Garlic techniques

Thiocarbonyl oxides are a subject of active investigation. The natural occurrence of sulfines and related compounds in plants of the genus Allium (onion, garlic, etc.) is included in a superb and extensive review by Block [91]. Two detailed papers [92, 93] report the isolation of zwiebelanes from onions and their chemical synthesis involving intermediate sulfines produced by oxidation of di-l-propenyl disulfide, subsequent sulfoxide accelerated [3.3] sigmatropic shift and the [2+2] cycloaddition of the C=S and C=S=0 moieties. A further article [94] provides a great deal of information on the mechanism of formation of (Z)-propanethial S-oxide, the lachrymatory factor of the onion, as well as its chemical synthesis and reactions. Techniques of analysis of the volatiles of onions have been further improved [95]. 

You can use essentially the same technique for other vegetables as well. Asparagus stalks are particularly delicious roasted in that fashion, as is broccoli. You can add some minced garlic cloves to the asparagus. Also try beets. To roast potatoes, cut them in chunks with the skins still on and boil them for a few minutes to soften them a bit before putting them in the oven. 

The analysis of natural compounds in foods is also assisted by the use of the purge and trap technique in methods for distinguishing strawberry varieties [100] the aroma of unprocessed foods including gherkin [101], durian [102], garlic [103] and meat [104-107] cheese [108,109] and other dairy products [110] tobacco, tea and coffee [111,112] and peanuts [112]. Food additives including sulphur dioxide [113,114] and food contaminants such as VOCs [115-126], have been recovered by PT, particularly from table-ready foods. Animal [127,128] and plant tissues [129,130] have also been subjected to PT for separation of volatile compounds. 

The harshest technique is steam distillation, which involves boiling garlic followed by extracting compounds from condensed steam. Steam-distilled garlic oils consist of the diallyl (57%), allyl methyl (37%) and dimethyl (6%) mono- to hexasulfides. These oils are diluted (>99%) with vegetable oils to obtain a practical-sized pill and to stabilize the sulfides (Lawson, 1993). 

Recently, a variety of sulfijr- and selenium-bearing compounds were identified through the use of GC/MS techniques [51-53], element specific technique of gas chromatography with atomic emission detection (GC-AED) [54], and by proton-transfer-reaction mass spectrometry (PTR-MS)[55] in the breath of persons after the ingestion of garlic. 

The method used to process garlic can also influence the nature and levels of the sulfur compounds that predominate some of the compounds found in various garlic preparations are shown in Table 2. The new analytical technique described by Arnault et al. [27] may assist in characterizing the impact of various processing methods on the content of the individual allyl sulfur compounds. 

But the cane symboUzed the physician even before this rather inventive technique became widespread. In the seventeenth century, doctors carried canes with hollow gold heads full of garlic-laced Marseilles vinegar, which was rumored to have kept four plunderers of dead bodies from contracting the plague. To ward off infection, the doctors would repeatedly sniff the vinegar. 

Although tomato was the matrix most studied with this technique, other matrices such as pepper, eggplant, apple, pear, beans, mango, orange, citrus fruit, onion, garlic, potato, chillies, and strawberries were also studied by UAE. The extracted phenolic compounds included phenolic acids, isoflavones, flavonols, flavonones, fla-vones, flavonones, cinnamic acids, dihydrochalcones, chalcones, flavanols, and pro-cyanidins (Table 16.3). 

Lee, S.N., Kim, N.S., and Lee, D.S. 2003. Comparative study of extraction techniques for determination of garlic flavor components by gas chromatography-mass specirometry. Anal Bioanal Chem 577(4) 749 756. 

Sharma and Prasad (2006b) optimized the process parameters for the microwave-convective drying of garlic cloves using a constrained optimization technique (Tukey s multicomparison pair-wise test), in an effort to identify the best compromise between quality and drying time. The results revealed that a... 

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