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Dr Sakai Odourless Garlic

Introduction

Chewing leafy plant material such as parsley after a garlic meal has long been recognised as a way of freshening the breath and reducing the malodour associated with garlic. This effect can be associated with other plant material and in particular the use of green tea leaves is well documented as is the Indian custom of chewing pan after a meal. Other methods of deodorising garlic include bonding garlic to peptides and/or saccharides , treatment with fumaric acid , the use of high pressures , soaking in saline and microwave irradiation . Numerous other techniques have been put forward over the years and some products have been launched commercially, primarily in the health-food or nutraceutical sectors.

The Fundamentals of Breath Malodour in The Journal of Contemporary Dental Practice gives a good introduction to the subject. A copy of the paper can be downloaded here (pdf).

One product that has been the subject of further study is a product known as 'Dr. Sakai Odour-Free Garlic.' This is a product that has been patented world-wide and is (or was) on sale commercially in Japan and the USA, where it has FDA approval. According to the Sakai process, the whole garlic bulbs are simply soaked in a solution containing 'natural silica and organic plant material' and then dried. The resultant product has the appearance of an ordinary garlic bulb and, as the deodorising process is claimed to act upon a biological pathway unrelated to the production of the primary garlic flavour, the flavour of Dr Sakai garlic is also said to be unaffected. The development of the malodour associated with 'garlic breath' is however claimed to be arrested.

See USA Patent Office abstract
Read full UK Patent No. 2217570 (pdf)

Background to Sakai garlic

Dr. lsao Sakai is an agricultural scientist and President of the Sanko Chemical Institute in Tokyo, Japan. He holds a number of patents on odour control and first applied for a UK patent for Sakai garlic in 1988. There was some press coverage in The Grocer in 1987 and in 1990 but nothing since appears to have been reported. 'Dr. Sakai' garlic is available in retail packs in Japan and is (or was) manufactured in the USA by a New Jersey-based company who have advertised the product on the internet.

Flavour Chemistry

Clearly there is little point in developing a method of deodorising garlic if the initial flavour itself is adversely affected. Whilst Dr. Sakai's claim is that the flavour is unaffected by the process this is clearly a main precondition upon which the possible use of Sakai garlic would be based. It is well understood that the primary flavour compounds in garlic are the thiosulphinates which are formed when garlic tissue is crushed. In a study of thiosulphinates by Block et al., Dr. Sakai garlic was assessed and the HPLC result is shown in Figure 1 alongside that of an untreated garlic sample.



  Figure 1. HPLC analyses of Dr. Sakai & untreated garlic samples (Block et al. 1992)

Taste panels have been conducted to assess the flavour of the fresh and cooked 'Sakai' cloves and each has shown the Sakai garlic equal in flavour to untreated garlic. These findings bear out the results of Block et al shown in Figure 1.

The Development of Garlic Breath

A number of sulphur-containing volatiles are responsible for the formation of garlic breath. Laasko et al were among the first to make the distinction that the composition of sulphur- containing volatiles was different when garlic-borne volatiles are generated in the mouth versus the garlic odour compounds present in garlic breath. By the use of headspace technique they identified two major sulphur compounds in exhaled air - allyl mercaptan (2-propene-1-thiol) and diallyl disulphide. Minami et al later confirmed allyl mercaptan as the major garlic-borne compound while diallyl disulphide is secondary.
In a later study by Ruiz et al, the breath concentrations of various allylic sulphur-containing garlic-borne phytochemicals were measured and their results are summarised in Figure 2. Levels of methyl allyl sulphide, allyl thiol, diallyl sulphide and diallyl disulphide were all originally high but found to drop precipitously within a relatively short period of time (1-3 hours). The slope of the curves changes dramatically by leveling off and remaining constant throughout the rest of the sampling interval. It is believed that the initial high levels and rapid decline of the sulphur compounds are related to their elimination from the oral and pharyngeal regions where they are present as residues immediately after the ingestion of garlic. The leveling off region is claimed to represent bloodstream elimination of the compounds via gas exchange in the lungs. The trials conducted by Ruiz et aI confirmed that the time taken for the change coincided with the time expected for digestion and bloodstream absorption.



Figure 2. Breath concentrations of various compounds after ingestion of fresh garlic (Ruiz et al.)

While the residual levels of sulphides and allyl mercaptan appear low, sensitivity to these compounds is high with detection levels in ppm and even ppb.

Dr Sakai Garlic - mode of action.

The processes described in Sakai's patent involve soaking the garlic bulbs in a deodorising solution containing mesoinositol hexaphosphate and silicic acid. The bulbs become impregnated with the solution and are then dried before use.
In the patent Sakai attributes the malodour of garlic to the combination of sulphides and mercaptans generated by the garlic within the bulb and presumably also after crushing and ingestion. He goes on to state that alliin (S-allyl-L-cysteine sulphoxide), the precursor to the formation of allicin when garlic tissue is ruptured, undergoes an enzymatic decomposition within intact garlic tissue to form a compound called aricine (16,17-didehydro-10-methoxy-19a-methyloxayohimban-16-carboxylic acid) and that it is as a result of this decomposition of alliin to aricine that mercaptans are formed.
The patent claims that the mesoinositol hexaphosphate has the effect of coagulating the enzyme that is responsible for the alliin to aricine reaction thereby significantly reducing the levels of mercaptan. It further claims that the process involves increasing the temperature of the deodorising solution (in which the bulbs are soaked) and that this causes a vigorous enzymatic formation of mercaptans within the garlic tissue. Subsequent lowering of the temperature and the introduction of pressure differentials cause the deodorising solution to be taken up and to act upon the cell contents. The silicic acid 'mops up' the free sulphides (including mercaptans) while the mesoinositol hexaphosphate acts upon the enzyme that causes mercaptans to be generated. The final stage of the process involves again reversing osmotic pressures so that the 'spent' deodorising solution is removed. The bulbs are then dried and processed in the normal way.

Verification

Sakai states that the malodour associated with garlic is due to a combination of sulphides and mercaptan. This is supported by the research paper published by Minami et al (1989) who confirmed that the major compounds in exhaled air were primarily allyl mercaptan with diallyl disulphide as a secondary contributor.
The mechanisms described by Sakai are more challenging and these specific pathways are at present beyond the scope of this study.
R. Yamamoto of Ricom Corporation of Japan has independently tested Sakai garlic and whilst the results are not statistically valid, they do give an indication of the effectiveness of the Sakai product. Note that the results were obtained from subjects who held garlic in their mouths and did not ingest so the compounds measured will be principally from garlic tissue retained in the mouth and on the teeth and not from gas exchange via the lungs.



 
Time Elapsed
(min)
Methyl mercaptan
(ppm)
Dimethylsulphide
(ppm)
Allylmethylsulphide
(ppm)
Untreated
0
0.0208
0.0214
0.0000
 
5
0.3000
0.0211
0.5440
 
35
0.0786
0.0229
0.0289
 
Dr Sakai
0
0.0000
0.018
0.0000
 
5
0.3139
0.0169
0.0702
 
35
0.0000
0.0000
0.0219

Table 1. GC Breath Analysis (Ricom Corp.)

Dr Sakai has published his own results for measured mercaptans and these are reproduced here from the UK patent. Note that the different examples refer to varying mix proportions of the deodorising solution.

 
Time Elapsed
(min)
Methyl mercaptan
(ppm)
Ethyl mercaptan
(ppm)
Propyl mercaptan
(ppm)
Untreated
10
6.3
7.2
2.5
120
5.8
6.1
1.4
Example 1
10
1.9
2.2
1.5
120
1.7
1.8
0.8
Example 2
10
3.7
4.3
1.7
120
3.5
3.7
0.9
Example 3
10
1.0
1.2
1.1
120
0.6
1.0
0.5
Example 4
10
1.5
1.8
1.2
120
1.2
1.4
0.5

Table 2. Breath Analysis by GC (Sakai 1988)

Since there is no correlation between subjects and amounts of garlic eaten, only a general trend can be considered. Methyl mercaptan is the only common compound to have been measured but the results clearly indicate that its production must be a function of conversion within the body. The results in Table 1 which measure garlic held in the mouth show only negligible amounts of methyl mercaptan whilst Sakai's results in Table 2 show nearly twenty times as much only 10 minutes after ingestion. Methyl mercaptan levels derived from the ingestion of untreated garlic show little change after 120 minutes whilst all of the treated samples show significantly lower levels of methyl mercaptan both at the start and end of the test.

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