Effect of trehalose on the glass transition and ice crystal growth in ice cream

The effects of trehalose and sucrose on the rate of ice crystal growth in ice cream during accelerated shelf‐life were compared. Experimental and theoretical freezing curves were shown to be in good agreement. Glass transition temperatures (T_g) of maximally freeze concentrated trehalose and sucrose solutions (40% w/w) were found to be ?39.5 °C and ?47 °C respectively. For ice cream mixes, the T_g value increased from ?46.4 °C for the 100% sucrose‐based mix to ?42.0 °C for the 100% trehalose sweetened ice cream. However, no differences in viscosity, nucleation rate or inhibition of ice crystal growth were observed with increasing trehalose concentration in ice cream.     

Contribution of thermal,rheological and physical measurements to the determination of sensorially perceived quality of ice cream containing bulk sweeteners

The role of rheological measurements, thermal analysis and physical properties such as overrun, instrumental hardness and melting behavior on sensorial profile mapping of vanilla ice cream was evaluated. Samples with different functional characteristics were prepared partially substituting sucrose by bulk sweeteners. Creaminess apart from thermal properties (glass transition temperature-T_g, ice crystal uniformity-ΔΤ_mcurve and unfrozen water content-UFW) was poorly related with rheological and physical properties. On the contrary, coarseness, wateriness, greasiness and gumminess perception were found to be well correlated with rheological and thermal properties, overrun, air cells mean size and melting rate. Flavor and taste characteristics were interrelated particularly with melting and thermal characteristics, overrun and air cells mean size. Multivariate exploratory statistical methods revealed that the use of T_g, ΔΤ_mcurve, UFW, instrumental hardness, and melting rate can be used for the effective discrimination of ice creams differing in their sweetener composition suggesting their importance in the design of novel ice cream formulations.     

Properties of dextran as a cryoprotectant in ice cream

In order to determine the usefulness of dextran as a stabilizer in frozen dairy products, ice cream mixes with varying concentrations of this microbial polysaccharide were prepared and tested by sensory, physical and mechanical means. Although previous results had shown that aqueous solutions of dextran exhibited remarkably low viscosities, the addition of dextrans to ice cream mixes resulted in much higher values. This is thought to result from interactions among dextrans, dairy proteins and, perhaps, other stabilizers. Dextran addition effectively increased the T_g of ice cream mixes, indicative of its value as a cryoprotectant. Also, dextran significantly reduced the sensory perception of ‘iciness intensity’ in heat-shocked ice cream samples. This resulted from the ability of dextran to slow ice crystal growth during storage and thermal abuse, as indicated by reduced ice crystal size as compared to a control formulation. However, dextran also produced unwanted firmness and melting characteristics in ice cream that could influence commercial acceptability.     

Rheological properties of reduced-fat and low-fat ice cream containing whey protein isolate and inulin

Instrumental analyses were used to evaluate the rheological properties of regular (10%), reduced-fat (6%) and low-fat (3%) ice cream mixes and frozen ice creams stored at −18 °C. The reduced-fat and low-fat ice creams were prepared using 4% whey protein isolate (WPI) or 4% inulin as the fat replacement ingredient. The composition, colour, apparent viscosity, consistency coefficient, flow behaviour index, hardness and melting characteristics were measured. No effect of WPI or inulin was obtained on the colour values. Compared with regular ice cream, WPI changed rheological properties, resulting in significantly higher apparent viscosities, consistency indices and greater deviations from Newtonian flow. In addition, both hardness and melting resistance significantly increased by using WPI in reduced-fat and low-fat ice creams. Inulin also increased the hardness in comparison to regular ice cream, but the products made with inulin melted significantly faster than the other samples.     

Physicochemical properties and organoleptic aspects of ice cream enriched with microencapsulated pistachio peel extract

The purpose of this study was to produce a functional ice cream by the addition of microcapsules of pistachio peel extract (MPPE). Various properties of the resulting ice cream were investigated. By increasing the amount of MPPE the total phenolic content and antioxidant activity increased about 2.0‐ and 3.7‐fold, respectively, compared with the control sample. The rheological properties of the mixes were fitted by the Power Law model. All mixes showed non‐Newtonian pseudoplastic behaviour. By increasing the concentration of MPPE, the consistency coefficient (m), viscosity, and shear sensitivity were increased, but the flow behaviour index (n) decreased. The addition of MPPE to ice cream mixes improved the melting resistance, first dripping times and functional properties of ice cream such as antioxidant activity and total phenolic content. The results of the sensory analysis showed that the addition of MPPE had no significant effect on the overall acceptability of the product. Based on our findings, MPPE has the potential to be used as an added‐value ingredient in the ice cream industry to enhance the functional properties of their products.     

Enrichment of probiotic ice cream with different dietary fibers: Structural characteristics and culture viability

This study evaluated the effect of 5 dietary fibers (apple, orange, oat, bamboo, and wheat) on the physicochemical, rheological, and textural characteristics; sensory properties; and culture viability of probiotic ice cream stored at ?18°C for 180 d. The presence of orange and apple fibers increased the titratable acidity, decreased the lightness (color) value of the ice creams, and enhanced the red and yellow coloration. Compared with the control sample, the consistency indices and apparent viscosities of the experimental samples increased with the addition of all dietary fibers except oat fiber. The highest viscosity was obtained in the sample fortified with apple fiber, whereas the ice cream containing orange fiber showed the highest hardness after d 60 of storage. The addition of orange and apple fibers significantly increased melting resistance; however, panelists did not generally like these samples in terms of taste-flavor. All ice creams had viable counts of Lactobacillus acidophilus of ≥7 log cfu/g during storage except the samples with orange and bamboo fiber. Bifidobacterium lactis counts were also found to be >6 log cfu/g in those samples until d 150 of storage.     

NMR assessment of mix and ice cream. Effect of formulation on liquid water and ice

The overall quality of ice creams is often related to the state of water and fat either in liquid or solid state. This work investigates the capacity of low-field NMR spectrometry in characterizing the different behaviours of water protons in mix and in ice cream. Meanwhile, different formulations (types of protein, fat or emulsifier) were tested. The factor which most affected the T₂ and T₁ relaxation time of the liquid water and ice protons was the protein type. Although this effect is well-known on the NMR behaviour of liquid water protons, it has been observed on the solid water protons for the first time. Assessing the behaviour of liquid water already gave new elements for better understanding the mechanisms responsible for the formation and aging of mix and ice cream. The corresponding relaxation time showed no correlation with rheological properties of mixes, indicating that interactions between molecules in suspension (e.g. proteins) and water protons are not involved in. Its changes during cold storage were relevant of a “non-equilibrium” behaviour, which is further discussed in the paper.     

Effects of Lactobacillus rhamnosus GG addition in ice cream

A 2⁴ full factorial experimental design was applied to verify the effects of Lactobacillus rhamnosus GG (LGG) addition in retail-manufactured ice cream stored at two different freezing temperatures (−16°C and −28°C) and containing two different levels of sugar (15–22%) and fat (5–10%). In addition to microbial counts, the pH, acidity, viscosity of the mixes and functional properties of the ice creams were evaluated. Both fresh and frozen-thawed LGG cells underwent preliminary resistance tests to bile, antibiotics and acidity. The LGG strain proved to be highly resistant to most of the stress factors. When the micro-organism was added to ice cream mixes in a quantity of 10⁸ cfu/g, it did not change the overrun, firmness or melting behaviour of the finished product. Regardless of formulation, no count decay of LGG cells was observed in ice cream stored for up to 1 year.     

Influence of pumpkin puree and guar gum on the bioactive,rheological, thermal and sensory properties of ice cream

The effects of pumpkin puree and guar gum on the bioactive, rheological, thermal and sensory properties of ice cream were investigated. The addition of pumpkin puree increased total phenolic content, dietary fibre, and antioxidant activity. Appropriate models described shear thinning and thixotropic behaviours of all mixes. By either adding pumpkin puree or by increasing guar gum concentration, all rheological properties increased except the flow behaviour index. Adding pumpkin puree reduced the freezing point temperature, ice content, frozen water and glass transition temperature but it increased unfreezable water. Increasing guar gum concentration did not alter colour and firmness, whereas the pumpkin puree increased colour, intensity of fruit flavours and firmness.     

Relationships between ice cream mix viscoelasticity and ice crystal growth in ice cream

The relationship between ice cream mix viscoelasticity and ice crystal growth in ice cream as a function of stabilizer addition was studied by a simulation of freeze-concentration using a series of ice cream mixes containing reduced quantities of water. Ice cream mixes were formulated with guar gum concentrations ranging from 0 to 0.25% and a series of concentrated mixes from each initial formulation was prepared for viscoelastic measurements by successively decreasing the water content. By plotting apparent viscosity or storage modulus against concentration factor based on water removed, a change in slope (breakpoint) could be seen. Ice crystal size analysis in ice cream before and after heat shock testing showed a minimum in recrystallization rate when the concentration of guar gum was 0.14% in the mix. At lower or higher concentrations the recrystallization rate was higher. Normalized breakpoint viscosity correlated well with recrystallization rate. Thus, it appears that stabilizer contributes to recrystallization protection in ice due to a change in polysaccharide behaviour that results from freeze-concentration.     

The effect of using a whey protein fat replacer on textural and sensory characteristics of low-fat vanilla ice cream

The purpose of this research was to evaluate the texture of regular (12%), low fat (6%), and fat-free vanilla (0.5%) ice creams by sensory and instrumental analyses. The low fat and fat free ice cream were prepared using a whey protein based fat replacer (Simplesse ^® 100) as the fat replacement ingredient. Two processing trials with continuous commercial-like process conditions were undertaken. Sensory analyses disclosed that ice creams containing 6% of fat replacer in place of or with milk fat had no demonstrable effect on vanillin flavour. While the sensory attributes of the low fat samples were comparable to the regular vanilla ice cream, the trained sensory panel rated the fat free ice cream to have lower viscosity, smoothness and mouth coating properties. Instrumentally determined apparent viscosity data supported the sensory data. Compared with the fat replacer, milk fat significantly increased the fresh milk and cream flavours of the ice cream. Results emphasized the importance of fat as a flavour modifier and the improvement of texture by addition of Simplesse ^® 100.     

Production of functional probiotic, prebiotic, and synbiotic ice creams

In this work, 3 types of ice cream were produced: a probiotic ice cream produced by adding potentially probiotic microorganisms such as Lactobacillus casei and Lactobacillus rhamnosus; a prebiotic ice cream produced by adding inulin, a prebiotic substrate; and a synbiotic ice cream produced by adding probiotic microorganisms and inulin in combination. In addition to microbial counts, pH, acidity, and physical and functional properties of the ice creams were evaluated. The experimental ice creams preserved the probiotic bacteria and had counts of viable lactic acid bacteria after frozen storage that met the minimum required to achieve probiotic effects. Moreover, most of the ice creams showed good nutritional and sensory properties, with the best results obtained with Lb. casei and 2.5% inulin.     

Probiotic properties of ice creams produced with dietary fibres from by‐products of the food industry

The objective of this study was to investigate the effects of adding dietary fibre‐rich by‐products to probiotic ice creams. For this purpose, fruit (grape, apricot, apple)‐ and grain (rice, corn, sunflower, barley)‐based by‐products were added to ice cream. The viability of Lactobacillus acidophilus (ATCC 4357D‐5) and Bifidobacterium animalis subsp. lactis (ATCC 27536) was determined with microbial analyses at 1, 15, 30 and 60 days of storage. In conclusion, it was shown that dietary fibre‐rich by‐products could be used in ice cream with improved survival of the probiotic strains without any adverse effects on the physicochemical, microbiological and sensory properties of the ice cream.     

The effect of inulin as a fat replacer on the quality of low‐fat ice cream

The influence of different levels of inulin as fat replacer on the quality of ice cream was investigated. Inulin was added at 2, 4 and 6% to replace milk fat and the experimental ice creams were compared to a control with 10% milk fat. The chemical composition, overrun, water activity, viscosity, melting rate, hardness and colour value were determined. Sensory properties of the ice cream samples were evaluated during storage. The overall acceptability of ice creams prepared with 2 and 4% substitution were similar to the control.     

Effects of inulin and oligofructose on the rheological characteristics and probiotic culture survival in low-fat probiotic ice cream

ABSTRACT:  The effects of supplementation of oligofructose or inulin on the rheological characteristics and survival of Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 in low-fat ice cream stored at –18 °C for 90 d were studied. Addition of oligofructose or inulin to ice cream mix significantly increased apparent viscosity and overrun and developed the melting properties in ice cream during storage ( P < 0.05). However, the highest increase in firmness, the lowest change in melting properties, and the longest 1st dripping time were obtained in probiotic ice cream containing inulin ( P < 0.05). Some textural properties have also improved especially by the end of storage. Freezing process caused a significant decrease in the viability of Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 ( P < 0.05). Oligofructose significantly improved the viability of L. acidophilus La-5 and B. animalis Bb-12 in ice cream mix ( P < 0.05). Although the viable numbers for both bacteria decreased throughout the storage, the minimum level of 10⁶ CFU/g was maintained for B. animalis Bb-12 in only ice cream with oligofructose during storage.     

Thermal properties of batter systems formulated by combinations of different flours

There is an increasing consumer preference for reduced oil content in fried food products. The amount of fat absorbed by deep fried foods can be modified using appropriate coatings such as batter and breading systems. Coatings also change the heat transfer characteristics of the composite products. The goal of this study was to determine some thermal properties of selected batter mixes that are commonly used for deep fat frying of chicken products. Three types of flour-based batter mixes were used. These were mixtures of wheat and rice (WR), wheat and corn (WC), and corn and rice (CR) flours with salt and different methylcellulose (MC) levels. The differential scanning calorimeter (DSC) was used to measure glass transition temperature (T_g), gelatinization temperature (T_G), ice-melting temperature (T_m) and enthalpy (ΔH_G) of the different batter formulations. Salt and MC greatly influenced the thermal properties of batter systems as they increased T_G, but depressed T_m. Adding rice and corn flours to wheat flour based batters apparently changed the thermal properties. Corn flour based batters required considerable more energy for gelatinization during the cooking process.     

The effect of inulin on the physicochemical properties and sensory attributes of low-fat ice cream

The aim of this study was to investigate the feasibility of replacing the ice cream fat with inulin to produce a low-fat ice cream with prebiotic properties. For this purpose, inulin (2, 3 and 4%, w/w) was added to the low-fat ice cream and the physicochemical and sensory properties of the resultant ice creams were compared with those of control ice cream (containing 10% fat) and the inulin-free low-fat ice cream. The composition, pH and acidity of the ice cream mixes were measured and the melting rate, colour and texture of the frozen ice cream samples were examined. The results indicated that the low-fat ice creams had a significantly lower melting rate in comparison with the control. Inulin addition caused the adhesiveness and hardness of the low-fat ice creams to decrease significantly compared with inulin-free low-fat ice cream.     

Effect of water uptake on amorphous inulin properties

Physical property changes of amorphous spray-dried inulin were investigated during water uptake at 20 °C. Modulated Differential Scanning Calorimetry (MDSC) and Wide Angle X-ray Scattering (WAXS) were used to investigate the evolution of the glass transition temperature (T_g) and the crystallinity index, respectively. The water content, crystallization and thermal properties relationship enabled the identification of three zones in the T_g–water content state diagram. Zone I delimited inulin in a glassy amorphous state, while zone II characterized inulin in a liquid amorphous state. Inulin crystallized and caked when T_g was below the storage temperature of 20 °C, but crystallization (zone III) was not spontaneous and was delayed by the defined zone II. The crystallization led to thermograms with an endotherm close to T_g. Temperature-Resolved WAXS allowed to correctly ascertain the MDSC endothermic peak as a melting peak because the crystallinity index was maximal at onset temperature of the transition, and dropped to zero at the endset temperature.     

The functional, rheological and sensory characteristics of ice creams with various fat replacers

The effects of fat replacers (Simplesse® D-100, N-Lite D, and inulin) on the melting characteristics, overruns, hardness, rheological parameters and sensory attributes of reduced (RF, 60.0 g/kg), low (LF, 40.0 g/kg), and nonfat (NF, 1.0 g/kg) ice creams were investigated. The magnitudes of the melting rates were in the order RF>LF>NF for samples that contained Simplesse® D-100 or inulin, but the reverse order was found for samples with N-Lite D. The nonfat ice creams had lowest overrun values of around 10%. Inulin-containing ice creams possessed higher overrun values than others ( P  > 0.05). The use of fat replacer decreased the hardness of ice creams. All ice cream samples showed pseudoplastic (shear-thinning) behavior. The addition of N-Lite D and inulin decreased the flow behaviour index of ice cream samples. The reduced and low fat ice cream samples were rated as similar to the control by a sensory panel. On the other hand, no correlations ( P  > 0.05) were observed between rheological parameters and sensory texture and mouthfeel.     

Rubber-to-glass transitions in high sugar/biopolymer mixtures

The confectionery and ice cream industries rely heavily on hydrocolloids to formulate products with superior textural characteristics. Recent studies have mapped out the structural properties of polysaccharides in the presence of increasing levels of sugar. These show that, in contrast to gelatin, there is a dramatic reduction in the structural order of the biopolymer network at high sugar levels. The viscoelasticity of high sugar/polysaccharide systems is an excellent example of the importance of the ‘food-polymer science approach’. The application of free volume theory to mechanical spectra allows a rheological glass transition temperature (T_g) to be obtained. This differs from the T_g determined by calorimetry since the former is affected by the presence of low levels of a network forming biopolymer whereas the latter is not. A comparison of the rheological and calorimetric determined glass transitions offers a new insight into the structure and mechanical properties of this class of foodstuff.