چكيده لاتين :
1Introduction: Increasing diet-linked diseases and following that the consumers ongoing desire for healthier foods makes reduced-fat products of outstanding importance in the food industry. This study aims to reduce the fat content of sauces as a traditional condiment through the incorporation of air bubbles in the oil phase. Response surface
methodology (RSM) was used for identifying the effect of aeration process variables on foam properties. However, the
main challenge of reduced-fat foods is to ensure their acceptability. Recently fat taste has been introduced as a sixth
basic taste. Fatty acids have been considered as the stimulus for this taste. So, linoleic acid as the stimulus for fat
perception was added to the formulation to develop a product that tastes almost like full-fat versions but contains less
fat. The advantages of aerated foods over conventional products are clear. Nonetheless, the determination of quality and
sensory parameters during storage, marketing, and consuming is necessary. For this purpose, produced aerated sauces,
along with commercial full- and reduced-fat sauces, were compared by measuring the acidity, pH, oxidative stability,
and sensory properties.
Materials and Methods: Required amounts of mono- and diglyceride (MDG) and oil were mixed. Then
nonaqueous foams were generated by whipping the MDG-oil mixtures. In the optimization study, the effect of MDG
concentrations (2, 6, and 10 wt. %), whipping speed (1100, 3250, and 5400 rpm) and time (5, 15, and 25 min) on foam
properties (overrun and drainage) was analyzed using RSM. The foam obtained from the optimum process condition
was used to produce an aerated reduced-fat sauce. Sauce preparation was performed according to a usual recipe with the
difference that the fat content was replaced by nonaqueous foam. Furthermore, 3.00 mM of linoleic acid as a fat taste
stimulus was added to the formulation. First, an aqueous phase containing ingredients was prepared. Then nonaqueous
foam was progressively incorporated in the aqueous phase. For the purposes of comparison, aerated sauces (0 and 3.00
mM stimulus), along with commercial sauces (zero, low, and full-fat), were analyzed by measuring the pH, acidity,
oxidative stability, and sensory properties. Results and Discussion: According to the results of the optimization study, the desired foam (overrun ≥ 60 %)
achieved by oil containing 10 wt. % MDG at 3400 rpm for 10 min. Overrun increased progressively with MDG
concentration but decreased slightly above 10 wt. % due to the difficulty of dispersing air bubbles in such a viscous gel.
Considering the effect of whipping speed, and time, it was observed that mixtures reached their maximum volumes
within 25 min. With a further increase in the whipping rate, the time required to achieve the maximum amount of foam
was decreased. However, at high whipping speed (5400 rpm), foam volume decreased rapidly with time, and almost a
lot of foam collapsed. The lowest and highest pH was related to zero and full-fat commercial sauces, respectively. There
was no difference (p>0.05) between the pH of the control and the linoleic acid containing aerated, as well as low-fat
sauces. Over time, as the pH decreases, the acidity of the aerated sauces increased and making the products with appropriate microbial stability. Due to the significant reduction of fat amount, oxidation of the aerated sauces was much
slower than the full-fat one (p<0.05). Appearance, taste, and texture characteristics of aerated sauces provided a sensory
profile similar to the full-fat sauce. The aerated sauce containing linoleic acid had higher sensory scores, indicating its
general acceptance.
Conclusions: In this study, nonaqueous foam as a new approach for fat replacement in emulsion-based foods such
as sauces was practically applied. The optimum aeration process conditions were determined by the help of
experimental design. Two types of aerated sauces were prepared based on the linoleic acid concentration, and their
physicochemical and sensory characteristics were compared with commercial sauces. The acidity and pH of the sauces
were in the standard range, and also their oxidative stability was acceptable during storage time. Generally, the aerated
sauce containing linoleic acid had relatively similar sensory profiles to the full-fat sauce. Therefore, it seems that
nonaqueous foam could be used successfully to develop reduced-fat alternative foods, which could also be meet the consumers' and marketing requirements.
