Optimization of microbial transglutaminase activity in ice cream using response surface methodology

In order to determine the maximum activity range of transglutaminase (TG) in ice cream, the central composite design was used and the TG concentration along with the reaction time and temperature were evaluated. The rheological behavior of the ice cream mix that provided the best response and the determination of the protein cross-linking by electrophoresis (SDS-PAGE) were evaluated. It was observed that the TG increased the consistency index and favored the pseudoplastic behavior of the ice cream samples. The maximum response (0.69 Pa sⁿ) was obtained using a TG concentration of 4 U g⁻¹ protein at 56.8 °C with a reaction time of 90 min. The protein cross-linking was confirmed by electrophoresis, which showed that κ-casein was more susceptible to attack from TG than whey proteins.     

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.     

Effect of polyphenol from apple peel extract on the survival of probiotics in yoghurt ice cream

The objective of this study was to evaluate the effect of apple peel polyphenol extract (APPE) on the microbiological and physicochemical properties of yoghurt ice cream stored at −20 °C for 90 days. Five level of APPE were added in yoghurt ice cream as: CTL (control without APPE); AE1 (1% APPE); AE2 (2% APPE); AE3 (3% APPE); AE4 (4% APPE); and AE5 (5% APPE). Samples with APPE had viable counts of Lactobacillus acidophilus and Bifidobacterium lactis of ≥8 log cfu g⁻¹ and >7 log cfu g⁻¹, respectively, during 90 days storage except the control sample. The highest viability of probiotics was obtained in the sample fortified with 5% APPE. The presence of APPE increased the acidity, decreased the melting rate and enhanced the overrun. Compared with the control sample, the hardness of the experimental samples increased with the fortification of APPE. The addition of APPE significantly increased sensory attributes.     

Increasing retention of vitamin D3 in vitamin D3 fortified ice cream with milk protein emulsifier

This study aimed to develop vitamin D₃ fortified ice cream by incorporating vitamin D₃ in an emulsified form using milk protein as emulsifier. Physicochemical stability of vitamin D₃ emulsions using different milk protein emulsifiers including nonfat dry milk, sodium caseinate (Na-Cas), and whey protein isolate was investigated. Emulsion using Na-Cas had the smallest oil droplet size and the lowest creaming index throughout the storage time (P < 0.05) and was selected to fortify in full-fat, reduced-fat, and low-fat ice creams at 250 IU per serving. Vitamin D₃ retention in each ice cream was determined after 0, 7, 14, 28 and 56 d of storage at −20 °C. The results indicated that the emulsified form of vitamin D₃ remarkably improved vitamin D₃ stability in all ice cream formulations.     

High hydrostatic pressure modification of whey protein concentrate for improved body and texture of lowfat ice cream

Previous research demonstrated that application of high hydrostatic pressure (HHP), particularly at 300 MPa for 15 min, can enhance foaming properties of whey protein concentrate (WPC). The purpose of this research was to determine the practical impact of HHP-treated WPC on the body and texture of lowfat ice cream. Washington State University (WSU)-WPC was produced by ultrafiltration of fresh separated whey received from the WSU creamery. Commercial whey protein concentrate 35 (WPC 35) powder was reconstituted to equivalent total solids as WSU-WPC (8.23%). Three batches of lowfat ice cream mix were produced to contain WSU-WPC without HHP, WSU-WPC with HHP (300 MPa for 15 min), and WPC 35 without HHP. All lowfat ice cream mixes contained 10% WSU-WPC or WPC 35. Overrun and foam stability of ice cream mixes were determined after whipping for 15 min. Ice creams were produced using standard ice cream ingredients and processing. The hardness of ice creams was determined with a TA-XT2 texture analyzer. Sensory evaluation by balanced reference duo-trio test was carried out using 52 vol.nteers. The ice cream mix containing HHP-treated WSU-WPC exhibited the greatest overrun and foam stability, confirming the effect of HHP on foaming properties of whey proteins in a complex system. Ice cream containing HHP-treated WSU-WPC exhibited significantly greater hardness than ice cream produced with untreated WSU-WPC or WPC 35. Panelists were able to distinguish between ice cream containing HHP-treated WSU-WPC and ice cream containing untreated WPC 35. Improvements of overrun and foam stability were observed when HHP-treated whey protein was used at a concentration as low as 10% (wt/wt) in ice cream mix. The impact of HHP on the functional properties of whey proteins was more pronounced than the impact on sensory properties.     

Novel method of zinc ions supplementing with fermented and unfermented ice cream with using PEF

Bacteria of Lactobacillus rhamnosus B 442 were enriched with zinc ions using a pulsed electric field technology. The strain was added to the mix and used for the production of two types of ice cream: unfermented and fermented. Zinc content in the ice cream varied from 0.962 mg·100 g⁻¹ to 1.81 mg·100 g⁻¹. Differences were observed in some properties of unfermented and fermented ice cream. Lower fat content (from 4.86% to 4.92%) and lower hardness (3.88 N–4.32 N) were determined for the fermented ice cream, whereas the unfermented samples had higher meltability (1880s–1936s) and adhesiveness (from 29.66 Ns to −28.27 Ns). There was no statistically significant effect of the type of ice cream and Zn²⁺ addition on protein, ash and carbohydrate content in the final product. The viability of the bacteria was at a high level (4.09·10⁸–3.26·10¹²).     

Nonfermented ice cream as a carrier for Lactobacillus acidophilus and Lactobacillus rhamnosus

Efficiency of a nonfermented ice cream for delivering Lactobacillus acidophilus and Lactobacillus rhamnosus to consumers was evaluated. Both of the microorganisms survived at the populations of greater than 10⁷ CFU g^?1 during 12 weeks of storage at ?19 °C. Addition of the microorganisms had no significant effect on the overrun, viscosity, firmness and melting behaviour; it changed the acidity, pH and sensory properties of the finished product. Resistance to acid and sensitivity to bile of both bacteria were tested separately on fresh harvested cells before inoculation to ice cream and then on the frozen‐thawed cells after 12 weeks of cold storage in ice cream. Ice cream processing followed by cold storage reduced acid resistance of both bacteria at pH 2.5. Resistance to bile in L. rhamnosus was not affected in frozen‐thawed ice cream when compared to fresh cell, whereas resistance to bile in L. acidophilus appeared to be more susceptible to the process and cold storage.     

Grape wine lees improves the rheological and adds antioxidant properties to ice cream

The effect of adding grape wine lees (GWL) (50, 100 and 150 g kg⁻¹, wet weight basis) on the rheological and antioxidant properties of ice cream was evaluated to determine the potential of using GWL as a value-added ingredient in ice cream. Black queen grape was selected because it was the only species for red winemaking in Taiwan. The addition of GWL decreased the specific gravity, pH, melting rate, firmness, lightness and the amount of freezable water in ice cream, but increased the viscosity, yellowness and fat destabilization in a dose dependent circumstance. However, the ice cream with high GWL contents (100 and 150 g kg⁻¹) also showed unpleasant effects, such as the decrease of overrun and the increase of particle size of fat globule. The level of 50 g kg⁻¹ was applicable because it improved the functionality without the disadvantages in the overrun and particle size. Furthermore, GWL significantly increased the DPPH radical scavenging activity and reducing power of ice cream, and also its inhibitory effect toward the oxidation of human erythrocyte membrane. It appeared that the antioxidants in GWL were quite stable to the process of ice cream making.     

Survival of Lactobacillus johnsonii La1 and influence of its addition in retail-manufactured ice cream produced with different sugar and fat concentrations

After several studies have proved the benefits deriving from the ingestion of probiotic bacteria, various dairy products containing lactobacilli and bifidobacteria cultures have been formulated in recent years. A 2⁴ full factorial experimental design was applied to verify the effects of Lactobacillus johnsonii La1 addition in retail-manufactured ice cream stored at two different freezing temperatures and containing two different levels of sugar and fat. Both fresh and frozen–thawed La1 cells underwent preliminary resistance tests to bile, antibiotics, SDS, and acidity. La1 strain proved to be highly resistant to most of stress factors, thus excluding the possibility to find evidence of cell sublethal injuries caused by freezing. When the microorganism was added to ice cream mixes in the quantity of 10⁷ cfu g⁻¹, it did not modify the overrun and firmness of the finished product. Regardless of formulation, no count decay of La1 cells was observed in ice cream stored for up to 8 months.     

Correlation between colloidal properties of ice cream mix and ice cream

Ice cream mix was produced with a range of emulsifiers and concentrations. Ice cream mix properties were measured and correlated to ice cream properties. Protein load (mg m⁻²) in ice cream mix correlated with major characteristic analyses describing the fat structure in ice cream (fat agglomerate size, fat agglomeration index, solvent extractable fat). Thus, the measurement of protein load in the mix can be used to predict ice cream fat stability and related structure with constant processing conditions. As emulsification increased, more fat could be seen at the air interface by scanning electron microscopy. High correlation coefficients were also obtained with fat structure analyses and the quantitative determination of fat in the dripped portion taken from a melting test of ice cream. Hence, fat analysis from the dripped melt fraction is suggested as a method to characterize the fat-related structure in ice cream.     

Influence of Cape gooseberry (Physalis peruviana L.) addition on the chemical and sensory characteristics and mineral concentrations of ice cream

In this research, the influence of Cape gooseberry (CG) addition at different concentrations (5, 10 and 15%) on the physical, chemical and sensory properties and mineral contents of ice cream was investigated. The increment of CG concentration caused the decrease of fat, protein, pH and overrun values in ice cream, on the contrary it increased the total solid, ash, titratable acidity, viscosity values and first dripping and complete melting times. S contents of ice creams significantly increased with the CG addition. Moreover, CG increased K, and Na concentrations of ice cream, while lowered Ca and P contents. Mg contents of ice creams didn't change with CG addition (P > 0.05). Fe, Zn, Mn and Ni were determined as minor elements in ice cream samples and a significant increase was observed in Fe, Zn and Mn values (P < 0.05). The addition of CG did not affect Ni content of ice creams. The sensory results indicated that the ice cream containing 15% CG was the highest-scored by the panelists.     

The effect of soy protein concentrate addition on the physical, chemical, and sensory properties of strawberry flavored ice cream

The effect of soy protein concentrate (0, 1.5, 3, and 4.5%) on the physical, chemical, and sensory properties of strawberry flavored (0, 0.01 and 0.02%) ice cream samples was examined. All samples were analyzed for pH, titratable acidity, total solids, nitrogen, fat, ash, overrun, viscosity, meltdown, Hunter L-, a-, b- values, flavor, body and texture, and appearance. Substituting soy protein concentrate (SPC) in ice cream formula for non-fat dry milk (NFDM) positively influenced the nitrogen content, viscosity values, and melting and appearance properties of the ice cream samples while overrun values and flavor scores were negatively affected. SPC could be incorporated into the ice cream formula in the range of 1.5–3% devoid of significantly diminishing the physical, chemical, and sensory properties.     

Production of whey protein isolate hydrolysate fractions with enriched ACE-inhibitory activity

A study on the enrichment of angiotensin-converting enzyme (ACE) inhibitory activity in whey protein isolate (WPI) hydrolysate fractions is presented. A previously identified low molecular mass fraction (1 kDa permeate) of an enzymatically hydrolysed heat-treated WPI with elevated ACE-inhibition (IC₅₀ = 0.23 g L⁻¹) was subjected to cascade membrane ultrafiltration (UF) and diafiltration steps at lab-scale. Assaying for ACE-inhibition revealed that the 1 kDa retentate demonstrated the highest ACE-inhibitory activity (IC₅₀ = 0.17 g L⁻¹). Isoelectric focussing (IEF) of the hydrolysate fraction further increased ACE-inhibition in fractions collected within the pH range 6.1–6.6. Overall, both UF and IEF enriched the ACE inhibitory activity in the original fraction by ∼52%, demonstrating the potential for enrichment of bio-functional activities in enzymatic hydrolysates of whey proteins.     

Impact of disperse microstructure on rheology and quality aspects of ice cream

Oscillatory thermo-rheometry (OTR) was used to correlate rheological properties with the microstructure and quality characteristics of ice cream. In a rotational rheometer (plate-plate geometry) the rheological behavior of ice cream was studied, performing oscillatory measurements at low deformation amplitudes for three different temperature ranges corresponding to important consumer properties of ice cream.The ice crystal microstructure determined the rigidity and “scoopability” of ice cream at low temperatures (−20°C to −10°C). The higher the overrun and the smaller the connectivity of ice crystals, the smaller were the measured storage and loss moduli G′ and G″.The slope of the variations in G′ and G″ with temperature in the range between −10°C and 0°C were correlated with the sensory impression of coldness. Decreasing overrun levels led to steeper slopes and correspondingly to a more pronounced impression of coldness.The microstructures of air and fat phases had also a significant impact on the rheology and the sensorial “creaminess” of ice cream especially in the molten state (0-10°C). With increasing overrun levels, ice cream showed increasing storage and loss moduli at temperatures higher than 0°C. Smaller air bubble sizes and increased fat globule aggregation in low temperature extruded (LTE) ice cream led to higher values of G″ in comparison to conventionally hardened (Freezer) ice cream.Sensorial studies demonstrated a close correlation between loss moduli G″ measured in the OTR-test and the ice cream quality parameters scoopability and creaminess. The improved scoopability and increased creaminess of LTE ice cream in comparison to Freezer ice cream was measured quantitatively by a decrease of G″ at a temperature of −15°C and a increase of G″ for ice cream in the molten state.     

High hydrostatic pressure modification of whey protein concentrate for use in low-fat whipping cream improves foaming properties

Whey is the inevitable by-product of cheese production. Whey can be incorporated into a variety of foods, but little has been done to investigate its suitability in whipping cream. The objective of this work was to evaluate the foaming properties of selected low-fat whipping cream formulations containing whey protein concentrate (WPC) that did or did not undergo high hydrostatic pressure (HHP) treatment. Fresh whey was concentrated by ultrafiltration, pasteurized, and standardized to 8.23% total solids and treated with HHP at 300 MPa for 15 min. Viscosity, overrun, and foam stability were determined to assess foaming properties. Sensory evaluation was conducted with 57 panelists using a duo-trio difference test. The optimal whipping time for the selected formulations was 3 min. Whipping cream containing untreated WPC and HHP-treated WPC resulted in greater overrun and foam stability than the control whipping cream without WPC. Panelists distinguished a difference between whipping cream containing untreated WPC and whipping cream containing HHP-treated WPC. High hydrostatic pressure-treated WPC can improve the foaming properties of low-fat whipping cream, which may justify expansion of the use of whey in whipping cream and application of HHP technology in the dairy industry.     

Impact of silkworm pupae (Bombyx mori) powder on cream foaming,ice cream properties and palatability

Food fortification with edible insects can offer high nutritional values, improve consumer acceptance and sustainability of resources. This study elucidates the ramifications of silkworm pupae flour (SWF), i.e. dried and pulverized, on the rheological, textural, and sensorial properties of whipping and ice-cream. Results indicate SWF supplementation attenuates cream overrun (p < 0.05) with an observed viscosity increase. Contrary, SWF addition reduced (p < 0.05) separation of foam implying a shelf-life improvement. SWF enriched ice-cream exhibited altered texture attributes (hardness and adhesiveness) especially when using more than 1% (w/w) SWF. In addition, a notable effect on product color was registered which explains the reduced visual appeal of ice-creams containing 2.5% and 4% (w/w) SWF. Moreover, an untrained tasting panel (mean age: 28.6 ± 8.6) reported a strong aftertaste. Overall, this study concludes that SWF at concentrations of ≤1% (w/w) can enhance ice-cream techno-functional properties while maintaining palatability.Industrial relevanceEdible insects are a promising, cost-effective and highly sustainable food resource for proteins and other macro and micro-nutrients. Besides their nutritional advantages, they possess potential techno-functional properties that persist during processing operations and comply with various food matrices. This study offers an original use of bombyx Mori powder, to foam applications, like whipped cream and ice cream. Although not devoid of a on ice cream sensorial attributes, it is still palatable as ascertained by a tasting panel of 40 adult volunteers.     

Using spray-dried sugar beet molasses in ice cream as a novel bulking agent

In this study, it is aimed to investigate and evaluate the use of molasses which is a by-product of sugar production as a novel bulking agent in ice cream as a sugar replacer. Sugar beet molasses (75%) and 12 DE maltodextrin (25%) were converted into powder form by spray drying. Spray-dried sugar beet molasses (SDSM) was then used as a substitute of sugar in different ratios (0:100, 25:75, 50:50, 75:25 and 100:0) in the ice cream products. The increased amount of SDSM decreased the overrun, L*, whiteness index (WI) and melting behaviours and increased a*, b*, total phenolic content, consistency and viscosity. Meanwhile, thermal properties have not been affected by the use of SDSM (P < 0.05). The sensory findings have been particularly interesting especially when replacing above 50% sugar with SDSM, aroma, flavour and general acceptability decrease. According to the results of this study, substituting 25% of total sugar with SDSM as a bulking agent can decrease cost of the product and improve total phenolic content and some quality parameters without compromising sensorial properties.     

Preparation and evaluation of low‐calorie functional ice cream containing inulin,lactulose and Bifidobacterium lactis

This study was aimed to investigate the effects of replacing 5% fat and sugar by inulin and lactulose, respectively, on the survival of Bifidobacterium lactis and physicochemical and sensorial characteristics of the ice cream. Total solids, pH, melting rate and sensory scores of low‐fat and/or low‐sugar ice cream samples did not differ significantly from the control. Overrun and hardness of low‐fat samples were significantly higher than that of the control group (P < 0.01). The viable counts of B. lactis in the low‐sugar synbiotic ice creams were significantly lower than that of other groups at the end of 90‐day storage (P < 0.01).     

Producing ice cream using a substantial amount of juice from kiwifruit with green,gold or red flesh

Ice cream prepared using a substantial amount of juice from kiwifruit with green, gold or red flesh may have consumer appeal, through the combination of kiwifruit's unique color, natural flavor and health-promoting constituents. The aqueous fractions from purees of kiwifruit with green, gold and red flesh (AFKWs) were added at 49% v/v to a basic low-fat ice cream mix that contained no commercial flavoring and coloring agents. The resultant ice creams were subjected to comparative product evaluation (e.g. overrun, melting behavior and rheological properties) and chemical analyses of bioactives (e.g. total extractable polyphenol content (TEPC), vitamin C, antioxidant capacity, polyphenol (PP) and carotenoid composition). Results revealed that both the pH pre-adjustment and pre-heating of the AFKW played critical roles in ice cream making. The ice creams retained the PP and vitamin C contents as well as natural color flavor of the kiwifruit used. The rheological properties of all ice creams showed non-Newtonian flow behavior, and the storage modulus G′ decreased in the same pattern following the order of green > gold > red. The melting rate, overrun and vitamin C content of the ice cream with green AFKW were the fastest, lowest and least, respectively. The TEPC and antioxidant capacity in the ice cream with red AFKW were the highest. The amounts of PPs and vitamin C were encouragingly high. Health beneficial compounds, dimethyl-caffeic acid hexoside, caffeic acid derivatives, protocatechuic acid, syringic acid, salicylic acid/ο-coumaric acid, lutein and beta-carotene, were detected in the final products. Thus, there are commercial possibilities for using AFKW which should be further evaluated.