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The potent odorants of regular-fat and low-fat Cheddar cheese were systematically characterized by aroma extract dilution analysis and gas chromatography/olfactometry of static headspace samples. Quantification of nine odorants using stable isotopes as the internal standards and calculation of odor activity values revealed methional, 2(5)-ethyl-5(2)-methyl-4-hydroxy-3(2H)-furanone (homofuraneol), diacetyl, acetic acid, and butyric acid as odorants with high aroma impact. Among the highly volatile compounds, the role of methanethiol and dimethyl sulfide for the nasal perception of the cheese flavor was established. The low-fat Cheddar cheese had a meaty-brothy odor defect that is believed to be caused by significantly higher amounts of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol), homofuraneol, and methional in this cheese. Keywords: Cheddar cheese; regular fat; low fat; AEDA; static headspace; odor activity value

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The volatile compounds in Parmigiano-Reggiano cheese were isolated by solvent extraction/high vacuum distillation, followed by separation into acidic, basic, water-soluble, and neutral fractions. The neutral fraction was further fractionated by a normal-phase liquid chromatography. Aroma compounds were identified using gas chromatography/Osme-mass spectrometry and confirmed with retention index of standards. Butanoic, hexanoic, octanoic, and decanoic acids are the major free fatty acids contributing to cheesy, lipolyzed aroma. Ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl propanoate, ethyl pentanoate, ethyl heptanoate, and ethyl decanoate are the major esters contributing to fruity aroma. 2-Methylbutanal, 3-methylbutanal, 2,4-hexadienal, 2-butenal, pentanal, hexanal, heptanal, diacetyl, phenylacetaldehyde, dimethyltrisulfide, and methional were identified to be odor-active. It was found that 2,3-dimethylpyrazine, 2,6-dimethyl-pyrazine, 2,5-dimethyl-3-ethylpyrazine, trimethyl-pyrazine, 5-ethyl-2-methylpyridine, 2,3-dimethyl-5-ethylpyrazine, 2,3,5-trimethyl-6-ethyl-pyrazine, furfural, and 2-furanmethanol contribute to the nutty, roasted aroma in this cheese.

Type of atomization (centrifugal wheel and spray nozzle) and processing temperatures (2 different sets of inlet and exit temperatures) of spray drying were investigated for their influence on the physical properties and oxidative stability of encapsulated orange oil in a modified starch matrix. The former determined particle size and surface oil, whereas the latter affected density (both absolute and bulk) and moisture content. Total oil retention did not depend on either parameter. Processing temperatures had an effect on shelf life as they influenced parameters that determine oxygen porosity of the matrix.

The process parameters typically reported in the literature for the encapsulation of aroma compounds via coacervation are reviewed and their effects on capsule formation discussed. We then report on our approach to produce coacervates [liquid (limonene or medium chain triglycerides) or solid core (menthol)] using gum acacia/gelatin as wall materials. Manufacturing parameters were optimized to allow the production of consistent batches of coacervate microcapsules. Capsules were crosslinked with glutaraldehyde and freeze-dried. Coacervates were characterized for their structure and shape, size distribution, flavour load and water uptake rate. In addition, a brief storage study compared the ability of coacervate capsules and spray-dried capsules (using modified starch as carrier material) to protect limonene from oxidation. No detectable increase in limonene oxide could be detected in capsules made by coacervation over 25 days in storage at 45°C, whereas a significant increase in limonene oxide was detected in spray-dried powder over the same period. Encapsulation by coacervation (as described in this paper) appears to be an effective technique for encapsulating aroma compounds and provides a good barrier against oxidation of sensitive material.

The objective of this study was to evaluate the potential of selected proteins as alternative materials for flavor encapsulation by spray drying. Two traditional materials (gum acacia and modified starch) and three proteins (sodium caseinate, whey and soy protein isolates) were used at different infeed solid levels; test compounds included (R)-(+)-limonene and three alpha,beta-unsaturated aldehydes ((E)-2-hexenal, (E)-cinnamaldehyde, citral). The primary criteria for performance were flavor retention during drying and protection against losses during storage. Limonene oxidation and nonenzymatic browning were investigated as two possible deterioration routes. Overall, higher infeed solids improved retention during drying and limited flavor losses (aldehydes and limonene) during storage in traditional materials only. The materials giving the highest flavor retention during drying were gum acacia (94%), modified starch (88%) and whey protein isolate (87%). Gum acacia provided the highest retention of aldehydes during storage (37 to 58%) after 28 days at 40 degrees C but did not afford good protection against limonene oxidation. Oppositely, protein materials effectively limited limonene oxidation (>70% retained). Nonenzymatic browning was observed for all powders prepared with proteins, especially whey protein isolate, whereas no browning occurred with traditional materials.

Glc of the pyrazine fraction from roasted cocoa beans yielded nine well resolved peaks which could be quantitated. When beans from several producing countries were roasted under identical conditions, pyrazines generated varied between 142 µg/ 100 g of beans and 698 µg/100 g. The potential for generating pyrazines was greatest in samples from countries where beans are traditionally fermented.