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

Mapping the Meltdown Behavior of Frozen Dairy Desserts

The meltdown test is an efficient tool widely and commonly used to characterize structural changes in frozen desserts resulting from different ingredients and processing conditions. The meltdown is commonly determined by a gravimetric test, and it is used to obtain the onset (Mon), rate (Mrate), and maximum (MMax) meltdown. However, these parameters are calculated ambiguously due to the inconsistency in the methodology. This work aims at modeling the meltdown curves (weight vs time) of different commercial samples (36 commercial samples). Samples of commercial frozen desserts (40-60 g) was placed on a 304 stainless wire cloth (1.50 mm opening size and 52% open area) suspended about 15 cm above of an analytical balance, and the dripped portion of the melted ice cream was continuously recorded throughout the duration of the test. The meltdown test was conducted at room temperature. Each meltdown test generated more between 3000 to 4000 data points and was modeled using 4 equations: The logistic model, the Gompertz model, the Richard model, and the Hill model. All the meltdown curves were sigmoidal in shape, regardless of the type of frozen dessert. The experimental meltdown curves were adequately represented by the Logistic model, judging by several criteria (R2 = 0.999, adjusted RAdj2 = 0.999, Akaike probability = 6582, and F-value = 1.88 × 106). Thus, the Logistic model was shown to be an effective tool for predicting the meltdown curves of frozen desserts, and it can be used to define unambiguously the onset, rate, and maximum meltdown. Moreover, a dimensionless response (meltdown behavior, MBe) that combines Mon, Mrate, and MMax was developed and used for mapping the meltdown of different commercial frozen desserts.

Partition of milk phospholipids during ice cream manufacturing

The distribution of phospholipids (PL) within the fat and serum phase of ice cream manufacturing was evaluated through partition coefficients (KPL) after mixing, pasteurization, freezing, and hardening. Ice creams containing about 40.41 ± 3.45 (± standard deviation; control formulation) and 112.29 ± 9.06 (enriched PL formulation) mg of PL per g of fat were formulated with nonfat dry milk and β-serum, respectively. Overall, the KPL were lower than 1, indicating that the PL were predominantly found in the fat phase, and only a small amount was left in the serum and sediment. Confocal micrographs visually confirmed this generalization. The addition of PL significantly increased the viscosity of the mixes between 4- and 9-fold, depending on the shear rate. Additionally, mixes containing high PL exhibited higher yield stress than those formulated with low PL (0.15 ± 0.09 and 0.016 ± 0.08 Pa, respectively). Ice creams with high PL delayed the onset of meltdown and exhibited a slower rate of a meltdown than low-PL ice creams (18.53 ± 0.57 and 14.83 ± 0.85 min, and 1.01 ± 0.05 and 0.71 ± 0.04% min-1, respectively). This study provides useful guidelines for manufacturing ice cream enriched in milk PL. Additionally, the use of β-serum, a byproduct stream, as a source of PL is illustrated. The development will require studying the sensorial description of the product as well as consumer acceptance.

Corn cob hemicelluloses as stabilizer for ice recrystallization inhibition in ice cream

Food stabilizers, such as guar gum and locust bean gum (LBG), are often added to ice cream to improve its texture and to combat its main shelf-life concern - ice recrystallization. Recently these gums have become increasingly expensive due to the limited supplies. In this study, holocellulose nanocrystals (holoCNCs) and hemicelluloses (hemiCs) were prepared from readily available corn cobs and tested for ice recrystallization inhibition (IRI) activities in the 25.0 % sucrose solution and ice cream mixes (ICMs). In the sucrose solution, holoCNCs were not IRI active at a concentration of 0.5 %, but hemiCs demonstrated a good IRI activity, even at 0.1 %. In the ICMs, the IRI activity of hemiCs was better than those of guar gum and LBG at a concentration of 0.2 %. Adding 0.2-0.5 % hemiCs had no negative influences on the physicochemical properties of ICMs and ice cream, including viscosity profile, particle size distribution, overrun, hardness, and meltdown rate. These research findings demonstrated corn cob hemiCs' potential as a more sustainable ice cream stabilizer.

Shrinkage in frozen desserts

Shrinkage is a well-documented defect in frozen desserts, yet the root causes and mechanisms remain unknown. Characterized by the loss of volume during storage, shrinkage arose during the mid-twentieth century as production of frozen desserts grew to accommodate a larger market. Early research found that shrinkage was promoted by high protein, solids, and overrun, as well as postproduction factors such as fluctuations in external temperature and pressure. Rather than approaching shrinkage as a cause-and-effect defect as previous approaches have, we employ a physicochemical approach to characterize and understand shrinkage as collapse of the frozen foam caused by destabilization of the dispersed air phase. The interfacial composition and physical properties, as well as the kinetic stability of air cells within the frozen matrix ultimately affect product susceptibility to shrinkage. The mechanism of shrinkage remains unknown, as frozen desserts are highly complex, but is rooted in the physicochemical properties of the frozen foam. Functional ingredients and processing methods that optimize the formation and stabilization of the frozen foam are essential to preventing shrinkage in frozen desserts.

A Mathematical Modeling of Freezing Process in the Batch Production of Ice Cream

This study deals with the mathematical modeling of crystallization kinetics occurring during batch production of the ice cream. The temperature decrease was recorded in-situ through a computerized wireless system. A robust pattern-recognition algorithm of the experimental cooling curves was developed to determine the initial freezing point. The theoretical freezing point was used to calibrate the whole time-temperature profile. Finally, a modified Gompertz's function was used to describe the main steps of crystallization kinetics. Derivative analysis of the Gompertz's function allowed to determine the time-temperature physical markers of dynamic nucleation, ice crystal growth and air whipping. Composition and freezing properties were used as input variables in multivariate analysis to classification purposes of the ice cream mixtures as a function of their ability to produce high-quality ice cream. The numerical analysis of the whole cooling curve was used to build predictive models of the ice cream quality indices.

Use of hydrocolloids as cryoprotectant for frozen foods

Freezing is one of the widely used preservation methods to preserve the quality of food products but it also results in deteriorative changes in textural properties of food which in turn affects its marketability. Different foodstuffs undergo different types of changes in texture, taste and overall acceptability upon freezing and subsequent frozen storage. Freezing and thawing of pre-cut or whole fruits and vegetables causes many deleterious effects including texture and drip losses. The major problem in stability of ice-cream is re-crystallization phenomena which happens due to temperature fluctuations during storage and finally impairs the quality of ice-cream. Frozen storage for longer periods causes rubbery texture in meat and fish products. To overcome these problems, hydrocolloids which are polysaccharides of high molecular weight, are used in numerous food applications involving gelling, thickening, stabilizing, emulsifying etc. They could improve the rheological and textural characteristics of food systems by changing the viscosity. They play a major role in retaining texture of fruits and vegetables after freezing. They provide thermodynamic stability to ice cream to control the process of re-crystallization. Hydrocolloids find application in frozen surimi, minced fish, and meat products due to their water-binding ability. They are also added to frozen bakery products to improve shelf-stability by retaining sufficient moisture and retarding staling. Various hydrocolloids impart different cryoprotective effects to food products depending upon their solubility, water-holding capacity, rheological properties, and synergistic effect with other ingredients during freezing and frozen storage.

Effect of okra cell wall and polysaccharide on physical properties and stability of ice cream

Stabilizers are used in ice cream to increase mix viscosity, promote smooth texture, and improve frozen stability. In this study, the effects of varying concentrations (0.00%, 0.15%, 0.30%, and 0.45%) of okra cell wall (OKW) and its corresponding water-soluble polysaccharide (OKP) on the physical characteristics of ice cream were determined. Ice cream mix viscosity was measured as well as overrun, meltdown, and consumer acceptability. Ice recrystallization was determined after ice cream was subjected to temperature cycling in the range of -10 to -20 °C for 10 cycles. Mix viscosity increased significantly as the concentrations of OKW and OKP increased. The addition of either OKW or OKP at 0.15% to 0.45% significantly improved the melting resistance of ice cream. OKW and OKP at 0.15% did not affect sensory perception score for flavor, texture, and overall liking of the ice cream. OKW and OKP (0.15%) reduced ice crystal growth to 107% and 87%, respectively, as compared to 132% for the control (0.00%). Thus, our results suggested the potential use of OKW and OKP at 0.15% as a stabilizer to control ice cream quality and retard ice recrystallization. OKP, however, at 0.15% exhibited greater effect on viscosity increase and on ice recrystallization inhibition than OKW.