تولید شکلات حباب‌دار و استفاده از مقطع‎نگاری اشعه X و پردازش تصویر در بررسی ویژگی‌های حباب‌ها

نوع مقاله : مقاله پژوهشی

نویسندگان

• مسیح سرفرازی ¹
• محبت محبی ¹
• مهدی سعادتمند طرزجان ²
• علی میرشاهی ³

¹ گروه علوم و صنایع غذایی، دانشکده کشاورزی، دانشگاه فردوسی مشهد.

² گروه مهندسی برق، دانشکده مهندسی، دانشگاه فردوسی مشهد.

³ گروه علوم درمانگاهی، دانشکده دامپزشکی، دانشگاه فردوسی مشهد.

https://doi.org/10.22067/ifstrj.v16i5.83979

چکیده

در این مطالعه، شکر با مخلوط اینولین: مالتودکسترین در نسبت‌های 75:25 (CH2)، 50:50 (CH3) و 25:75 (CH4) جایگزین شد. سپس گاز دی‌اکسید کربن در فشار 6 بار به این سه شکلات علاوه‌بر شکلات حاوی شکر (CH1) تزریق شد تا شکلات حباب‌دار تولید شود. با استفاده از مقطع‌نگاری اشعه X از شکلات‌های حباب‌دار تصویربرداری شد و پس از پردازش، تصاویر به‌دست‎آمده با استفاده از روش چان-وز تقطیع شدند؛ یعنی حباب‌ها از سایر قسمت‌های تصویر جدا شدند. ویژگی‌های حباب‌ها که در این تحقیق موردبررسی قرار گرفتند عبارت بودند از: حجم کل، قطر و نسبت سطح به حجم. همچنین، بلورینگی، چگالی و سختی شکلات‌ها نیز با هم مقایسه شدند. نتایج نشان دادند که روش چان-وز توانست نویزهای موجود در تصویر را حذف کند. همچنین، نتایج پراش اشعه X نشان داد که نمودار CH3 قله‌های تیزتری نسبت به CH2 و CH4 دارد که این نشانی از بلورینگی بیشتر آن بود. میانگین قطر حباب‌های CH1 بیشتر از سایر نمونه‌ها بود که دلیل آن را می‌توان به بلورینگی بیشتر آن در مقایسه با نمونه‌های بدون شکر نسبت داد؛ زیرا ساختار متبلور CH1 از خروج گاز جلوگیری کرده و موجب به‌هم پیوستن حباب های کوچک و تشکیل حباب‌های بزرگتر شده است. همچنین، مشاهده شد که در تمام شکلات‌ها، چگالی شکلات حباب‌دار کمتر از شکلات بدون حباب است؛ زیرا بخشی از مواد جامد و چربی با گاز دی‌اکسید کربن جایگزین شد. نتایج اندازه‌گیری سختی نیز نشان داد که نمونه‌های بدون شکر حباب‌دار از نمونه‌های بدون گاز نرم‎تر بودند ولی در مورد CH1 عکس این پدیده مشاهده شد که دلیل آن را می‌توان به حضور شکر در این نمونه نسبت داد؛ زیرا در محصولات حباب‌دار، ذرات جامد، به‌ویژه شکر، یک اسکلت پیوسته را تشکیل می‌دهند و همان نقشی را ایفا می‌کنند که چربی در محصولات بدون حباب بازی می‌کند.

کلیدواژه‌ها

• اینولین
• مالتودکسترین
• مقطع نگاری اشعه X
• پراش اشعه X
• چان-وز
• سختی

عنوان مقاله [English]

Production of aerated chocolate and application of X-ray computed tomography and image processing in evaluating the bubbles features

نویسندگان [English]

• Messiah Sarfarazi ¹
• Mohebbat Mohebbi ¹
• Mahdi Saadatmand-Tarzjan ²
• Ali Mirshahi ³

¹ Department of Food Science and Technology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.

² Department of Electrical Engineering, Faculty of Engineering, , Ferdowsi University of Mashhad, Mashhad, Iran.

³ Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.

چکیده [English]

Introduction: Chocolate is a suspension of solid particles, including sugar, cocoa solids and milk powder (depending on the chocolate type) in a continuous fat phase, namely cocoa butter or its substitutes. The solid particles account for approximately 70% of chocolate with the fat constituting about 30%. Sugar takes up nearly 40–50% of the total solid particles of chocolate, thus influencing its sweetness, particle size distribution, rheological and sensory properties. It is also considered to be a bulking agent and a source of energy which produces 394 kcal/100 g of refined sugar. Therefore, consumers are increasingly becoming concerned with chocolate sugar and calorie content nowadays. This issue can be resolved by replacing sugar with bulk (nutritive) sweeteners and/or dietary fibers. Bubbles are found in many food products, including cakes, chocolates and beverages. Although they do not increase the food nutritional value, they change its textural properties and mouthfeel. Bubbles are normally visible to the naked eye and their mean diameter ranges from 0.05 to 3 mm. X-ray computed tomography is a 3D imaging technique which captures the images of a sample cross-sections. It is used for the non-destructive visualization and characterization of food microstructure. In this method, a series of radiographs of a sample are captured from different angles to be utilized for the 3D reconstruction of the material microstructure.
 
Materials and methods: sugar was replaced with inulin: maltodextrin mixture at ratios of 25:75 (CH2), 50:50 (CH3) and 75:25 (CH4). Carbon dioxide was injected into the samples at 6 bar to produce aerated chocolate. Using X-ray computed tomography, the images of the samples were captured and after processing, the obtained images were segmented using the Chan-Vese method. The properties of bubbles included total volume, diameter and surface to volume ratio. The crystallinity of the samples was determined through X-ray diffraction. The hardness of the chocolate bars was measured using the puncture test. The density of the aerated chocolates was also compared with that of the nonaerated ones.
 
Introduction: Chocolate is a suspension of solid particles, including sugar, cocoa solids and milk powder (depending on the chocolate type) in a continuous fat phase, namely cocoa butter or its substitutes. The solid particles account for approximately 70% of chocolate with the fat constituting about 30%. Sugar takes up nearly 40–50% of the total solid particles of chocolate, thus influencing its sweetness, particle size distribution, rheological and sensory properties. It is also considered to be a bulking agent and a source of energy which produces 394 kcal/100 g of refined sugar. Therefore, consumers are increasingly becoming concerned with chocolate sugar and calorie content nowadays. This issue can be resolved by replacing sugar with bulk (nutritive) sweeteners and/or dietary fibers. Bubbles are found in many food products, including cakes, chocolates and beverages. Although they do not increase the food nutritional value, they change its textural properties and mouthfeel. Bubbles are normally visible to the naked eye and their mean diameter ranges from 0.05 to 3 mm. X-ray computed tomography is a 3D imaging technique which captures the images of a sample cross-sections. It is used for the non-destructive visualization and characterization of food microstructure. In this method, a series of radiographs of a sample are captured from different angles to be utilized for the 3D reconstruction of the material microstructure.
 
Materials and methods: sugar was replaced with inulin: maltodextrin mixture at ratios of 25:75 (CH2), 50:50 (CH3) and 75:25 (CH4). Carbon dioxide was injected into the samples at 6 bar to produce aerated chocolate. Using X-ray computed tomography, the images of the samples were captured and after processing, the obtained images were segmented using the Chan-Vese method. The properties of bubbles included total volume, diameter and surface to volume ratio. The crystallinity of the samples was determined through X-ray diffraction. The hardness of the chocolate bars was measured using the puncture test. The density of the aerated chocolates was also compared with that of the nonaerated ones.
 
Results and discussion: X-ray diffraction revealed that there were many strong peaks in the diffractogram of CH1, which can be ascribed to the high degree of sugar crystallinity in addition to the impurities present in the commercial sugar utilized in this study. In the case of the sugar-free samples, namely CH2, CH3 and CH4, two distinct peaks could be seen at 2θ of about 21° and 23.5°, both of which were much stronger and more defined in the scattering pattern of CH3, demonstrating the more crystalline structure of this sample. It seems that inulin and maltodextrin have physically interacted with each other or with the other ingredients of the chocolate, in particular CBS, which has been more pronounced at the ratio of 50:50. The results of image segmentation showed that the Chan-Vese method, compared with the adaptive thresholding one, was more able to segment the images, because this method does not depend on the image gradient and is especially suitable for the objects with vague edges. The mean bubble diameter of CH1 was bigger than that of the other samples, which could be due to its higher degree of crystallinity, because the crystalline structure of CH1 prevented the gas from being lost leading to the coalescence of smaller bubbles and the formation of bigger ones. In addition, it was observed that the density of the aerated chocolate was higher than that of the unaerated one in all the formulas as a portion of solid particles and fat was replaced with the gas. The results also demonstrated that the sugar-free aerated samples were softer than the corresponding nonaerated ones. However, it was reversed in the case of CH1 which could be ascribed to the presence of sugar in this sample, because in aerated products, solid particles, particularly sugar, form a continuous skeleton and play the same role as fat does in nonaerated products.

کلیدواژه‌ها [English]

• Inulin
• Maltodextrin
• X-ray computed tomography
• X-ray diffraction
• Chan-Vese
• Hardness

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