بهينه‌ سازي فرآيند توليد سس هوا دهي شده كم‌ چرب به روش سطح پاسخ و ارزيابي ويژگي‌هاي فيزيكوشيميايي و حسي آن

Optimization of reduced-fat aerated sauce production process by response surface methodology and evaluation of its physicochemical and sensory properties

در اين مطالعه روش جديد آماده سازي امولسيون‌هاي هوا در روغن (كف‌هاي روغني) به‌منظور جايگزيني قطره‌هاي چربي با حباب‌هاي هوا ارائه شده، اثر غلظت سورفكتانت، سرعت و زمان هوادهي بر ميزان توليد و پايداري كف‌ها بررسي شد. شرايط بهينه توليد (هوادهي مخلوط 10 درصد وزني سورفكتانت با سرعت 3400 دور در دقيقه به مدت 15 دقيقه) با روش سطح پاسخ تعيين و كف‌ها براي توليد سس هوادهي شده آماده شدند. لينولئيك اسيد به‌عنوان محرك مزه چربي (صفر و 3 ميلي مولار) به سس‌ها اضافه و ويژگي‌هاي فيزيكوشيميايي و حسي آن‌ها با سس‌هاي تجاري مقايسه شد. اسيديته و pH نمونه‌ها در محدوده استاندارد قرار داشتند. بيشترين ميزان pH مربوط به سس تجاري پرچرب بود (0/0001p<). سس تجاري بدون چربي با كم‌ترين ميزان pH، اختلاف معني‌داري با بقيه نداشت (0/05p>). بين pH سس‌هاي هوادهي شده (شاهد و حاوي لينولئيك اسيد) اختلافي مشاهده نشد. اگرچه با گذشت زمان pH اين سس‌ها كمي كاهش يافت، اما اين تغيير معني‌دار نبود (0/05p>). اعداد پراكسيد و مقادير مالون دي آلدهيد نمونه‌هاي هوادهي شده و تجاري كم‌چرب در مدت هفت روز اختلافي با يكديگر نداشتند (0/05p>). به‌طوركلي، روند اكسيداسيون سس پرچرب بسيار سريع‌تر از ساير نمونه‌ها بود. ظاهر، طعم و ويژگي‌هاي بافتي و پذيرش كلي محصولات هوادهي شده و نمونه‌هاي تجاري ارزيابي شد. پذيرش كلي سس هوادهي شده شاهد با سس حاوي لينولئيك اسيد اختلاف قابل توجهي داشت (0/001p <)، اما پذيرش كلي نمونه حاوي لينولئيك اسيد با سس‌هاي تجاري كم‌چرب و پرچرب معني‌دار نبود (0/05p>). بر اساس اين نتايج جايگزيني حباب‌هاي هوا و نيز افزودن محرك مزه چربي در چارچوب برنامه‌هاي كاهش چربي، مي‌تواند تغييرات حسي موثر بر پذيرش مصرف‌كنندگان را به حداقل برساند.

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.