Identification of pork in beef meatballs using Fourier transform infrared spectrophotometry and real-time polymerase chain reaction

A study on development of Fourier-transform infrared spectrophotometric method combined with principle component analysis as well as real-time polymerase chain reaction for determination of pork–beef mixture in meatballs has been performed. A lipid component extracted from pork and beef in meatballs is analyzed using Fourier-transform infrared spectroscopy, while DNA extracted from meatball was analyzed using real-time polymerase chain reaction. The correlation between actual and predicted concentration of lard using Fourier-transform infrared spectroscopy was performed by aid of partial least squares, while grouping of lard and beef fat components in meatball was carried out by Fourier-transform infrared spectra coupled with principle component analysis. The results showed that Fourier-transform infrared spectra at wavenumbers of 1000–1200 cm^?1 coupled with partial least square and principle component analysis are successfully used for quantification and classification of pork in beef meatballs. The relationship between actual value and predicted value of lard (lipid fraction obtained from meatballs containing pork) with Fourier-transform infrared spectrophotometric method revealed good correlation, with coefficient determination (R²) value of 0.997 and standard error of calibration of 0.04%. Principle component analysis is able to classify samples containing pork and beef meatballs. Fourier-transform infrared spectroscopy using normal spectra is fast technique for identification and quantification of lard extracted from pork in meatball. In addition, real-time polymerase chain reaction using Leptin Primer–AJ 865080 can be used for amplification of pork DNA specifically in meatballs containing pork.     

彩色花生巧克力豆加工工艺技术及设备

本文介绍了制作花生巧克力所需设备以及设备的基本工作原理、构造和使用方法;探讨了彩色巧克力豆制作过程的工艺条件和配方。采用巧克力花生豆成套设备,以花生为芯料,可可粉、可可脂、糖粉、卵磷脂、色素和抛光剂按一定的比例,可制作出来色泽光亮、营养丰富、风味独特的花生巧克力豆。     

低场核磁共振在线检测巧克力的熔化过程

构建了低场核磁共振(LF-NMR)在线控温分析系统,对不同品种巧克力的熔化过程进行了表征,研究了可可脂和粗脂肪含量对巧克力熔化温度的影响。通过对样品的程序升温,持续测定了巧克力的横向弛豫时间(T₂),对四个不同品牌巧克力的熔化过程进行了评价。结果表明,巧克力熔化过程中T₂值随温度增大,巧克力中液体脂肪的运动性增强,且熔化温度随可可脂和粗脂肪含量的增加而升高。本文首次利用LF-NMR在线控温分析系统实时在线检测了巧克力熔化过程,并直观准确地测定了巧克力的熔化温度,为改善巧克力的加工工艺和配方提供了理论指导。     

巧克力专用乳粉

研究了不同乳粉的颗粒大小和结构、游离脂肪含量对巧克力浆料粘度的关系。滚筒乳粉与喷雾乳粉之对比，滚筒干燥的全乳粉具有下列优点；游离脂肪含量高，可减少可脂的用量，赋与巧克力以更好的风味；可降低巧克力浆料的粘度。乳粉中羟甲基糠醛含量可增进巧克力风味、口感，提高喷雾乳粉中游离脂肪含量改进的工艺。     

Use of Palm Mid-Fraction in White Chocolate Formulation

Samples of two types of palm mid-fraction (PMF I, a commercial sample and PMF II, from a laboratory-scale acetone fractionation of PMF I) and a Malaysian deodorised cocoa butter sample were used as the main components in the fat phase for white chocolate formulation. The monounsaturatedtriacylglycerol contents of these fats were 853, 899 and 903 g kg⁻¹, respectively.All the fats had free fatty acid contents of less than 10 g kg⁻¹ and melting points in the range of 34·0–34·5°C. The solid fat content profiles for the three fats were very steep. Differential scanning calorimeter analyses showed that all the fats had two melting peaks, T1 and T2. Results of the study showed that the tempering time to produce a well-tempered chocolate using PMF I was longer than that using PMF II, whereas, the time to produce a well-tempered cocoa butter chocolate increased with increase in the tempering temperature. Chocolates made with PMF I and II were well tempered between 17 and 19°C and with cocoa butter at 23°C. Thermal analyses, carried out on the chocolate showed that PMF I and II produced three melting peaks, T1, T2′ and T2 whereas most of the cocoa butter chocolates exhibited only one melting peak, T2. Storage studies showed that most of the chocolates had good bloom resistance for up to 12 weeks storage.     

纯脂巧克力用脂及其分析、应用研究进展

近年来纯脂巧克力日渐受欢迎,但可可原料面临产量有限且不稳定的制约因素,限制了纯脂巧克力的发展。作为与可可脂组分及特性最为接近的可可脂替代品,类可可脂的原料来源广泛,产品稳定性有提升空间,并且在提升纯脂巧克力品质方面有改善作用,因此类可可脂的相关研究也获得国内外广泛关注。通过对可可脂及类可可脂的组成、结晶特性、分析方法及纯脂巧克力的耐霜、抗热品质改善等方面进行综述,以期对纯脂巧克力用脂、巧克力品质改善等提供相关参考。     

Ochratoxin A in cocoa and chocolate sampled in Canada

In order to determine the levels of ochratoxin A (OTA) in cocoa and cocoa products available in Canada, a previously published analytical method, with minor modifications to the extraction and immunoaffinity clean-up and inclusion of an evaporation step, was initially used (Method I). To improve the low method recoveries (46-61%), 40% methanol was then included in the aqueous sodium bicarbonate extraction solvent (pH 7.8) (Method II). Clean-up was on an Ochratest? immunoaffinity column and OTA was determined by liquid chromatography (LC) with fluorescence detection. Recoveries of OTA from spiked cocoa powder (0.5 and 5 ng g(-1)) were 75-84%; while recoveries from chocolate were 93-94%. The optimized method was sensitive (limit of quantification (LOQ) = 0.07-0.08 ng g(-1)), accurate (recovery = 75-94%) and precise (coefficient of variation (CV) < 5%). It is applicable to cocoa and chocolate. Analysis of 32 samples of cocoa powder (16 alkalized and 16 natural) for OTA showed an incidence of 100%, with concentrations ranging from 0.25 to 7.8 ng g(-1); in six samples the OTA level exceeded 2 ng g(-1), the previously considered European Union limit for cocoa. The frequency of detection of OTA in 28 chocolate samples (21 dark or baking chocolate and seven milk chocolate) was also 100% with concentrations ranging from 0.05 to 1.4 ng g(-1); one sample had a level higher than the previously considered European Union limit for chocolate (1 ng g(-1)).     

Analysis of potential lard adulteration in chocolate and chocolate products using Fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy, in combination with attenuated total reflectance (ATR) and partial least square (PLS) regression, was used to detect the presence of lard in chocolate formulation. The spectral bands associated with lard, cocoa butter and their blends (ranging from 0% to 15% of lard in cocoa butter) were recorded, interpreted and identified. A semi-quantitative approach is proposed to measure the percent of lard in blends on the basis of spectral data at the frequency region 4000–650 cm⁻¹, using the equation y = 0.9225x + 0.5539. The coefficient of determination (R²) was 0.9872 with a standard error (SE) of 1.305. In this paper, the potential of FTIR spectroscopy as a rapid analytical tool for the quantitative determination of adulterants especially lard, in chocolate, is demonstrated.     

Cadmium and lead in cocoa powder and chocolate products in the US Market

Cocoa powder and chocolate products are known to sometimes contain cadmium (Cd) and lead (Pb) from environmental origins. A convenience sample of cocoa powder, dark chocolate, milk chocolate, and cocoa nib products was purchased at retail in the US and analysed using inductively coupled plasma mass spectrometry to assess Cd and Pb concentrations. Cd and Pb were evaluated in relation to the percent cocoa solids and to the reported origin of the cocoa powder and chocolate products. Cd ranged from 0.004 to 3.15 mg/kg and Pb ranged from <LOD to 0.38 mg/kg. Cd and Pb were significantly correlated with percent cocoa, with correlations varying by product type and geographic origin. Geographic variation was observed for Cd, with higher Cd concentrations found in products reported as originating from Latin America than from Africa. The influence of percent cocoa solids and cocoa origin on Cd levels are relevant to international standards for Cd in chocolate products.     

Solid Fat Content,Pre-Crystallization Conditions,and Sensory Quality of Chocolate with Addition of Cocoa Butter Analogues

The objective of this study was to determine how the addition of two cocoa butter equivalents and cocoa butter improver affect the physical and sensory properties of chocolate. The laboratory-made chocolate samples were tempered at three different pre-crystallization temperatures (25, 27, and 29°C), using different concentrations (3, 5, and 7%) of two commercial cocoa butter equivalents as well as commercial cocoa butter improver of the chocolate. The nucleation time of the chocolate mass primarly depended on pre-crystallization temperature while the value of maximum torque of chocolate mass were influenced by both, pre-crystallization temperature and concentration of fats. Sensory evaluation revealed that cocoa butter equivalents were acceptable in chocolate formulation without producing a negative impact on the sensory quality, while usage of improver required adjustment of raw formulations or process parameters. The results of the instrumentally measured hardness revealed that addition of cocoa butter improver significantly (p > 0.05) increased hardness of chocolate samples.     

Fat Bloom and Chocolate Structure Studied by Mercury Porosimetry

The structure of dark chocolate samples was analyzed by mercury porosimetry in order to determine whether the formation of fat bloom was related to the presence of pores. The influence of cocoa butter concentration and tempering conditions on porosity were determined by using samples containing 29.5 or 31.9% fat, which were under, well or over-tempered. All Mercury porosimetry analysis confirmed the presence of a porous structure in all chocolates. Empty spaces represented about 1% of the whole volume of a well-tempered chocolate containing 31.9% cocoa butter but made up about 4% of the over-tempered chocolate. A well-tempered chocolate with only 29.5% cocoa butter showed the presence of about 2% empty spaces. From these observations and gas permeability a possible model for the microscopic structure was developed.     

Chocolate Swelling during Storage Caused by Fat or Moisture Migration

Abstract: Quantification of swelling in dark chocolate subjected to fat or moisture migration was conducted using a new method based on confocal chromatic displacement sensor. The nondestructive method allowed for the height profile of dark chocolate samples to be scanned with a sensitivity of ± 2.8 μm. By performing multiple scans on each sample prior to and after being subjected to fat or moisture migration, the induced swelling could be quantified. Applying the new method on confectionery systems revealed that fat and moisture migration generate different swelling behavior/kinetics in dark chocolate during storage. Moisture migration resulted in a rapid swelling once a water activity of 0.8 was reached in the chocolate, probably by interaction and absorption of moisture by the particulate solids. Fat migration also affected the swelling behavior in chocolate, possibly by inducing phase transitions in the continuous cocoa butter phase. Migrating fat also proved to induce a more pronounced swelling than the same amount of absorbed moisture which further consolidated that the observed swelling caused by fat or moisture migration is a result of significant different mechanisms.     

Comparison of classical and alternative extraction methods for the quantitative extraction of fat from plain chocolate and the subsequent application to the detection of added foreign fats to plain chocolate formulations

Three methods were compared for the quantitative extraction of fat from plain chocolate and cocoa products ranging from simple intermediary products such as cocoa butter, cocoa masses or liquors to market purchased chocolate samples. The classical method of extraction using an acid digestion followed by Soxhlet extraction was compared to two potentially alternative methods: microwave extraction and supercritical fluid extraction (SFE). The extracted intact triacylglycerols were then analysed directly by high temperature capillary gas chromatography (HT-GC). The results of extractions were compared by plotting the percentage areas of the three major triacylglycerols present one vs. the other. The results showed that the microwave extraction technique gave similar results to the more time-consuming classical extraction method. SFE gave results with higher standard deviations and a tendency to lower yields taking the acid digestion–Soxhlet method as the reference method. The minimal variations due to the methods did not impact the detection of foreign fats added to chocolate. However, the quantification of the foreign fats was impaired when using the SFE method compared to the other techniques due to the larger variations of replicate analyses of intact triacylglycerol profiles.     

Development of a Chocolate Flavored Peanut Beverage

Nine chocolate-flavored peanut beverages (CFPB) were prepared using peanut protein isolate as source of protein and analyzed for physical-microbiological-sensory qualities. The quality attributes such as color, aroma, viscosity, and flavor of CFPB were similar to that of commercial chocolate milk. The total aerobic populations of the beverage before and after refrigeration for 7 days were less than 10 and 200 colonies/g, respectively, and no coliform bacteria was detected in this product. Sensory evaluation and response surface methodology indicated that optimum formulation of CFPB was obtained by using 3.5% protein (from peanut protein isolate), 3.5% butter, 8% sugar, 0.7% cocoa powder, 0.1% stabilizer, and water. Consumer study of the CFPB revealed that all sensory characteristics were acceptable in the range of like to extremely like.     

The Precursors of Chocolate Aroma: Production of Reducing Sugars during Fermentation of Cocoa Beans

SUMMARY— The sucrose in fresh cocoa beans is hydrolyzed to glucose and fructose during fermentation and the rate of the reaction confirms the possible inclusion of reducing sugars among the precursors of chocolate aroma. The optimal concentration of reducing sugars in the bean is reached at about the same time as maximal flavor development, and coincides approximately with the peak in amino acid concentration. An objective method for assessing the "Degree of Fermentation" of cocoa beans has been proposed and tested.     

巧克力样品中反式脂肪酸含量的测定

采用气相色谱内标法,对20个巧克力样品中的反式脂肪酸含量进行测定分析。试验结果表明,以代可可脂为主要原料的巧克力样品中,反式脂肪酸含量范围在未检出至4．96％之间。以可可脂为主要原料的巧克力样品中,反式脂肪酸含量范围在未检出至0．844％之间。所测定的巧克力样品中反式脂肪酸以反十八碳一烯酸为主。     

Tempering of Chocolate in a Scraped Surface Heat Exchanger

Crystallization of dark chocolate during different tempering processes has been studied in-situ in a lab-scale Scraped Surface Heat Exchanger. The linear relationship between torque and viscosity made possible the control of chocolate crystallization during tempering by following torque variations vs. time and converting them to equivalent viscosity values. These variations of equivalent viscosity of chocolate observed during tempering were correlated with temper-meter measurements which had been related to the content of cocoa butter seeding crystals. A temperature cycle (50-26.1-30.5-33.3°C) enabled preparation of a well-tempered chocolate stable for ≥30 min at that temperature. It was characterized by a seed crystals content of about 1.15 ± 0.1% of cocoa butter, crystallization temperature of 23.9 ± 0.2°C in the temper-meter and an equivalent viscosity of 3.0 ± 0.4 Pa.s.     

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.     

香菇、茶叶抗类可可脂巧克力脂霜之形态学研究

用偏光显微镜和扫描电镜在形态学方面就香菇和茶叶抗类可可脂巧克力脂霜进行了研究 ,电镜结果表明 ,香菇和茶叶巧克力的质构呈链状有规则排列 ,而对照样则呈杂乱零星无规则排列。偏光显微结果说明 ,无论是起霜还是未起霜的香菇和茶叶巧克力 ,其晶相均呈有规律的均匀分布 ,而对照样则无规则性可言。在相同的促霜时间内 ,对照样起霜程度比香菇和茶叶巧克力大