调温和油脂组成对巧克力原料油及其应用性能的影响

Effects of Tempering and Fatty Acid Composition on the Compatibility and Applicability of Chocolate Fats

研究调温和油脂组成对巧克力油脂（可可脂与全氢化棕榈仁油硬脂混合物）的相容性、巧克力的质构以及在20℃贮藏3个月过程中起霜稳定性的影响。结果表明：可可脂与全氢化棕榈仁油硬脂混合物未调温时随可可脂含量增加有明显的稀释作用,经调温后可可脂含量在30%~50%之间出现明显共晶;巧克力硬度受调温和巧克力油脂相容性影响显著。当巧克力油基中可可脂含量〈50%,巧克力硬度随可可脂增加而降低;当可可脂含量〉50%,经调温巧克力硬度显著增加而未经调温巧克力硬度较为恒定。20℃贮藏实验发现：未调温,巧克力可可脂含量越高,起霜越显著;调温后,样品可可脂含量在10%~50%范围内起霜程度降低,当可可脂含量〉50%及纯全氢化棕榈仁油硬脂时,产品得到明显改善而无起霜现象。从巧克力的熔化特性和巧克力表层的脂肪酸组成分析发现,当可可脂含量〉50%时,未调温巧克力引起起霜的机制是不稳定晶体向稳定晶体转化;当可可脂含量≤50%时,引起起霜的机制是可可脂与全氢化棕榈仁油硬脂较差的相容性,导致部分油脂迁移至表面重结晶。

The effects of tempering and fatty acid composition on the compatibility of chocolate fats, i.e., cocoa butter（CB） blended with fully hydrogenated palm kernel stearin（FHPKS）, the hardness of chocolate and chocolate blooming during storage at 20 ℃ for 12 weeks were evaluated. Without tempering, the isosolid phase diagram showed a dilution effect with increasing proportion of CB. With tempering, an eutectic behavior occurred when the mixtures contained 30% 50% CB. Tempering and compatibility of chocolate fats had a signif icant effect on the hardness of chocolate. The hardness was decreased with increasing CB from 0 to 50%. When the content of CB was higher than 50%, two different trends occurred, i.e., the hardness of the tempered chocolate increased obviously whereas the hardness of the non-tempered one kept constant. During storage of chocolate at 20 ℃ for three months, it was found that tempering was an important factor affecting chocolate blooming. All the non-tempered chocolate had bloom within 3-month storage tests, and the degree of bloomingfor non-tempered chocolate was positively correlated to the CB content. After tempering, 10% 50% CB had less bloom formation than the non-temper ones whereas the products containing 60% 100% CB kept glossy. The results of DSC and fatty acid compositions indicated that polymorphic transformation from the unstable to the stable state was the reason for the bloom of non-tempered chocolate containing ＆gt; 50% CB, and the mechanism for bloom formation of chocolate with ≤50% CB may mainly be attributed to the lipid migration due to the incompatibility between CB and FHPKS.