Heat resistant chocolate development for subtropical and tropical climates: a review

Figures & data

Figure 1. Major chocolate consuming and cocoa producing countries around the globe (ICCO, 2017).

Figure 2. Statistical distribution of cocoa production around the globe and the share of the world’s top cocoa bean producing countries (Data source: ICCO 2017).

Figure 3. Temperature regimes and degree of stability of six polymorphic forms of cocoa butter (Adapted from: Beckett 2008).

Figure 4. Different methods for production of heat resistant chocolate and associated features.

Figure 5. Ternary diagram showing the melting points for mixtures of the main cocoa butter TAG. (Adapted from Garti and Widlak 2012).

Figure 6. Effect of chemical (or random) interesterification of a mixed TAG on a TAG composition (Adapted from Garti and Widlak 2012).

Table 1. Use of interesterified fats as coco butter equivalents (CBE).

Author & year	Method employed	Interesterification mechanism	Heat resistance behavior
Bruse, Wallecan, and Arruda 2008	Chemical /enzymatically interesterified CB (direct*) added (10% w/w). *Direct interesterification at a lower temperature (25–35 °C) allows less soluble triglycerols of CB to crystallize, specifically the SSS triglycerols (Gunstone 2004).	Chemical – using 0.4% sodium methoxide (reaction for 30 min at 95 °C) Enzymatic – 2% lipase (reaction at 70 °C for 6 h).	Chemical – slip melting point went up to 33 °C only. Enzymatic – slip melting point ranging up to 42.5 °C, chocolate had better sensory characteristics.
Soekopitojo et al. 2009	Interesterified palm oil mid fraction blends (6% w/w) added	Solvent free enzymatic interesterification using Lipozyme TM IL Lipase	Slip malting point ranging between 45.2 °C and 50 °C.
Bahari & Akoh, 2018	Interesterified Illipe butter added to white chocolate (32% w/w).	Enzymatic interesterification of Illipe butter using immobilized Lipozyme® RM IM Lipase	Melting range of chocolate stretched up-to 39.4 °C with higher breaking strength.
Jin, Akoh, et al. 2018	Palm oil interesterified blends Interesterified Blend- 20% hard palm mid-fraction (HPMF)+ 60% mango kernel fat-third stearin (MKF-TS) + 20%CB Physical blend- 10% HPMF+ 55% MKF-TS +35% CB	Lipozyme RM IM Lipase used for both interesterified blend and physical blend (10%)	Higher solid fat content- 55.7–60.9g/100g. Melting temperatures raging up-to 40.7 °C (interesterified blend) and 39.2 °C (physical blend).
Yamoneka et al. 2018	Hydrogenation employed to interesterified blend of Irvingia gabonensis seed fat and Dacryodes edulis pulp oil (90:10)	Interesterification done via Lipozyme TL IM Lipase, 4%	Hydrogenation can improve the melting characteristics
Zhang, Song, et al. 2020	Palm oil based interesterified fats (palm oil: fully hydrogenated palm oil: palm kernel oil- 4:3:3 as base oil)	Interesterification using Lipozyme TL IM Lipase	Two small endothermic peaks showing melting temperature range of 22–50 °C with some samples having lower offset melting temperature of 45.1 °C. Sample CBS-37 with palm kernel oil and interesterified fat in 30:70 w/w ratio showed more hardness and firmness.

Table 2. Development in “Fat structure modification” method to produce HRC after 2011.

Author (s) & Year	Method/Principle	Heat Resistance Behavior
Jeyarani and Reddy 1999	Incorporated mahua (Madhuca latifolia) and kokum (Garcinia indica) stearin fractions (solvent fractionation) to CB.	Rapid crystallization was observed with steeper melting point and higher solid fat content at 32.5 °C. But around 37.5 °C, the solid fat content reached < 20% indicating a product flaw at high tmperatures.
Maheshwari and Reddy 2005	Refined kokum fat used without fractionation (5% w/w)	Melting point up-to 34.8 °C was achieved with increased hardness and solid fat content but with poor sensory quality attributes (above 32.5 °C).
Tran et al. 2015	Incorporation of hard StOSt rich fats (31.6% w/w) from Vietnamese mango fat and Indian mango fat and its stearin and olein fractions.	Heat resistance to 38 °C was achieved by maintaining 70:30 ratio of Cocoa Butter: Vietnamese Mango Fat. Dark chocolate composed of Vietnamese fat and stearin fraction of Indian mango fat provided heat resistance till 36–38 °C with increased bloom resistance and less oil release.
Andersen 2016 (Patent No: WO 2016/ 200323 A1)	Modified fats* (60–99.9% w/w; from various natural sources) were added with crystalline seeding material (0.1-15% w/w), CBI (5–40% w/w) and emulsion other than lecithin. *Fat was modified by regulating the saturated: oleic acid via transesterification (by enzymes having 1, 3 specific activity or an acid, or a base or a non- enzymatic catalyst or a combination thereof).	Heat resistance up-to 46–48 °C was achieved by addition of AOA (A = Arachidic acid) triglycerols and up-to 50–53 °C by BOB (B = Behenic acid) triglycerol addition. Most of the formulations were able to retain their shape till 38 °C.
Wang et al. 2016	Incorporation of a combination of hard StOSt rich palm mid-fat fractions with mango fat fractions	Heat resistance till 37-38 °C was observed for some combinations.
Oonishi and Hachiya 2016	Adding a seeding material (0.1–15% of fat/oil present) containing at least a β-form XOX triacylglycerol crystal (BOB or StOSt; B: Behenic), with water (0.1–55 of chocolate mass) at high temperature (32–40 °C)	The end product had a good mouthfeel and did not collapse after 20 min (up-to 24 h) after dipping it in hexane at 20 °C (up-to 50 °C) attributed to the formation of saccharide skeleton in chocolate.
Rosales, Klinkesorn, and Suwonsichon 2017a, 2017b	Use of hydrogenated palm olein (30% w/w) with crystal promoters (0.25–0.5% w/w ;mono, di and tri glycerides and esters from sunflower oil, canola oil and palm stearin)	Heat resistance till 40 °C was achieved with delayed bloom formation as well as glossy texture and less waxiness and improved mastication properties.
Jin, Akoh, et al. 2018, Jin et al. 2019	Adding 55–60% mango kernel fat (MKF) third stearin in physical blend as well as stereo-specifically interesterified blend.	MKF improved the shape retention properties of the samples at 40 °C. These chocolates showed hardness for 8 h at 37 °C with melting peaks as high as 37.3–38.6 °C with better fat bloom resistance.

Table 3. Development of organogelation technique for HRC.

Author (s) & Year	Method/principle	Heat resistance behavior
Marangoni 2010 (Patent: WO 2010/143067 A1; Mars Inc.)	Creation of secondary gel network by fat substitution method. Ethyl cellulose: sorbitan monostearate: palm kernel oil (18:6:76 w/w) was heated and added to chocolate samples (1:3–1:9 w/w) to bind liquid oil. Final EC content – 0.5–5% (w/w).	Heat resistance up-to 52 °C was observed with firm texture and minimal oil migration.
Stortz and Marangoni 2013	Use of ethyl cellulose by solvent substitution method to create a gel for binding the liquid oil.EC was added via dissolving it in EtOH to give 80/20 toluene/EtOH solution.	Heat resistance up-to 40 °C was observed
Peyronel and Marangoni 2014	Addition of hydrogenated palm kernel oil stearin (HPKOS) + sorbitol monostearate (SMS) to produce a heat resistant secondary network	Heat resistance up-to 40 °C with at least 40% of SMS. Melting point increased with more addition of SMS.
Patel et al. 2014	Use of shellac oleogels in chocolate paste formations. Shellac (2% w/w) replaced the oil binder on 1:1 ratio in the paste. Palm oil was also replaced by 27% liquid rapeseed oil which, in presence of shellac wax, formed an oleogel.	The product was just checked to study the oil binding characteristics of shellac oleogels without proper emphasis on HRC.
Fayaz, Goli, and Kadivar 2017	Use of pomegranate oil-based oleogel with structuring agent (5%; beeswax, propolis wax and monoglyceride) and palm oil in 1:1 (w/w) in functional chocolate spread.	The gel binding characteristics of the product were checked and it was observed that chocolates made with these oleogels (esp. monoglycerides) showed much firmer and harder texture at higher temperatures.
Francis and Chidambaram 2019	Sodium alginate and pectin were used to prepare a hybrid hydrogel combining both physical and chemical cross-linking methods with citric acid being the cross- linker.	High melting resistance going as high as 80 °C (50% v/v hydrogel dispersed chocolate) observed with a porous network structure (SEM micrographs).
Wendt and Flöter 2017	Added 10% or 25% sterol structured organogels (2.5% or 14% w/w) based on γ-oryzanol and β- sitosterol 1:1 mixture in pralines to prevent oil migration.	Chocolate paste, with 2.5% oleogel (25% structurants) had reduced oil migration by 50% when kept for 6 months.

Table 4. Development of direct water incorporation technique in HRC.

Author (s) & Year	Method/ principle	Heat resistance behavior
Russell and Zenlea 1948 (U.S. Patent No. 2,457,110)	Addition of 17–23% warm water (48.8-65.5 °C) to molten refined chocolate paste without conching.	No flow behavior observed till temperatures between 37.8 and 48.9 °C.
Lataner 1949 (U.S. Patent No. 2,487,931)	Addition of 4–20% water to conventional chocolate composition and then heating to a temperature greater than 65.5 °C.	Able to withstand any climatic temperature
Noznick, Tatter, and Obenauf 1963 (U.S. Patent No. 3,098,746)	Mixed 4 parts chocolate in 6 parts water at 63 °C in the presence of sugar to create an oil-in-water emulsion. The resulting powder was then dispersed into melted chocolate in a 6:10 ratio of powder to chocolate and mixed for 3–5 h at 29–31 °C.	A similar product did not soften at temperatures greater than 46 °C, with some formulas withstanding up-to 120 °C.
Jeffery, Glynn and Khan (U.S. Patent No. 4,045,583), 1978 (U.S. Patent No. 4,081,559)	Created w/o emulsion along with sugar and thereafter evaporated water with the final water content of about 5% after processing. Sugar network left after water evaporation was thought to entrap fat.	No flow behavior up-to 65.5 °C
Jeffery 1979 (U.S. Patent No. 1,538,750)	HRC was produced as oil in water emulsion with permitted gum or gelling agent such as gelatin (1–2%)	Not reported as such
Giddey and Dove 1991 (European Patent No. 0,407,347)	Incorporated water as foam prepared by adding 0.1–30% surfactant to water and whipping in the presence of suitable gas. For viscosity enhancement, polyols or carbohydrates were added. The final chocolate had 0.1–5% of water in the form of foam.	The resultant product remained solid up-to 50 °C.
Takemori et al. 1993 (U.S Patent No. 5,232,734)	HRC was produced by forming o/ w emulsion with a droplet size of 0.1–20 µm. This emulsion was then added at levels of 1–10% to tempered conventional chocolate	The product was able to maintain its shape at 50° after 10 days of aging.
Oonishi, Toyoma, and Murayama 2017	Sugar skeleton was created with powdered sucrose (30–58 mass %), crystalline lactose (1–20 mass %) and water (0.3–3 mass %). A holding time (1–240 h) was provided (24–36 °C) to improve the strength of the sugar skeleton.	The resultant chocolate retained its shape for <72 h when it was dipped in n-hexane at 20 °C and showed a resistance to stress under load measurement.

Table 5. Development of Polyol Addition Technique in heat resistant chocolate (HRC).

Author (s) & Year	Method	Heat Resistance Behavior
Finkel 1987 (U.S. Patent No. 4,664,927) 1989 (U.S. Patent No. 4,812,318) 1990 (U.S. Patent No. 4,980,192)	HRC was made by adding liquid polyol in 0.2–5% amount.	The resultant chocolate (with 1% glycerin) showed no fluidity till 48.9 °C.
Kincs 1992 (U.S. Patent No. 5,108,769)	HRC was produced by firstly emulsifying the polyols in fat with a solid content of 50–75% to delay their action. About 2–10% of this polyol was then added with an emulsifier. The final product had 2% polyol.	The product did not deform at 38 °C after some storage time.
Mandralis and Weitzenecker 2001 (European Patent No. 0,668,506)	HRC was produced by dispersing 0.2–60% polyol throughout the chocolate via diffusion out of gel particles formed by common gelling agents (gelatin, pectin) by conventional gelling techniques.	The process created HRC that was hard at 40 °C but heat resistance required 3–29 days to develop depending on the formula.
Mandralis and Weitzenecker 2001 (European Patent No. 0,668,506) Best et al. 2005 (U.S. Patent Application No. US 2005/0118327 A1)	A method to produce gel particulates was employed by dispersing gelling agent in cold polyol and adding it to molten CB. This mixture was heated above dissolution temperature of gelling agent (90–170 °C) with stirring to form an emulsion.	The process created HRC that was hard at 40 °C but heat resistance required 3–29 days to develop depending on the formula. Further, gels containing water and polyol hardened in much less time than gels with no water.
Wentzel et al. 2014 (International Publication No. WO 2014/052421 A1)	Addition of glycerol (via premix) along with a thermal structuring component (dextrose monohydrate).	The samples began deformation at 38 °C after 20 min. It was concluded that the addition of monosaccharide in the premix formed a heat resistant structure with polyol before the addition of bulk sweetener that later contributed to the texture and strength.
Potter 2014 (U.S. Patent No. US20160000113A1)	A heat resistant coating with one layer having 3% (w/w) or less glycerol and/ or at least one layer consisting solely of glycerol.	The resultant product showed full melt resistance to heat when heated at 35 °C for 1h even after 4 weeks.

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