Formulated with varied moisture contents (10–12%), dextrose equivalence (DE) of corn syrups (28, 42, 63 DE), and the concentrations of mono-and diglycerides (MDG, 0–2%), 9 caramel samples were ...compared in terms of rheology, surface energies, hardness, and stickiness. Results indicated that moisture and DE significantly altered the rheology of the caramel matrix, whereas MDG reduced the surface energies. Results from a peel test showed that the adhesive forces between caramel and a packaging material followed a bell-shaped trend with G’ and G” of the caramels and decreased with the surface energies of both the caramels and the materials. On the other hand, the caramel structure was sensitive to pressure. Increased penetration strain resulted in structural collapse, which reduced cohesion while facilitating adhesion. At 50% strain, the pressure-induced adhesive forces decreased with moisture content, DE of corn syrup, and MDG concentration. MDG (>1%) in caramel was an effective anti-sticking agent, which reduced both peel and pressure-induced adhesion.
•Mono- and diglycerides (MDG) reduced the surface energy of caramel.•Caramel moisture and DE of corn syrup affected the rheology but not surface energy.•Stickiness of caramel changed with both rheology and surface energy.•MDG reduced both surface stickiness and pressure-induced stickiness.•Caramel hardness and pressure-induced stickiness were positively correlated.
In the dairy industry, crystallization is an important separation process used in the refining of lactose from whey solutions. In the refining operation, lactose crystals are separated from the whey ...solution through nucleation, growth, and/or aggregation. The rate of crystallization is determined by the combined effect of crystallizer design, processing parameters, and impurities on the kinetics of the process. This review summarizes studies on lactose crystallization, including the mechanism, theory of crystallization, and the impact of various factors affecting the crystallization kinetics. In addition, an overview of the industrial crystallization operation highlights the problems faced by the lactose manufacturer. The approaches that are beneficial to the lactose manufacturer for process optimization or improvement are summarized in this review. Over the years, much knowledge has been acquired through extensive research. However, the industrial crystallization process is still far from optimized. Therefore, future effort should focus on transferring the new knowledge and technology to the dairy industry.
This study aimed to investigate the crystal network of bulk milk fat fractions and the partial coalescence, and the rheological properties of their oil-in-water (O/W) emulsions. Different milk fat ...fraction model systems were compared for their physicochemical properties, crystallization kinetics, and fat crystal networks across a range of temperatures. The extent of partial coalescence and rheological properties of the O/W emulsion prepared by different milk fat fractions were further analyzed. The results demonstrated that the ratio between saturated fatty acids (SFA) and unsaturated fatty acids and triacylglycerides (TAG) influenced the melting thermal behaviors, solid fat contents (SFC), and crystal networks of various milk fat fractions, which in turn influenced the partial coalescence and rheological characteristics of their O/W emulsions. Moreover, an excellent fit of the trend line confirmed that hardness increased exponentially with SFC. Trisaturated TAG in fractions with high melting points (HMF) such as milk fat fraction MF45, whose clarification temperature was 45°C, enriched long-chain SFA (saturated:unsaturated fatty acid = 2.2:1). We found that MF45 achieved higher SFC and hardness in the range of 0 to 40°C and, ultimately, formed a well-defined microstructural network with thick, rod-like crystals. Further, TAG in fractions with low melting points (LMF) such as MF10, whose clarification temperature was 10°C, were enriched with short-chain and unsaturated fatty acids (saturated:unsaturated fatty acid = 1.5:1), and a disordered crystal network in MF10, composed of randomly arranged, translucent platelets, was detected. Although fat globules of HMF and LMF were stabilized against coalescence, this could be attributed to a variety of mechanisms involving SFC, liquid fat, protective film around the fat globule, and minor lipids. According to the rheological profiles, all O/W emulsions exhibited weak viscoelastic “gel-like” structures storage modulus (G′) > loss modulus (Gʺ) over most of the measured range. The G′ values and apparent viscosity of HMF were greater than those of other fractions, indicating that the large and rigid crystals strengthen the networks more effectively.
Stickinessis an inherent textural property in many sugar‐rich foods, which can be problematic to the processing of confectionery products. The adhesion between foods and contact surfaces during ...processing and consumption has not been well understood in academia or industry. The theories of adhesion were discovered by scientists in the adhesive field of study, some of which can explain the stickiness phenomenon of confections. This work reviewed these theories in the context of sugar‐rich foods, followed by a survey on the sensory and instrumental analyses of stickiness. Furthermore, the contributions of ingredients, temperature, compression, and contact surfaces to sugar‐rich food adhesion are highlighted.
Advances in food crystallization Hartel, Richard W
Annual review of food science and technology,
02/2013, Volume:
4
Journal Article
Peer reviewed
Crystals often play an important role in food product quality and shelf life. Controlling crystallization to obtain the desired crystal content, size distribution, shape, and polymorph is key to ...manufacturing products with desired functionality and shelf life. Technical developments in the field have improved the tools with which we study and characterize crystals in foods. These developments also help our understanding of the physico-chemical phenomena that govern crystallization and improve our ability to control it during processing and storage. In this review, some of the more important recent developments in measuring and controlling crystallization are discussed.
Ice cream is a multiphase frozen food containing ice crystals, air cells, fat globules, and partially coalesced fat globule clusters dispersed in an unfrozen serum phase (sugars, proteins, and ...stabilizers). This microstructure is responsible for ice cream's melting characteristics. By varying both formulation (emulsifier content and overrun) and processing conditions (dasher speed), the effects of different microstructural elements, particularly air cells and fat globule clusters, on ice cream melt‐down properties were studied.
Factors that caused an increase in shear stress within the freezer, namely increasing dasher speed and overrun, caused a decrease in air cell size and an increase in extent of fat destabilization. Increasing emulsifier content, especially of polysorbate 80, caused an increase in extent of fat destabilization. Both overrun and fat destabilization influenced drip‐through rates. Ice creams with a combination of low overrun and low fat destabilization had the highest drip‐through rates. Further, the amount of remnant foam left on the screen increased with reduced drip‐through rates. These results provide a better understanding of the effects of microstructure components and their interactions on drip‐through rate.
Practical Applications
Manipulating operating and formulation parameters in ice cream manufacture influences the microstructure (air cells, ice crystals, and fat globule clusters). This work provides guidance on which parameters have most effect on air cell size and fat globule cluster formation. Further, the structural characteristics that reduce melt‐down rate were determined. Ice cream manufacturers will use these results to tailor their products for the desired quality attributes.
This study aims at exploring ice cream meltdown behavior by changing the levels of stabilizer (ST), polysorbate 80 (PS80), and overrun (OR). By adjusting the formulation of ice cream, the degree of ...fat destabilization (FD), mix viscosity (MV), and overrun can be controlled within a certain range, which in turn presents different meltdown behaviors for study. In addition to the drip‐through test, the shape of ice cream as it melts was recorded as height change to further investigate ice cream meltdown. Mix viscosity (at 50 s−1) and fat destabilization were found to have a significant effect not only on drip‐through rate, but also the induction time, final weight of the drip‐through part, height‐change rate, and final height of melted ice cream. On the other side, overrun was found only to have an effect on meltdown when no stabilizers were added. These results indicate serum phase viscosity (mix viscosity) and fat destabilization are important parameters to describe ice cream meltdown. Besides, the entire ice cream meltdown curve and height collapse curve provide important information on ice cream meltdown behavior.
Practical application
A new direction of analysis of ice cream meltdown behavior is provided in this study. The induction time, the final drip‐through weight, and the height change during the meltdown process were found to be the indicators on the influence of microstructure on ice cream meltdown behavior for the future study.
This research delves into the Maillard reaction (MR) in high-solid gelatin-saccharide mixtures consisting of 8% and 72% of allulose, fructose, or fructo-oligosaccharides, which were subjected to ...varied duration (0–60min) of thermal processing prior to gelation. Physicochemical properties of the gels, including color, chemical composition, protein crosslinking, mechanical strength, in-vitro digestibility and antioxidant activities, were characterized. At pH ∼5.5 and intermediate water activities (0.6–0.7), fast browning was observed through sugar degradation and sugar-amine interactions, which were intensified by prolonged heating. The MR reactivity of saccharides followed: AL > FRU > FOS. Characteristic products (MRPs, e.g., α-dicarbonyls, 5-hydroxymethylfurfural, and advanced glycation end products) were identified, with the spectra of MRPs varying significantly between monosaccharides and oligosaccharides. The MR-induced protein glycation and crosslinking exhibited certain negative impacts on the gel strength and in-vitro protein digestibility. Furthermore, all gelatin-saccharide mixtures exhibited augmented antioxidant properties, with the gelatin-AL mixtures displaying the highest free radical scavenging rates.
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•Maillard reaction (MR) in high-solid gelatin-saccharide mixed gels were characterized.•Sugar degradation prevailed over sugar-amine interactions during thermal processing.•Harmful products (α-DC, 5-HMF, and AGEs) were quantified in confectionery gels.•MR-induced protein crosslinking led to reduced gelation and protein digestion.•MR enhanced antioxidant activity of confectionery gels, especially with allulose.
Although the ice phase greatly influences the properties of ice cream, other structural components also affect its rheological behavior, particularly after melting. In this study, mix viscosity ...(serum phase viscosity), extent of fat destabilization (FD), and overrun were manipulated to produce different microstructures. The effects of these structural components were evaluated on the rheological properties of the ice creams and melted ice creams. In oscillatory thermorheometry, mix viscosity and then overrun, influenced G’ and tanδ below −10 °C. When ice phase decreased (between −10 and −2.7 °C), mix viscosity had reduced effects, but continued to strongly affect G’ and tanδ, followed by FD, and with lower effects from overrun. When the ice phase was completely melted at 0 °C, FD had most influence on G’ and tanδ, followed by overrun, and with lower effects from mix viscosity. In creep/recovery test, six‐element model described well creep behavior of melted ice cream at 0 °C. Viscous behavior at lower shear rate (η0 0 °C) was most influenced by mix viscosity, followed by FD, and lower overrun effects. In stress growth measurement, transient behavior, represented by σY 0 °C, of melted matrix at 0 °C was most influenced by FD, followed by mix viscosity, with lower overrun effects. In flow ramp measurement, Hysteresis Area was most affected by mix viscosity, followed by overrun, and with lower FD effects. Moreover, correlation between Hyst 0 °C and tanδ Peak suggested that structure formation affected the magnitude of tanδ Peak. These results document the importance of microstructure on properties of melted ice cream.
Practical Application
The understanding of how structural components, such as mix viscosity, fat destabilization, and overrun, affect the ice cream matrix can help manufacturers to control its rheological behavior. The influence of these structural components on the G’, tanδ, η0 0 °C, σY 0 °C, and Hyst 0 °C can be also used to understand the structural rearrangements that occur in meltdown tests and sensory analyses for future studies. Therefore, elucidation of these mechanisms on the rheological properties can directly assist in quality control and new product development in the ice cream industry.
Gummies are gelatin-based confectionery gel products where the sweeteners play vital roles in the product texture. This study focused on the impacts of sweeteners, which make up ~70–80% of the total ...solids, on the sol properties, gelling, and melting behaviors of gelatin (4–6%) gels. Gelling and melting properties of gelatin solutions with and without sweeteners (sucrose and glucose syrup) were characterized with rheology and differential scanning calorimetry, while the final gel texture and surface properties were analyzed with texture analyzer and tensiometer. In contrast to the plain systems without sweeteners, which gelled at around 22 °C and melted at 35 °C, the high-sweetener systems exhibited coil-to-helix transition at a higher temperature level, and the subsequent sol-gel transition depended greatly on the bulk viscosity. Below the sucrose-syrup level of 75.9%, the transition was observed at 34–43 °C; higher levels of saccharides postponed or inhibited the transition. The internal interactions of high-sugar gels were considerably weaker than the plain gels, suggesting smaller and more dispersed junction zones. The quantities of melting enthalpy and internal interactions increased with gelatin concentration but decreased with sucrose-syrup level, due to the high viscosity. Gel surfaces were generally hydrophobic (non-polar) except for the 4% gelatin gels, whose surface polarity increased with sugar level. Gel hardness and tackiness increased with gelatin concentration but did not change significantly with moisture/sugar content at 5–6% gelatin.
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•Gelling and melting behaviors of plain and high-sugar gelatin gels were compared.•Renaturation rate decreased with the sucrose-syrup levels due to high viscosity.•Rheology and texture of gels were governed by both gelation and glass transition.•Gelatin gels had hydrophobic surfaces except for high-sugar gels with 4% gelatin.•Surface tackiness was strongly correlated with the hardness of the gels.
