ICE CREAMS

Icecreams are considered as foams that a slightly frozen emulsion covers the air cells of the colloidal system. The foam quality and subsequently the texture and structure of Ice-cream can be affected by some factors like total solid and milk fat compositions, and the characteristics of ice crystal/ fat particles dispersion such as the size and state. In addition, the important quality properties including viscosity, creaminess, hardness, ice crystallization, meltability, and flavor are affected upon fat decrement of the formulation of frozen dairy products (El-Nagar et al., 2002). Thus, there are some successfully reports regarding the critical role of prebiotics as fat replacers in Ice-cream formulations (Table 3.1). Schaller-Povolny and Smith (1999) found an increased chewiness and reduced sweetness and vanilla flavor intensity perception of reduced-fat Ice-cream upon substituting 50% or 100% of 42 DE (dextrose equivalent) corn syrup with inulin. The formation of ice crystals over a 42 days thermal abuse period was also inhibited by partial or complete substitution of com syrup with inulin. The effects of inulin or oligofructose on the rheological attributes of low-fat Ice-cream have also been reported by some researchers (Akahn and Erisir, 2008). The results of this study showed that the addition of inulin or oligofructose to an ice-cream mix led to an increase in apparent viscosity and overrun and improve in melting properties of the product during storage at -18°C for 90 days. In addition, inulin-fortified Ice-cream presented the highest firmness and the lowest change in melting characteristics. Eventually, they reported that the fortification process improved some textural attributes especially by the end of the storage period. In a similar study, the effects of dietaiy fiber sources like oat, wheat, apple, and inulin on the rheological and thermal attributes of Ice-cream were evaluated (Soukoulis et al., 2009). The viscosity and shear-thinning behavior of an Ice-cream was increased by the content of fiber in insoluble materials. As the number of soluble materials increased, the rheology of the products was not altered significantly, but limited the depression of freezing point and increased the glass transition temperature (T) due to their cryoprotective effects. The water-binding capacity of oat and wheat fibers resulted in a product with high viscosity, while a significantly T increment was observed in the presence of inulin. The use of apple fiber also led to an increase in viscosity and T. It can be concluded from the results of this study that dietaiy fibers, besides their nutritional and functional roles, can be used as controller agents for crystallization and recrystallization phenomena (Soukoulis et al., 2009). Addition of inulin and lactulose to low-calorie functional ice creams did not affect the total solids, pH value, meltdown rate, and sensory attributes of the product, while leading to an increase in overrun and hardness of the low-fat samples (Hashemi et al., 2015). Javidi et al. (2016) studied the effects of basil seed gum, guar gum, and their blend (50:50) at incorporation levels of 0.35, 0.45, 0.50, and 55% on the physical, rheological, and sensorial attributes of low-fat Icecream with 2.5% fat content. Incorporation of gums into low-fat Ice-cream increased the consistency coefficient, thixotropy rate constant, extent of thixotropy, and yield stress and lowered the flow behavior index. In addition, the meltdown rate and extent of melting were reduced at all concentrations upon basil seed gum addition. Inclusion of basil seed gum and their blend resulted in a product with higher shear-sensitive thixotropic nature than that of guar gum mix and significantly improved the creaminess and declined the coldness and coarseness of low-fat product (Javidi et al., 2016). Increased apparent viscosity and decreased melting rate of Ice-cream mixes in the presence of basil seed gum were also reported by Bahram-Parvar et al. (2012). The authors have also used the basil seed gum (0.1 or 0.2%) as a novel stabilizer in an Ice-cream to improve the product texture and reduce the ice recrystallization. Basil seed gum incorporation lowered ice recrystallization and growth rate of ice crystals (30-40%). It also declined the meltdown rate and increased the particle size, which in turn create a different structure likely due to the reduction of air and fat interfacial tensions (IFT) (Bahram-Parvar and Goff, 2013).

 
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