Character impact odorants of high-heat skim milk powder isolated by simultaneous distillation-extraction.
To identify the character impact odorant of high-heat skim milk powder (HHSMP), a comparative study using ultrahigh-temperature (UHT) milk was performed. Aroma concentrate was prepared by column adsorption combined with simultaneous distillation-extraction. Aroma extract dilution analysis (AEDA) revealed 58 aroma peaks with flavor dilution (FD) factors ranging from 10 to 3000; from these, 41 compounds were identified and 7 compounds were tentatively identified (FD factor > or = 300). Among these HHSMP and UHT milk components, methyl 2-methyl-3-furyl disulfide and bis(2-methyl-3-furyl) disulfide, which appeared to be generated during the processing of each product, were identified. When the results of the AEDA of both samples were compared, it was considered that the characteristic aroma of HHSMP was not explained by a single compound but instead formed from a mixture of several types of compounds contained in common with the UHT milk. The contribution of these compounds to the aroma of HHSMP was confirmed by an aroma simulation experiment.
Quantitation of Nine Lactones in Dairy Cream by Stable Isotope Dilution Assays Based on Novel Syntheses of Carbon-13-Labeled γ-Lactones and Deuterium-Labeled δ-Lactones in Combination with Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry.
Lactones are well-known aroma compounds in, e.g., fruits and fermented foods as well as in dairy products, such as cream or milk powders. The latter are often used in confectionary products, e.g., milk chocolate. Lactones are suggested to contribute to the distinct aroma of dairy products and have also been reported in milk chocolate. However, data on their contribution to the overall aroma of this type of chocolate are scarce. As a result of their pH-dependent instability and their low volatility, a reliable quantitation of lactones is a challenge. Thus, to allow for a quantitation of nine lactones in one single comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry in electron ionization mode run, new synthetic routes were developed for five carbon-13-labeled γ-lactones and four deuterium-labeled δ-lactones, with the isotope label in the ring to be used in stable isotope dilution assays. The concentrations of the nine lactones were then analyzed in raw and pasteurized cream as well as in a heat-treated raw cream. δ-Dodecalactone and δ-decalactone showed the highest concentrations in both the raw and pasteurized cream. In the latter, δ-dodecalactone reached a 2.5-fold higher concentration compared to the raw cream. Subsequent heat treatments in a lab scale showed a further increase by factors of 13 and 19, respectively, suggesting a high potential of lactone precursors in cream. The results serve as a basis for further studies on lactone formation in other thermally processed products, such as milk chocolate.
Influence of Flavor Variability in Skim Milk Powder on Consumer Acceptability of Ingredient Applications
Flavor variability in skim milk powder (SMP) has been documented by descriptive sensory analysis and instrumental analysis. However, research has not addressed how or if SMP flavor variability impacts consumer acceptance of ingredient applications. Twenty reconstituted low-heat SMPs were screened using a previously established defined sensory language. Two SMPs free of off-flavors (flavor similar to fresh fluid skim milk) and 2 SMPs exhibiting off-flavors (exhibiting flavors not found in fluid skim milk) were selected for further study. Volatile compounds were determined using solid phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS). Each SMP was subsequently directly reconstituted or incorporated into standard formulas for vanilla ice cream, strawberry yogurt, hot cocoa mix, and white chocolate bars. Consumer acceptance testing was conducted. Descriptive panelists documented sweet aromatic and cooked flavors in the fresh-flavored SMP and these flavors as well as fatty/fryer oil and animal-like flavors in the off-flavored SMP. Concurrently, instrumental volatile analysis revealed higher relative abundances of lipid oxidation compounds in the off-flavored SMP. Consumer acceptance scores were lower for the off-flavored SMP than for the fresh-flavored SMP when evaluated directly reconstituted (P < 0.05) and for ingredient applications made using off-flavored SMP (P < 0.05). Off-flavors in SMP documented by descriptive analysis and trained panelists can carry through into ingredient applications with SMP and negatively affect consumer acceptability.