxidants, free fatty acids and droplet size. There was a significant positive correlation (p < 0.05) between the fraction of unsaturated fatty acids and emulsion oxidative stability, where SO, OO and EVOO showed a significantly higher lipid oxidative stability compared to RO and CPRO emulsions. Nanoemulsions with a smaller droplet size showed better physical stability than conventional emulsions. However, there was not a significant correlation between the oxidative stability of emulsions, droplet size and antioxidant capacity of oils.
