اثر پودر پنیر و امواج فراصوت بر ویژگی‏های فیزیکوشیمیایی و حسی کیک روغنی بدون گلوتن

در این تحقیق از پودر پنیر در چهار سطح صفر، 3، 6 و 9 درصد و امواج فراصوت با شدت صفر، 30 و 70 درصد جهت بهبود کیفیت کیک روغنی بر پایه مخلوطی از آردهای بدون گلوتن برنج (70 درصد)، کینوآ جوانه‏زده (15 درصد) و سیب‏زمینی (15 درصد) استفاده شد و رطوبت، حجم مخصوص، سفتی بافت، رنگ پوسته و بافت درونی، ویژگی‏های حسی (فرم و شکل، خصوصیات سطح بالایی و پائینی، پوکی و تخلخل، سفتی و نرمی بافت، عطر و مزه و پذیرش کلی)، تخلخل و ریز ساختار نمونه‏های تولیدی ارزیابی گردید. نتایج نشان داد، افزایش پودر پنیر و شدت امواج فراصوت سبب افزایش کیک‏ از 17.9 درصد (نمونه شاهد) به 25.1 درصد (نمونه 9 درصد پودر پنیرشدت صوت 70 درصد) شد. این در حالی بود که نمونه حاوی 6 درصد پودر پنیر و تحت تاثیر امواج فراصوت با شدت 30 درصد از حجم مخصوص (4.4 سانتی‏متر مکعب بر گرم) و تخلخل (31.1 درصد) بیشتر و سفتی بافت کمتری (به‌ترتیب 3.4 و 5.3 نیتوتن در بازه زمانی 2 ساعت و یک هفته پس از پخت) در مقایسه با سایر نمونه‏ها برخوردار بود. همچنین نتایج نشان داد، افزایش پودر پنیر تا 6 درصد سبب افزایش مولفه l* (از 44.9 به 53.5) و تا سطح 9 درصد سبب افزایش مولفه a* (از 2.6 به 8.4) پوسته کیک‏های بدون گلوتن تولیدی شد. از سوی دیگر نتایج حاکی از آن بود که افزایش درصد شدت امواج فراصوت منجر به افزایش مولفه رنگی l* (از 60.3 به 77.9) و کاهش مولفه رنگی b* (17.3 به 7.9) بافت درونی کیک‏های بدون گلوتن شد. یافته‏های به‌دست آمده از ارزیابی حسی و امتیاز پذیرش کلی نیز حاکی از برتری نمونه‏های حاوی 3 و 6 درصد پودر پنیر تحت تاثیر امواج فراصوت با شدت 30 درصد به‌ترتیب با امتیاز 4.2 و 4.4 بود. همچنین بررسی تصاویر میکروسکوپ الکترونی و تصاویر دودویی نمونه‏های برتر (ریزساختار میکروساختار) گواه انسجام و پیوستگی ساختار درونی و شبه شبکه موجود در کیک‏های بدون گلوتن حاوی پودر پنیر در مقایسه با شاهد بود.

Evaluation of the effect of cheese powder and ultrasonic wave on physicochemical and sensory properties of gluten-free oil cake

Introduction: Celiac disease leads to the malabsorption of nutrients and damage to intestinal mucosa. High nutritional value is one of the advantages of dairy powders, associated with their high calcium, protein and essential amino acid contents. Research has shown that such powders boost the gluten quasinetwork by forming interfacial films. They are also able to increase the moisture, improve the organoleptic properties, and retard the staling of glutenfree bakery products. In addition, it has been reported that ultrasonic waves can accelerate the oxidation and increase the aeration, volume, porosity and moisture content of bakery products. They can also reduce the hardness and improve the color of such products, thus resulting in the enhancement of their quality and marketability. Consequently, the aim of this study was to improve the appearance, flavor and texture of the glutenfree cake based on rice, germinated quinoa and potato flour using cheese powder at 0, 3, 6 and 9% and ultrasound intensity of 0, 30 and 70% for 5 min. Material and methods: In this study, cheese powder at 0, 3, 6 and 9% and ultrasound intensity of 0, 30 and 70% for 5 min were used to improve the quality of glutenfree cupcake. Control cake formulation had 70 g rice flour, 15 g germinated quinoa flour, 15 g potato flour, 52 g sugar, 50 g water, 36 g egg, 36 g oil, 12 g invert syrup, 2 g baking powder, 0.2 g vanilla, 1.5 g guar gum and 0.5 g xanthan gum. Moisture, specific volume, firmness, crust and crumb color, sensory properties, porosity and scanning electron microscopy (SEM) (with 100× magnification) were evaluated. To study the effect of processing parameters on color components of glutenfree cupcake, the RGB color space images were converted to L*a*b space. For determination of glutenfree cupcake porosity using image analysis, the color images were first gray scaled and then thresholded using isodata algorithm. The porosity was measured from the ratio of white to the total numbers of pixels. Results were reported as the average of three replications. In order to assess significant differences among samples, a complete randomized design of triplicate analyses of samples was performed using the MiniTab17. Turkey’s new multiple range tests were used to study the statistical differences of the means with 95% confidence. Result and discussion: Results revealed that moisture content increased as the cheese powder and ultrasound intensity were elevated. Cheese powder caused the moisture content to increase by boosting the gluten quasinetwork and ultrasonic waves brought about this phenomenon by dissociating the polymeric chains of starch molecules and forming hydrogen bonds between water molecules and free hydroxyl groups. The sample containing 6% cheese powder sonicated at 30% intensity had higher specific volume (4/4 Cm3/g) and porosity (31.2%) as well as lower hardness (3.4 and 4.4 N after 2 hours and one week respectively) compared with other samples. Cheese powder, by boosting the gluten quasinetwork and improving the dough elastic properties, and ultrasound, through enlarging the air bubbles present in the dough, caused an increase in the porosity, specific volume and softness. The results also indicated that the rise in the cheese powder content up to 6% led to an increase in the L* value (from 44.9 to 53.5) and up to 9% in the a* value (from 2.6 to 8.4) of the glutenfree cupcake crust. On the other hand, the results demonstrated that as the ultrasonic intensity was increased, the L* value of the glutenfree cupcake crumb also increased (from 60.3 to 77.9), while its b* value was reduced (from 17.3 to 7.9). This could be due to the aeration and oxidation acceleration which resulted in the increased whiteness and decreased yellowness of the cake crumb. Finally, the findings of sensory evaluation showed the preference of the samples containing 3 and 6% cheese powder sonicated at 30% intensity (4.2 and 4.4 score). The SEM and binary images of the preferred samples also confirmed the integrity of the internal structure and the gluten quasinetwork of these samples, compared with the control.