Application of kokum (Garcinia indica) fat as cocoa butter improver in chocolate

Although cocoa butter (CB) is an ideal fat for use in chocolate, it softens with heat and is not suitable for use in warm climates. CB extenders or improvers, preferably from stearic acid‐rich fats, are good candidates to increase the heat‐resistance property of CB and chocolate. In the present investigation, one such fat, kokum, is used as an improver to increase the hardness of chocolate. Kokum fat is added in various proportions replacing CB in dark and milk chocolate formulations and its effects on rheology, hardness and triglyceride composition were studied. The results revealed that up to 5% kokum fat addition by weight of the product did not significantly affect the plastic viscosity or yield stress of milk or dark chocolate. Hardness of both dark and milk chocolate increased with increase in addition of kokum fat. The solids fat content at and above 30 °C increased with increase in level of kokum fat with CB, especially at and above 15%. These physical properties are due to increase in 2‐oleodistearin triglycerides with addition of kokum fat with CB. The results revealed that kokum fat could be used up to 5% by wt of the product to increase the heat‐resistance property of chocolate so that it can be used in warm climates. Copyright © 2004 Society of Chemical Industry     

Relations between crystallisation mechanisms and microstructure of milk fat

Using differential scanning calorimetry, synchrotron time resolve X-ray diffraction and pulsed nuclear magnetic resonance, crystallisation mechanisms of milk fat were elucidated. Under the same crystallisation conditions, the microstructure of the milk fat was analysed with confocal laser scanning microscopy and oscillatory rheology. The milk fat was cooled without agitation to 20 °C at two different cooling rates, i.e., 0.1 and 10 °C min^?1. Thereafter, the isothermal crystallisation at 20 °C was monitored. Faster cooling resulted in a two-step crystallisation, and a microstructure that comprised smaller and more uniform crystals than was the case with slower cooling. Consequently, the final texture of the faster cooled milk fat was firmer, i.e., higher complex modulus, than that of the slower cooled milk. X-ray diffraction showed that the two-step crystallisation involved a polymorphic transition from α to β′ phase. Furthermore, it was demonstrated that oscillatory rheology is very useful for detecting polymorphic transition during crystallisation of anhydrous milk fat.     

Influence of high-melting milk fat fraction on quality and fat bloom stability of chocolate

The aim of this paper was to define the optimal concentration of a high-melting milk fat fraction with a suitable precrystallization temperature time regime in order to obtain chocolate which would have satisfactory sensory characteristics and an increased fat bloom stability. The precrystallization was performed in a laboratory crystallizer, that is in a modified Brabender pharinograph, which measures the rheological characteristics of the precrystallized fluid chocolate mass with a milk fat fraction. The experiments were performed according to the factorial plan 3² (two factors on three levels). Hardness as well as solid fat content of chocolate was measured by instrumental methods. The optimal sensory quality of chocolate was achieved by adding 1–3% of the milk fat fraction and under the 25 °C precrystallization temperature. These samples of chocolate showed the highest fat bloom stability.     

Modelling tempering behaviour of dark chocolates from varying particle size distribution and fat content using response surface methodology

Central Composite Rotatable Design (CCRD) for K = 2 was used to study the combined effects of multi-stage heat exchangers for Stages 1 (14–30 °C) and 2 (12–28 °C) coolant temperatures at constant Stage 3 coolant and holding temperatures during tempering of dark chocolates using laboratory-scale mini-temperer. Quantitative data on chocolate temper index (slope) were obtained for products with varying particle size distribution (PSD) (D₉₀ of 18, 25, 35 and 50 μm) and fat (30% and 35%) content. Regression models generated using stepwise regression analyses were used to plot response surface curves, to study the tempering behaviour of products. The results showed that both Stage 1 and Stage 2 coolant temperatures had significant linear and quadratic effects on the crystallization behaviour causing wide variations in chocolate temper index during tempering of products with variable PSD and fat content. Differences in fat content exerted the greatest variability in temperature settings of the different zones for attaining well-tempered products. At 35% fat content, changes in PSD caused only slight and insignificant effect on tempering behaviour. No unique set of conditions was found to achieve good temper in dark chocolate with a specified tempering unit. Thus, different combinations of temperatures could be employed between the multi-stage heat exchangers to induce nucleation and growth of stable fat crystal polymorphs during tempering. Variations in tempering outcomes of the dark chocolates were dependent more on the fat content than PSD.

Industrial relevance

Tempering consists of shearing chocolate mass at controlled temperatures to promote cocoa butter crystallization in a stable polymorphic form. During industrial processing, multi-stage heat exchangers are used to control temperature adjustments to promote formation of appropriate stable polymorphic crystals to obtain products with good snap, colour, contraction, gloss and shelf life characteristics. The process employs varying time–temperature throughputs of the multi-stage units making it difficult to obtain standard tempering conditions for products with variable particle sizes and fat content, thus prolonging equipment standardization periods with consequential effects on processing times and product quality characteristics. Modelling the tempering behaviour of dark chocolates from varying PSD and fat content would enhance our knowledge and understanding on the optimal temperature conditions for obtaining good tempered products during industrial manufacture, with significance for reducing processing (tempering) times and assurances in quality and shelf characteristics.     

Effect of model heat treatment conditions on selected properties of milk fat

In this study, the effect of diverse thermal treatments on the physical characteristics of anhydrous milk fat was monitored with the use of scanning calorimetry, firmness analysis, electron microscopy and image analysis. The optimal properties of milk fat were achieved for the thermal treatment taking into account its composition as well as melting and solidification points of the main triacylglycerol fractions (temperatures: 6/20.5/14 °C). Unfavourable results were obtained for the one‐stage system (10 °C/13 h). These results may be helpful in optimising parameters of milk fat crystallisation in high‐fat products, and the fractal analysis has proven to be useful in the evaluation of fat crystallisation.     

The application of Borneo tallow in dark chocolate shell

Dark chocolate shells, formulated using cocoa butter (CB shell), and fat blends containing 15% Borneo tallow (IP) in cocoa butter (CBIP shell), were filled with truffles formulated using white chocolate (W truffle), milk chocolate (M truffle) and dark chocolate (D truffle). Anhydrous milk fat (AMF) content of the W truffles, M truffle and D truffle were 26·3%, 13·7% and 9·2%, respectively. Degree of tempering was determined using a tempermeter. The chocolates were kept at ambient temperature (25·5±0·5°C) for 3 months. Physical changes of chocolate shells and centres were monitored using DSC and a texture analyser. Results showed that the CBIP shell had to be tempered at 32·5%, ie 1°C higher than the normal CB shell. Physical measurements indicated the occurrence of fat migration. The presence of IP reduced the effect and increased the bloom resistance of the chocolate. © 1998 SCI.     

Effects of selected properties of ultrafiltered spray-dried milk powders on some properties of chocolate

The effects of selected properties of spray-dried milk fat powders on chocolate were determined. Milk powders produced from control or ultrafiltered (UF) milks with various levels of fat were blended with skim milk powder to give a standard 26 g fat 100 g⁻¹ powder. Particle size of the chocolate mixes after refining decreased as the fat content and free-fat content of the powders increased. Despite this, increasing fat and free-fat contents of powders reduced the Casson viscosity of the subsequent molten chocolates. Casson viscosities using powders from control or UF milks were similar, but decreased as the particle size of powders increased and particle size after refining the chocolate mix decreased. Casson yield value and hardness decreased as fat content of powders increased. Casson yield value increased with vacuole volume of powders. It is possible to alter important properties of chocolates using milk powders of varying fat contents, free-fat contents and particle sizes.     

Measurement of solid fat content by ultrasonic reflectance in model systems and chocolate

A series of confectionery coating fat (CCF) and cocoa butter (CB) dispersions in corn oil were prepared and tempered to a range of temperatures (10, 12 and 15 °C and 26, 27.5 and 29 °C respectively) to produce samples with solid fat contents (SFC) between 0 and 9%. The ultrasonic velocity in the CCF samples increased with increasing SFC and decreased with temperature, however the CB samples were too attenuating to allow velocity measurements. The ultrasonic reflectance at the surface of both sets of dispersions decreased linearly with SFC but at the same level of solids was less for CB than CCF suggesting some dependence on other aspects of fat structure. The microstructures and thermal properties of the fat systems are compared in an attempt to understand these structural differences. Finally ultrasonic reflectance is shown to respond to changes in a chocolate melt during tempering.     

Effect of dissolved carbon dioxide on the sonocrystallisation and physical properties of anhydrous milk fat

The effects of dissolved CO₂ (0–2000 ppm) coupled with ultrasound (US; 20 kHz) on the physical properties of anhydrous milk fat (AMF) were examined. Carbonated AMF was sonicated at 28 °C for 5 s at various amplitudes and subjected to isothermal (28 °C) and non-isothermal (cooling from 28 to 5 °C) crystallisation conditions. AMF microstructure, thermal properties and hardness were evaluated after 48 h of storage. In general, carbonated AMF samples treated with the same US amplitude exhibited a slight decrease in endset-melting temperature, smaller fat crystals with denser fat crystal network. Dissolved CO₂ caused harder texture of sonicated AMF at 25 °C. However, when carbonated + sonicated AMF samples was stored at 5 °C, their texture appeared to be softer than that of the control sample. A protective effect of CO₂ against formation of primary oxidative products during 90 days of storage was evidenced in both non-sonicated and sonicated AMF.     

The influence of formulation and cooling rate on the rheological properties of chocolate

Rheological properties of chocolate play a relevant role either in process design or texture definition. Nevertheless, only flow properties of molten product or mechanical properties of samples cooled at fixed temperature (usually 20 °C) are measured, whilst testing conditions close to the industrial applications (temperature close to 30 °C) are less common to be used. In this work, chocolate samples (cooled at 1 and 5 °C min⁻¹) were characterised at 30 °C by using small-amplitude oscillations and low-stress creep tests, aiming at establishing how material properties are related to the chocolate microstructure. The effects of either 3 anhydrous milk fats (AMF), having different melting points, or sugar particle size were evaluated. It was found that addition of AMFs, owing to their solid content, can yield an increase in consistency; however, this effect is less relevant when coarse sugar is used, because of the broader particle size distribution, and it depends on the thermal history because of the different fat crystallisation time. Finally, creep tests resulted to be very sensitive in detecting changes in chocolate rheological properties.     

Thermodynamic and whipping properties of milk fat in whipped cream: A study based on DSC and TD-NMR

The correlation between thermodynamic and whipping properties of milk fat when used in recombined dairy cream (RDC) was investigated; thermodynamic behaviour of milk fat and the microstructure of RDC were analysed. Differential scanning calorimetry curves of anhydrous milk fats (AMFs) showed two peaks (7 °C and 15 °C), implying a difference in the crystallisation mechanisms. RDCs whipped at 7 °C demonstrated significantly higher cream overrun, firmness, and shorter optimum whipping time in comparison with these attributes at 15 °C. Additionally, RDC whipped at 7 °C generated bigger milk fat globules and was characterised by less flocculation and fewer broken air bubbles. Comparative analysis of the whipping properties at 7 °C and 4 °C revealed no significant differences. The results suggest that 7 °C is a more suitable temperature than 15 °C at which to whip RDC, and an ideal alternative temperature to that of 4 °C, for lower energy consumption.     

Enzymatically modified tea seed oil as cocoa butter replacer in dark chocolate

Cocoa butter replacer (CBR) was prepared by enzymatic interesterification of hydrogenated and solid fraction (SF) of tea seed oil at weight percent ratio of 30:70, using sn‐1,3 specific lipase from Thermomyces lanuginosus. Dark chocolate samples were then prepared with the prepared CBR as a replacement for 5%, 10%, 15% and 20% of cocoa butter (CB) and the effect of the replacement on hardness (as a key quality factor in chocolate) of the chocolate samples was investigated. Results showed that chocolate samples containing 5% and 10% of interesterified sample (EIS), had the closer texture to that of CB chocolate than other samples. The solid fat content (SFC) profiles also revealed that blending 10% of EIS with CB in chocolate formulation dose not affect the sharp melting point of CB. Based on the results taken from bloom formation, polymorphic structure and sensory evaluation, adding up to 10% of EIS in chocolate formulation reduces the bloom development without adverse affecting the desirable β crystal formation and sensory qualities in the chocolate samples.     

Structural characteristics of cocoa particles and their effect on the viscosity of reduced fat chocolate

Aimed at the manufacture of reduced fat chocolates, a novel method of trapped fat reduction was assessed: Manipulation of the cocoa ingredient. Cocoa mass was replaced with cocoa powder (11 g/100 g or <1 g/100 g fat) and added ‘free’ cocoa butter. A cocoa solids approach to design reduced fat chocolates with satisfactory flow properties is attractive to industry since it circumvents introduction of ingredients not commonly used in chocolate manufacture. Results showed that the cocoa mass chocolate had a higher viscosity than cocoa powder chocolates of the same total fat content due to the presence of trapped fat globules as identified by confocal laser scanning microscopy. The chocolate prepared with standard defatted cocoa powder containing 11 g/100 g fat had a lower viscosity than the chocolate containing highly defatted cocoa powder (<1 g/100 g) due to particle shape and fat diffusion into the particles as revealed by microscopy analyses. Based on the evidence presented, it can be concluded that standard defatted cocoa powder, as widely used by the industry, is indeed the best compromise in terms of free fat, particle size and morphology attempting to formulate fat reduced chocolate of acceptable molten state viscosity.     

On the porous mesostructure of milk chocolate viewed with atomic force microscopy

The surface structure of commercial milk chocolate is examined using atomic force microscopy. It is shown that its surface topography is complex, comprising a finely mottled, yet irregular texture with most structural elements measuring <3 μm in size. It is also demonstrated that a large number of microscopic pores exists at the surface. The morphology of these pores is highly variable, with observed cavities generally being conical in nature with irregularly shaped openings. Typical pore depths range from 1 to 3 μm and are randomly distributed on the surface of milk chocolate, without any defining features in their vicinity to suggest their existence. In the past, it has been postulated that such pores are opening to channels; these being responsible for liquefied cocoa butter transport and subsequent promotion of fat bloom formation. To shed light on any such relationship, milk chocolate is subjected to multiple (6, 12 and 24) temperature cycles (each from 25 to 27 °C and 25 °C over 2 h). Results show that following many cycles, there is crystal growth around some pores, but that the pores themselves are not appreciably altered. This suggests that, under these experimental conditions, they are not directly involved in bloom mediation or liquefied fat transport in milk chocolate.     

Effect of surface-active stabilizers on the surface properties of coconut milk emulsions

Previously we have demonstrated improved stability of coconut milk emulsions homogenized with various surface-active stabilizers, i.e., 1 wt% sodium caseinate, whey protein isolate (WPI), sodium dodecyl sulfate (SDS), or polyoxyethylene sorbitan monolaurate (Tween 20) [Tangsuphoom, N., & Coupland, J. N. (2008). Effect of surface-active stabilizers on the microstructure and stability of coconut milk emulsions. Food Hydrocolloids, 22(7), 1233–1242]. This study examines the changes in bulk and microstructural properties of those emulsions following thermal treatments normally used to preserve coconut milk products (i.e., −20 °C, −10 °C, 5 °C, 70 °C, 90 °C, and 120 °C). Calorimetric methods were used to determine the destabilization of emulsions and the denaturation of coconut and surface-active proteins. Homogenized coconut milk prepared without additives was destabilized by freeze–thaw, (−20 °C and −10 °C) but not by chilling (5 °C). Samples homogenized with proteins were not affected by low temperature treatments while those prepared with surfactants were stable to chilling but partially or fully coalesced following freeze–thaw. Homogenized coconut milk prepared without additives coalesced and flocculated after being heated at 90 °C or 120 °C for 1 h in due to the denaturation and subsequent aggregation of coconut proteins. Samples emulsified with caseinate were not affected by heat treatments while those prepared with WPI showed extensive coalescence and phase separation after being treated at 90 °C or 120 °C. Samples prepared with SDS were stable to heating but those prepared with Tween 20 completely destabilized by heating at 120 °C.     

Thickening of molten white chocolates during storage

When white chocolates are kept molten in storage tanks, problems can arise due to uncontrolled thickening and solidifying of the chocolate mass. The thickening of molten white chocolate was simulated on a laboratory scale using a rotational rheometer under static conditions, interrupted by short shear periods to measure the increasing viscosity. Several chocolates having different dairy components and fat contents were investigated for their tendency to thicken. In addition, sorption isotherms for white chocolates were obtained using Dynamic Vapour Sorption at different temperatures. The sorption isotherms showed the presence of amorphous lactose in all the chocolates that were manufactured from milk powders. Moisture that is released during the crystallisation of amorphous lactose causes stickiness and agglomeration of the neighbouring particles and starts the thickening process. This process is highly temperature-dependent. On elevating the temperature the lactose crystallisation occurs at lower relative humidities. In order to reduce the tendency of white chocolate to thicken, a high free fat level should be maintained, based on a high total fat content and on the use of high free fat milk powders, preferably roller-dried whole milk powders or the combination of skimmed milk powder and anhydrous milk fat.     

The use of sedimentation field-flow fractionation in the size characterization of bovine milk fat globules as affected by heat treatment

Size distribution of fat globules affects the appearance, taste and stability of milk and milk-based products. Full-fat, semi-fat and chocolate bovine milk were subjected to heat treatment within a temperature range of 50–125 °C for 1 h. Sedimentation field-flow fractionation was employed to determine the changes in mean particle diameter of milk fat globules as affected by heat treatment. The mean particle diameter of fat droplets increased with increasing heating temperature for most samples. The particle size of fat globules increased on average 40 nm (4.65%) for full-fat and 72 nm (8.52%) for semi-fat milk following the heat treatment (50–125 °C). Chocolate milk exhibited considerable increase in particle size (104 nm, 12.53%) within a certain temperature range (50–110 °C), followed by a decrease in particle size when heated at 125 °C for 1 h. Heat-induced flocculation due to attractive interactions between hydrophobic sites on denatured protein molecules on different droplets was assumed to be mainly responsible for the increases in particle size observed in this study. Extensive heat-induced denaturation of milk proteins was also indicated by Native PAGE. Sedimentation field-flow fractionation proved to be a useful technique for adequately monitoring heat-induced changes in particle size distributions in milk.     

Microstructure and texture of white fresh cheese made with canola oil and whey protein concentrate in partial or total replacement of milk fat

A control white fresh cheese was prepared from milk containing 24 g milk fat (MF) L⁻¹, and nine white fresh cheese-like products were made by partial or complete substitution of milk fat by whey protein concentrate (WPC) and/or canola oil (CO) emulsified with an emulsifiers blend (EB) made of polyoxyethylene sorbitan monostearate (P), sorbitan monostearate (S) and glycerol monostearate (G) in 0.5:0.2:0.3 ratio. The textural characteristics and microstructure of the cheeses were assessed by Instrumental Texture Profile Analysis and Scanning Electron Microscopy. Polynomial models were obtained that estimated the composition and texture characteristics of the cheeses as function of the MF, EB (indirectly CO) and WPC concentrations in the cheese milk. CO incorporation promoted an open microstructure in the cheese, while WPC favoured a close and compact network made of short linking strands of milk proteins.MF, EB and WPC contributed positively to all the textural characteristics of the cheeses.     

Process development for continuous crystallization of fat under laminar shear

A novel continuous laminar shear structuring crystallizer with a suitable cooling system was designed and built. This is a new method to continuously crystallize edible fat in the desirable polymorphic form from the melt while being uniformly sheared.The machine consists of four main sections: Feed unit, shearing mechanism, cooling system and power unit. In each of these sections specific design considerations are taken into account which makes the process controllable and continuous. The shearing unit is made of two concentric cylinders. The internal cylinder is stationary and has a cooling system inside for temperature control. The outer cylinder rotates to produce a uniform shear in the sample fluid placed in the 1.5 mm gap between the cylinders. The sample’s feed rate is controlled while it is pumped to the gap. The cooling system has three segments and provides an individual temperature gradient for each region.Cocoa butter and a binary mixture of cocoa butter and milk fat were crystallized from the melt under shear and different cooling regimes. A major modification in the samples phase transition behavior was observed; laminar shear induces acceleration of phase transition from less stable polymorphic form to the more stable form, β_V. Moreover, X-ray diffraction patterns clearly showed crystalline orientation of the samples. This machine may open up new avenues for processing and manufacturing chocolate, shortenings and margarine.     

Pre-treatment methods of Edam cheese milk. Effect on cheese yield and quality

The effect of high-temperature heat treatment (HH), microfiltration (MF) and ultrafiltration (UF) on the Edam vat milk composition, processing and cheese yield, ripening and functional characteristics were studied. The protein level of the MF and UF cheese milk was adjusted to 42 g/kg, whereas the level in the reference (REF) and HH milk was 34 g/kg. The cheese yield from ultrafiltration and microfiltration milk (CY_v) was 12.8 g/100 g milk, yield from reference and high-temperature heat treatment milk was 10.1 and 10.2 g/100 g milk, respectively. The adjusted cheese yield (ACY_r), calculated from raw milk, was lowest when MF was used. The pre-concentration method had little effect on the starter activity: no differences were observed in the pH of cheeses. The compositions of the ripened cheeses were comparable. The casein to fat ratio of MF cheese was elevated, possibly due to elevated casein to fat ratio of vat milk. Even though the high-temperature heat treatment, ultrafiltration and microfiltration cheeses were harder than reference cheese, they retained their elasticity. Resilience was significantly higher with microfiltration and ultrafiltration cheeses. The sensory quality of all cheeses was considered according to specification. The pre-treatment methods had little effect on the processing characteristics, cheese quality or yield when calculated on the basis of the quantity of original milk.