Technological and sensorial properties of liquid nitrogen ice cream enriched with protein from brewing waste (trub)

Debittered trub (brewing waste) is an important source of protein source (70.26%). Trub and whey protein were used for 5% protein enrichment of ice cream frozen by liquid nitrogen. Three formulations were elaborated: ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Chemical composition, rheological properties, texture, overrun, melting rate, scanning electron microscopy and a sensorial test were performed. Results showed that ICT presented a higher viscosity, obtained on the upward curve up to 6.76 Pa s⁻¹, consistency index (22.96 (Pa s⁻¹)ⁿ), hysteresis area (140.40 mPa s⁻¹) and hardness (31113.33 g) but a lower melting rate (0.38 g min⁻¹), overrun (13.92%) and sensorial acceptability than the other formulations. The addition of trub debittered for protein enrichment improved ice cream properties and demonstrated that it could be used as a food ingredient.     

Susceptibility of an industrial α-lactalbumin concentrate to cross-linking by microbial transglutaminase

The susceptibility of an industrial α-lactalbumin concentrate to cross-linking with a microbial transglutaminase from Streptoverticillium mobaraense was investigated. At a protein concentration of 0.5% w v⁻¹, the maximum cross-linking was observed at 50°C, pH 5 and at 5 h of incubation time. Results from sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis showed that most of the monomeric form of α-lactalbumin was converted to polymers too large to move into the gel matrix. Addition of ethylenediamine tetraacetic acid or SDS prior to the incubation of protein–enzyme mixture, further enhanced the transglutaminase reaction with the industrial α-lactalbumin. Results from reverse phase chromatography indicated that cross-linking caused a broadening of the α-lactalbumin peak with little change in the average hydrophobicity of the protein. In contrast to the reported results on pure α-lactalbumin, the industrial α-lactalbumin concentrate showed considerable cross-linking with transglutaminase even without the reduction of the disulphide bonds. This difference was attributed to the partially unfolded secondary structures in the industrial α-lactalbumin concentrate.     

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).     

Improvement of canola protein gelation properties through enzymatic modification with transglutaminase

Enzymatic modification with transglutaminase (TG) was used to enhance the gelation of canola protein isolate (CPI) and thus improve its potential as a food ingredient. The effects of CPI concentration, TG concentration, treatment temperature and treatment time on CPI gelation properties were evaluated. A texture analyzer, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscopy were used to characterize the resulting networks. The protein concentration, amount of TG, and treatment temperature were found to significantly impact gel strength. It was found that gelation can be improved by increasing the amounts of protein and TG and by keeping the treatment temperature close to 40 °C. SDS-PAGE showed that cross-linking of subunits occurred through TG treatment thus helping to explain the increase in gel strength observed during texture analysis. Micrographs further corroborated the trends noted during rheological studies.     

Milk colloidal system as a reaction medium and carrier for the natural blue colorant obtained from the cross-linking between genipin and milk proteins

A promising natural blue colorant was obtained from the cross-linking between genipin and milk proteins. Milk was simultaneously used to extract genipin from the unripe genipap (Genipa americana L.) and evaluated as a reaction medium and carrier for the novel blue colorant. The effects of the milk composition (skimmed, semi-skimmed, and whole) on the kinetic of blue color formation in the colorant-loaded milk samples during their cold storage time for 96 h were evaluated using their color parameters and free-genipin content. The reaction between milk proteins and genipin were evaluated by FTIR spectroscopy. In addition, the blue colorant-loaded milk samples were characterized according to their droplet size distribution, microstructure, and phase separation kinetics. The milk fat content influenced the genipin recovery while the milk with higher protein content contributed to obtaining a more intense blue color. Using whole milk with 3.0 g/100 g fat content favored the light scattering and, thus, a blue colorant with a more intense −b¹ and L¹ values was obtained. On the other hand, the use of skimmed milk with 0.5 g/100 g fat content resulted in more consumption of genipin due to its more protein content for the reaction of blue color compounds formation. Thus, a more intense and darker blue coloration was observed with lower light scattering. The milk composition did not modify the phase separation kinetics of the blue colorant-loaded milk. Therefore, our results have demonstrated that the milk was a suitable medium for the reaction of blue color formation and also a good blue compounds carrier.Industrial relevanceConsumer demands for natural colorants have increased in the last years.Thus, the new food industry challenge is to develop novel healthy, safe and high-quality food products based on natural colorants. Currently, the colorant market does not have still available a natural blue colorant. Therefore, the development of a novel natural blue colorant from plant material could meet this worldwide demand increasing the added value of many products such as ice cream, dairy beverages, and candies.     

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.     

谷氨酰胺转氨酶对全麦面团特性及微观结构的影响

利用混合实验仪、质构仪、动态流变仪、扫描电镜、激光共聚焦显微镜和电泳仪等,研究不同添加量谷氨酰胺转氨酶（glutamine transaminase,TG）对全麦面团的混合特性、拉伸特性、流变特性、微观结构和蛋白质变化的影响。结果表明,随着TG添加量的增加,全麦面团的吸水率下降,面团形成时间和稳定时间先增加后降低,峰值黏度升高,回生值降低;面团拉伸强度先升高后降低;随着TG添加量的增加以及酶反应时间的延长,全麦面团的弹性模量（G’）和黏性模量（G”）上升,损耗角正切值（tanδ）降低,当TG添加量＞2.4 U/g、作用时间＞120 min时,易造成蛋白质过量交联及聚集,全麦面团的综合黏弹性下降。扫描电镜与激光共聚焦显微镜结果显示,TG的添加使得面团微观结构紧密连续,面筋结构得到明显改善;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果显示,TG诱导蛋白质分子交联形成大分子聚集体。     

Application of cold- and heat-adapted Lactobacillus acidophilus in the manufacture of ice cream

Manufacture of ice cream using cold- and heat-adapted Lactobacillus acidophilus was studied. Temperature–time combinations at 4 °C for 18 h and at 45 °C for 15 min were set as the adaptation conditions for below and above the optimum growth temperature (37 °C), respectively. Ice cream was produced by two different methods: method 1, ice cream mix was fermented with cold- and heat-adapted L. acidophilus prior to freezing; method 2, cold- and heat-adapted L. acidophilus was added to ice cream mix but the mix was not fermented with L. acidophilus prior to freezing. The lowest reduction ratio was found in the samples produced by using method 1 and cold-adapted L. acidophilus, adapted at 4 °C for 18 h. L. acidophilus survived at the required levels (>10⁶ cfu g⁻¹), with or without an adaptation. The adaptation conditions improved stability of L. acidophilus in the samples, but the magnitude of improvement was small.     

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.     

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.     

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.     

Comparison of the effects of adding microbial transglutaminase to milk and ice cream mixture on the properties of ice cream

In this study, the effect of recombinant microbial transglutaminase enzyme on the physicochemical properties of ice cream produced by two different methods was investigated. For this purpose, different enzyme units (2, 4 and 6 U/g milk protein) were applied to both ice cream mixture and milk. While with the first method, a 10% increase in the overrun value of ice cream samples was observed, a 7% increase was obtained by the second method. All ice cream samples exhibited pseudoplastic behaviour. This study indicated that  transglutaminase concentration is an important factor in terms of improving the physicochemical properties of ice cream.     

Transglutaminase-induced cross-linking and glucosamine conjugation in soybean protein isolates and its impacts on some functional properties of the products

In the presented work, we exploited microbial transglutaminase as a biocatalyst and glucosamine as an acyl acceptor to modify soybean protein isolates (SPI) by cross-linking and glucosamine conjugation and evaluated some functional properties of the modified product prepared. Electrophoretic studies revealed that transglutaminase-induced cross-linking and glucosamine conjugation occurred simultaneously during modification reaction, and some polymers of glycoproteins with higher molecular weights were formed in the modified product. HPLC analysis demonstrated that about 3.3 mol of glucosamine could be conjugated to 1 mol of SPI, under the preparation conditions as following: SPI concentration of 3% (w/v), acyl donor in SPI/glucosamine acceptor molar ratio of 1:3, transglutaminase addition level of 10 U g⁻¹ proteins, reaction temperature of 37 °C, and reaction time of 6 h. Compared to SPI and transglutaminase-induced cross-linked SPI, the modified product with glucosamine conjugation about 3.3 mol mol⁻¹ SPI clearly exhibited lower surface hydrophobicity, better interfacial properties (especially in emulsion and foaming stability), markedly increased apparent viscosity in the prepared dispersion, and higher enzymatic digestibility in vitro. Our results showed that this modification technique might have the potential as an effective approach to improve the functional properties of SPI.     

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 delbrueckii UFV H2b20 in ice cream produced with different fat levels and after submission to stress acid and bile salts

The survival of Lactobacillus delbrueckii UFV H2b20 in three ice cream formulations (low fat, fat free and high fat) was evaluated after the processing and storage at ?16 °C. The survival of L. delbrueckii UFV H2b20 was not significantly affected (P > 0.05) in three ice cream formulations after processing. The same result was observed during storage for 40 days at ?16 °C. Cells of L. delbrueckii UFV H2b20 incorporated in three ice cream formulation survived when exposed to acid stress and bile salts. The results demonstrate that L. delbrueckii UFV H2b20 has potential for being used in ice cream and capacity to resist acid stress and to grow in the presence of bile salts. This demonstrates that reduction of fat in ice cream does not compromise the viability of L. delbrueckii UFV H2B20.     

Effects of storage conditions,microencapsulation and inclusion in chocolate particles on the stability of probiotic bacteria in ice cream

Three technological approaches to enhance viable counts of probiotic bacteria in ice cream were examined: post-freezing inoculation, use of a microencapsulated culture (spray-coating technology) and inclusion of cultures in chocolate or tablet particles. When a free-cell powder (FCP) of Bifidobacterium longum R0175 was added to the soft ice cream before hardening, a drop of almost 3 log cfu g⁻¹ occurred during production and storage, while it was of only 0.43 log cfu g⁻¹ for Lactobacillus rhamnosus R0011. However, inoculation with a powder of microencapsulated cells (MEP) improved stability of B. longum. The viability of probiotics was further improved when the MEP was incorporated into chocolate particles, which were subsequently blended into the ice cream. Viability losses of the FCP culture during storage at −16 °C in a household freezer having periodic defrost cycles were 10 times higher than when constantly maintained at −20 °C.     

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.     

Influence of enzymatic cross-linking on milk fat globules and emulsifying properties of milk proteins

The enzyme transglutaminase (TGase) can modify dairy protein functionality through cross-linking of proteins. This study examined the effects of TGase treatment on milk fat globules and the emulsifying properties of milk proteins. The extent of TGase-induced cross-linking of caseins increased with incubation time, with no differences between whole and skim milk. Extensive clustering of fat globules in extensively cross-linked raw whole milk occurred on homogenisation at 400 or 800 bar. Considerably less clustering of fat globules was observed when recombined milk (90 g fat L^–1) was prepared from TGase-treated skim milk and homogenised at 400 or 800 bar. TGase treatment did not affect fat globule size in cream, but prevented coalescence of fat globules therein, possibly through cross-linking of milk fat globule membrane components. TGase-induced cross-linking of milk proteins affected their emulsifying properties and may increase the stability of natural milk fat globules against coalescence.     

RHEOLOGICAL BEHAVIOR AND TIME-DEPENDENT CHARACTERIZATION OF ICE CREAM MIX WITH DIFFERENT SALEP CONTENT

The effect of salep concentration on the rheological characteristics of ice cream mixes (0.5–1.5% salep content), prepared from nonfat cow's milk and sugar, was studied using a controlled stress rheometer. The flow curves and time‐dependent flow properties of the ice cream mixes were assessed at different temperatures. The ice cream mixes’ samples showed slightly thixotropic behavior, which was reduced as the salep content decreased. The forward and backward measurements of the flow curves of ice cream mixes were modeled with the power law model. The ice cream mixes showed pseudoplastic flow behavior after destruction of the thixotropic structure. In mixes that were first presheared at a high shear rate flow properties could also be described by the power law model. The second‐order structural kinetic, first‐order stress decay and Weltman models were applied to model the time‐dependent flow properties of the ice cream mixes. Among these, the first‐order stress decay model was found to fit well the experimental data.     

Sensorial and fatty acid profile of ice cream manufactured with milk of crossbred cows fed palm oil and coconut fat

This work was carried out to study the nutritional quality of milk of cows fed palm oil (PAL) or coconut fat (COC), and the use of that milk as raw material for ice cream production. Three treatments were tested with 23 healthy cows: control (CON), PAL, and COC. The milk was collected at d 21 and 36 of the experimental diet. Proximate composition (moisture, ash, fat, protein, and carbohydrates) and fatty acid composition were evaluated on milk and ice cream, and sensorial analysis, color (lightness, green/red, and blue/yellow), overrun, and texture were evaluated on the ice cream. Fatty acids present in milk and ice cream were determined by gas chromatography. Sensory analysis results showed that the ice cream acceptability index was above 70%. No difference was observed for proximate composition in milk and ice cream. Chromatographic analysis showed an increase in saturated fatty acid concentration in CON and lower levels in PAL; polyunsaturated fatty acid concentration was higher in PAL and lower in CON, in milk and ice cream; monounsaturated fatty acid concentration in milk was higher in PAL and lower in CON but no difference was found in ice cream. Comparing n-3 content in milk and ice cream, we observed that PAL had higher levels than CON and COC. The results indicate that it is feasible to add sources of fat to the animal feed for fatty acid composition modulation of milk and ice cream.