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Garlic - Processing, properties and toxicity


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1       Introduction Garlic  (Allium  sativum  L.)  is  the  second  most  widely  cultivated  Allium  after  onion. According to FAO estimates for the year 1999, the world area cultivated is 889,000 ha and production is 8,776,000 mt. China, Korea, India, USA, Spain, Argentina and Egypt are  the  major  garlic  growing  countries.  China  ranks  first  in  area  (424,000  ha)  and production  (5,690,000  mt)  followed  by  India  in  area  (113,000  ha)  and  Korea  in production (484,000 mt) (Table 1). In productivity, Egypt tops the list (25,366 kg/ha) followed by USA (16,250 kg/ha), China (13,421 kg/ha) and Korea Republic (11,916 kg/ ha). Korea Republic has the highest per capita availability, i.e. 10.50 kg per year followed by  Argentina  (5.01  kg)  and  China  (4.53  kg).  The  world  garlic  area,  production  and productivity trends during the past decade show that since 1986 they have improved by about  115.78%,  245.92%  and  60.41%,  respectively  (Table  2).  Garlic  is  in  demand almost  all  the year round all over the world both in fresh form and also in dehydrated form. Today, garlic is used for its flavour, aroma and taste being prepared domestically or forming a raw material for a variety of food manufacturing processes (dehydration and pickling).

Fresh  garlic  is  widely  used  in  cooking.  In  India  and  other  Asian  and  Middle  East countries, it is used in pickles, curry powder, curried vegetables, meat preparation, tomato ketchup. In the Philippines, Central Eastern Asia and in parts of the tropics, the green tops as well as bulbs of garlic are used. Dehydrated garlic in powdered or granulated form has replaced the use of fresh bulbs for industrial and home use in many countries. Dehydrated products of garlic are common as a condiment and in the food industry. It is reported that in  America  about  50% of the  total  production of garlic  is dehydrated and  sent to food processors.

Garlic  is  a  frost-hardy  bulbous  perennial  erect  herb  of  30–100  cm  in  height  with narrow  flat  leaves  and  bears  small  white  flowers  and  bulbils  (Janick,  1979).  It  is  a herbaceous  annual  for  bulb  and  a  biennial  for  seed  production.  The  shape  of  garlic  is smooth, round and solid for its entire length unlike onion which is hollow. Many cloves of  garlic  do  not  produce  flowerstalks.  The  inflorescence  may  be  partially  or  not  at  all

Table  1    Area,  production,  productivity  and  per  capita  availability  of  garlic  in  different countries during 1999

Country           Area                 Production       Productivity     Per capita

(’000 ha)         (’000 mt)         (kg/ha)             availability


Africa                  17                     178             10311

Algeria                   8                      30               3750                 1.00

Egypt                      5                     114             25366                1.73

Morocco                2                        7               3829                 0.26

N.C. America      25                     301             12218

Mexico                   9                      65               7647                 0.68

USA                     14                     224             16250                0.82

South America

Argentina             15                     181             11727                5.01

Brazil                   11                      63               5563                 0.38

Peru                       5                      30               5883                 1.21

Asia                    682                  7280             10667

China                  424                  5690             13421                4.53

India                   113                    452              3996                 0.46

Indonesia             11                      38               3599                 0.18

Korea Rep.           41                     484             11916               10.50

Turkey                  14                     106              7571                 1.64

Myanmar              14                      53               3782                 1.19

Bangladesh           13                      40               3022                 0.32

Thailand               21                     131              6235                 2.17

Europe               125                    699              5594

Italy                        4                      34               8550                 0.59

France                    6                      45               7759                 0.77

Yugoslavia           12                      44               3631                 4.14

Russian Fed.        25                     161              6381                 1.09

Romania               12                      58               4833                 2.58

Spain                    25                     170              6827                 4.29

Ukraine                21                      79               3762                 1.55

Oceania                 –                        1               7143

New Zealand         –                        1               7143                 0.26

World                 889                  8776              9875                 1.49

Source: FAO Quarterly Bulletin of Statistics (3/4) 1999.

exerted, its bulbils forming a swelling somewhere within the false stem a few cm above the bulbs. The bulb consists of 6–35 smaller bulblets called cloves and is surrounded by a thin white or pinkish papery sheath (Bose and Som, 1986).

Alliums   have   been   cultivated   for   thousands   of   years   for   therapeutic   and prophylactic  properties,  religious  significance,  and  flavour  and  taste.  The  Chinese,

Table 2    Trend of area, production and productivity of garlic in the world


1986                1999                Increase (%)

Area (million ha)                         0.41                 0.89                 115.78

Production (million ton)              2.54                 8.78                 245.92

Productivity (ton/ha)                   6.16                 9.88                   60.41

Sources: FAO Quarterly Bulletin of Statistics (3/4) 1999 and FAO Production Year Book 1988.

Sumerians, Indians and Ancient Egyptians are all known to have consumed garlic over

4000  years  ago.  Among  others,  Hippocrates  (430  BC)  and  Theophras  Tuso  (322  BC)

have   described   the   consumption   of   garlic   in   the   Greek   and   Roman   period

(Rabinowitch  and  Brewster,  1990).  Garlic  is  thought  to  have  originally  come  from Central  Asia  and  Southern  Europe,  especially  the  Mediterranean  region  (Thompson and  Kelly, 1957). Some  authorities consider  that  Allium  longicuspis  Regel,  which  is endemic  to  Central  Asia,  is  the  wild  ancestor  and  spread  in  ancient  times  to  the Mediterranean region.

Garlic  presents  an  interesting  problem  of  classification  and  quality  given  the  wide range of cultivars, differing in maturity, bulb size, clove size and number, scale colour, bolting,  number  and  size  of  inflorescence  bulbils  and  presence  or  absence  of  flowers

(Bose  and  Som,  1986).  Taxonomists  have  recognised  at  least  four  botanical  varieties within  Allium  sativum  L.,  namely  A.  sativum  L.,  Var  sativum,  A.sativum  L.  Var., Ophioscorodon  (Link)  Doll,  A.  sativum  L.  Var  Pekinense  (Prokh)  Maekawa  and  A. sativum  L.  Var  nipponicum  Kitamura.  Jones  and  Mann  (1963)  could  not  satisfactorily classify many garlic cultivars into clearly defined botanical varieties, because many show combinations of characteristics from two or more varietal groups. It appears, then, that the  above  botanical  classification  has  little  advantage.  Following  criteria  may  be  of practical  use  for  distinguishing  different  garlic  cultivars  (Rabinowitch  and  Brewster,


   Morphological  characteristics  such  as:  Bolting  type,  number  and  size  of  cloves, number of leaf axils, forming cloves, number of secondary cloves formed in a lateral bud,  bulb  weight,  colour  of  the  outer  protective  leaf  of  the  cloves,  number  of protective leaves, width and length of foliage, plant height and tenderness of the green leaves.

   Physiological  and  ecological  characteristics:  Time  of  bulbing  and  maturity,  low temperature and long day requirements for bulb formation, winter hardiness and bulb dormancy.

2       Chemical structure

Garlic  or  any  other  Allium  is  characterised  by  the  remarkable  sulphur-containing compound present in it which gives distinctive smell and pungency. Uninjured bulb of garlic contains a colourless, odourless water soluble amino acid ‘Allii which includes the presence of the volatile flavour compounds. These precursors are of the general name S-alk(en)yl cysteine sulphoxide. The general structure of the flavour precursor is:




The group to the right of R moiety is the –L-cysteine sulphoxide group. The group R can be:

1.   CH3—                     -called (+)-S-methyl

2.   CH3—CH2—CH2—       -called (+)-S-propyl

3.   CH3—CH=CH—    -called trans (+)-S-(1-propenyl)

4.   CH2=CH—CH—    -called (+)-S-(2-propenyl)

When the fresh tissue is damaged, the flavour precursors react under the control of the enzyme alliinase (S-alk(en)yl-L-cysteine sulphoxide Lyase) to release the highly reactive sulphenic acids plus ammonia and pyruvate. Alliin, or S-allyl cysteine sulphoxide, was the first sulphur compound isolated from Allium sativum (garlic). The enzyme alliinase is confined  to  the  cell  vacuole,  whereas  the  flavour  precursors  are  confined  to  the cycloplasm  probably  within  small  vesicles  associated  with  their  presence  in  the  cell. Hence the enzyme has access to the precursors only when cells are disrupted. In garlic, alliinase catalyses the formation of allicin, which gives fresh garlic its characteristic smell

(Brewster, 1994).

Alliinase   (E.C.,   S-alk(en)yl-L-cysteine   sulphoxide   cyase   is   the   enzyme ultimately  responsible  for  the  development  of  the  flavour  compounds.  The  reaction catalysed by the enzyme is a beta elimination of the S-alk(en)yl sulphoxide group from the substrate:




|                                                               ||            NH2        NH

Both   products   of   the   reaction   are   chemically   unstable;   the   Ketimore   product spontaneously  hydrolyses  to  pyruvate  and  ammonia  while  the  reactive  sulphur  species will  combine  with  any  of  a  number  of  co-reactants,  most  often  another  of  the  same species, to give a range of flavour components. Thus the reaction is commonly described as:

O                                                     O             O       

||                                              ||                        ||


| NH2

Rabinowitch  and  Brewster  (1990)  have  elaborated  the  details  about  the  alliinase solubility  and  stability,  purification,  physical,  chemical  and  catalytic  properties.  They report that alliinase from Alliums is less soluble. It is difficult to maintain this enzyme in aqueous solution. A cosolvent  is required to maintain the enzyme  activity. It is further reported that alliinase enzyme has a tendency to aggregate and precipitate and gets totally inactivated by freezing.

Alliinase from garlic was first prepared by Stoll and Seebeck in 1947; however, the preparation  was  relatively  crude.  A  common  feature  of  the  preparation  is  the  use  of  a polyalcohol  cosolvent,  10%  glycerol  in  the  case  of  garlic  enzyme.  The  purification  of garlic  enzyme  also  required the  presence  of 10  M pyridoxal  phosphate  in  the  buffers. The garlic enzyme has been described as having a molecular weight of 130,000 with two subunits of 65,000. Spectral studies on alliinase from garlic revealed an absorption peak at  420 nm  characteristic  of  pyridoxal  phosphate.  Garlic  alliinase  has  been  reported  to contain no carbohydrate. However, the presence of a subunit band giving a periodic acid– schiff  base  stain  on  SDS  gels  of  the  purified  enzyme  indicates  that  the  enzyme  is  a glycoprotein.

The  general  catalytic  properties  of  alliinase  were  well  described  long  before  the enzyme was purified to homogeneity. A broad pH optimum of 8 was described by Stoll and  Seebeck  (1947)  for  the  garlic  enzyme  with  a  temperature  optimum  under  the

condition  of  assay  of  37C.  They  also  made  observations  on  the  specification  of  the reaction:  the  substrate  must  be  a  derivative  of  (-)L-cysteine,  the  sulphur  atom  must  be linked to an aliphatic group, the amino group of cysteine must not be substituted and the sulphur atom must be in the sulphoxide form with the + and                                                                                     configurations both being substrate.

3       Processing Raw  garlic  no  doubt  has  the  ideal  flavour  and  provides  desirable  textural  and  water retaining properties when incorporated into food products, bulk of raw garlic is water and lacks flavour and aroma. Also handling and storage costs are more when garlic is used in raw form. Dehydration or flavour extraction reduces the quantity which ultimately lowers the  transportation  and  storage  costs.  Processing,  however,  may  introduce  undesirable changes in appearance. It may also modify the natural balanced aroma and flavour.

Many modern automated food processing plants are not able to handle the raw form of garlic as such a range of garlic products are available to meet the particular needs of the market. Garlic flakes, garlic powder, garlic oil and garlic juice are some of the processed forms of garlic which are widely used by the food industry. Garlic capsules and tablets are also prepared and these products have a ready market in view of their high medicinal values.

3.1       Garlic dehydration A schematic representation of the process for garlic dehydration is shown in Fig. 1. The garlic bulb is broken into individual cloves by passing between rubber covered rolls which  exert  throughpressure  to  crack  the  bulb  without  crushing  the  cloves.  The  loose paper shell is removed by screening and aspirating. The cloves are then washed in a flood washer. At this stage the root stubs are floated off. Slicing is then done on a specially designed high-speed cutter. The sliced garlic cloves are then spread on drying trays which in turn are stacked on transfer cans. Tunnel type dehydrators are used for dehydration. The  cans  are  placed  in  these  tunnels  and  hot  air  is  blown  across  the  trays.  The  sliced garlic cloves are dried down to about 10% moisture in this operation which takes about

10–15 hours at 60–65sC. It is, however, preferable to keep the temperature below 57sC

while drying (Pandey, 1997).

Part of the remaining moisture is usually removed in a finishing operation for which garlic cloves are placed in large bins. Warm air is forced upward through the bins. This bin  drying  and  conditioning  operation  may  take  about  30  hours.  In  these  drying operations temperature must be controlled so that browning or scorching do not occur. After the slices are dried, they may be screened for removal of large partially dried slabs and fines. The fines may account for one third of the total dehydrated product. Usually fines are  ground into  powder. The slabs may  be broken up and redried.  The  slices  are prepared  in  the  form  of  flakes.  Grinding  and  packaging  of  powder  is  done  in  low humidity  surroundings  to  avoid  gumming  and  caking.  Garlic  is  commercially  dried  to

6.5% moisture.

It  is  reported  that  dehydrated  garlic  is  available  in  six  forms:  powdered,  minced, coarse, granulated,  chopped and  diced.  It is generally  considered  that  about  5 kg fresh garlic  bulbs  from  the  field  make  1  kg  of  dried  product.  On  the  basis  of  chemical, microbial and sensory studies, it is also reported that 60sC is the maximum temperature

Fig. 1    A schematic representation of the process for garlic dehydration. (From Van Arsdel et al., 1973).

for  dehydration  of  garlic.  Hot  air  drying  technique  is  considered  to  be  the  most economical.  Storage  of  garlic  powder  was  best  achieved  in  cans,  the  use  of  sealed polyethylene  bags  being  considered  unsatisfactory.  Odourless  garlic  powders  as  health supplements may be produced by inactivating alliinase by contacting garlic with fumaric acid/fumarate or by physically separating garlic powder and alliinase. Freeze drying of the  garlic/cyclodextrin  (70:30)  mixture  has  also  been  claimed  to  produce  an  odourless product. Dehydrated garlic is prone to discoloration. Darkening is associated with non-

enzymic  Maillard  reactions  and  may  be  prevented  by  reducing  temperature.  A  green discoloration                     associated  with  the  maceration  of  garlic  tissue  may  be  minimised  if dormant tissue is processed (Rabinowitch and Brewster, 1990).

There are reports that there is adverse effect of processing on quality and intensity of flavour.  Dehydration  has  been  associated  with  loss  of  more  than  90%  of  the  flavour intensity  (Pruthi,  1980).  This  represents  both  a  potential  environmental  problem  and  a significant economic loss. The origins of such losses has been examined and it has been concluded  that   they  occur   prior  to  the  realisation  of  a  critical   moisture  content, wherefrom the flavour may be envisaged as being sealed within the product (Mazza and Le Maguer, 1979).

3.2       Garlic oils Volatile oils comprise 0.1 to 0.25% of the fresh weight of garlic. Garlic oil is recovered by steam distillation of freshly ground cloves. It is a reddish brown overpowering liquid. One  gram  of  oil  is  equivalent  in  flavouring  terms  to  900  g  fresh  garlic  or  200  g dehydrated  garlic  powder.  The  high  pungency  of  garlic  oil  makes  it  difficult  to  use directly. The oil is commonly diluted in vegetable oil. It is being used in ice-cream, ices, confectionery, baked goods, chewing gum and condiments. The rates of 6 ppm in baked products, 0.01–0.3 ppm in beverages, 16 ppm in condiments, 12 ppm in chewing gums,

12.9 ppm in confectionery and 40 ppm in ice-cream are being used.

3.3       Other products Garlic is also processed in the form of garlic juice and garlic salt. Garlic oleoresin is a dark viscous liquid, having 12 times the flavour of dehydrated garlic or 50 times that of fresh garlic cloves. Garlic paste is formulated from suitable flavours and viscous edible base.

Garlic  salt  is  comprised  of  a  free  flowing,  uniformly  blended  dry  mixture  of  non- iodised salt, the approximate composition of which is shown in Table 3. Garlic salt should  not  contain  more  than  2.5%  moisture,  more  than  81%  salt  and  should  have moisture-free white garlic powder between 18–19%, and 1–2% calcium stearate. Garlic

Table 3    Approximate composition (100 g) of garlic salt

Garlic salt Water       1.4 g Energy    63 kcal Protein                                                 3.2 g

Fat                                                       0.1 g Carbohydrate    13.8 g Fibre     0.4 g Ash                                                     81.5 g Ca       220 mg Fe        1 mg Mg                                                            11 mg

P                                                                             79 mg   

K                                                         212 mg Na     31.4 g Zn         1 mg Vitamins                                              –

salt has much wider culinary potential than powder and one tablespoon is equivalent to a clove of fresh garlic.

4       Uses Garlic  is  used  practically  all  over  the  world  for  flavouring  various  dishes.  In  America about 50% of the entire output of fresh garlic is dehydrated and sold to food processors for  use  in  mayonnaise  products,  salad  dressings,  tomato  products  and  in  several  meat preparations.  Raw  garlic  is  used  in  preparation  of  garlic  powder,  garlic  salt,  garlic vinegar,  garlic  cheese  croutons,  potato  chips,  garlic  bread,  garlicked  meat  tit-bits  and garlicked  bacon,  etc.,  which  have  been  boosted  in  the  American  market.  Spray-dried garlic  products  including  garlic  preparations  are  also  available  in  the  market.  In  Italy, Europe and Latin America, the spectacular popularity of garlic is shown by the methods by which it is boosted by the garlic growers. In India and other Asian and Middle East countries,  garlic  is  already  being  used  in  several  food  preparations  notably  in  pickles, curry powders, curried vegetables, meat preparations and tomato ketchup, etc. There has been  increasing  demand  for  garlic  by  the  food  industries  for  garlic  powder  as  a condiment. Oil of garlic has now been appreciated as a valuable flavouring agent, for use in all kinds of meat preparations, soups, canned foods and sauces (Pruthi, 1987).

5       Functional properties and toxicity Garlic  has  been  considered  as  a  rich  source  of  carbohydrate,  proteins and  phosphorus. Ascorbic acid content was reported to be very high in green garlic (Prodan et al., 1977). The nutritive composition of fresh and peeled garlic cloves and dehydrated garlic powder as reported by Pruthi (1987) is given in Table 4.

Studies suggest that  garlic,  which contains more than 200 different compounds, has biological activities that can have medically important effects. Garlic has been used as an excellent  carminative,  a  nerve  tonic  and  an  antiseptic  agent  in  Hindu  medicine  for centuries (Aman, 1969). However, it has been only recently that its medical benefits have been  explored  in  detail.  The  functional  properties  of  garlic  have  been  reviewed  by Agarwal (1996), Koch and Lawson (1996) and Lawson (1998a). These properties include the following:

   cholesterol  lowering  properties  reported  by  numerous  studies  (including  Reuter  and Sendl, 1994; Han et al., 1995; Adler and Holub, 1997). These studies have reported an average 10% reduction in total serum cholesterol. Evidence suggests that these effects are  due  to  allicin  or  allicin-derived  compounds  (Yeh  and  Yeh,  1994;  Gebhardt  and Beck,  1996).  Some  recent  studies,  however,  have  produced  contradictory  results

(Berthold and Sudhop, 1998), though this may be due to the composition of the garlic supplements studied (Lawson, 1998b)

   garlic significantly lowers blood pressure (Silagy and Neil, 1994; Das et al., 1995a and


   garlic has an influence on platelet aggregation, an important factor in cardiovascular disease  (Lawson  et  al.,  1992;  Han  et  al.,  1995;  Batirel  et  al.,  1996).  It  also  has  an effect   on   blood   coagulation   and   fibrinolytic   activity   which   are   factors   in   the development of thrombosis (Han et al., 1995; Breithaupt-Grogler et al., 1997)

Table 4    Nutritive composition of fresh/peeled garlic cloves and garlic powder (Pruthi, 1987)

Nutrients                                     Fresh peeled                    Garlic powder garlic cloves

1. Moisture (%)                           62.8                                 5.2

2. Protein (%)                               6.3                                17.5

3. Fat (%)                                     0.1                                  0.6

4. Mineral matter (%)                   1.0                                  3.2

5. Fibre (%)                                  0.8                                  1.9

6. Carbohydrates (%)                  29.0                               71.4

7. Calcium (%)                             0.03                                0.1

8. Phosphorus (%)                        0.31                                0.42

9. Iron (%)                                   0.001                              0.004

10. Sodium (%)                              –                                     0.01

11. Potassium (%)                          –                                     1.1

12. Niacin (%)                               –                                     0.7

13. Vitamin-A                                0                                   17510/100 g

14. Vitamin-B (mg/100 g)              0                                     0.68

15. Vitamin-B2  (mg/100 g)             0                                     0.08

 Vitamin-C (mg/100)                     13.00                               12.00

17. Nicotinic acid (mg/100 g)        0.4

18. Caloric value (food energy)  142 calories/100 g           380 calories/100 g

   epidemiological  studies  have  suggested  a  link  between  garlic  consumption  and  a reduced  risk  of  stomach  cancer  (Steinmetz  et  al.,  1994;  Han  et  al.,  1995;  Milner,

1996). Various constituents of garlic have been identified as inhibiting tumour growth, notably  garlic-derived  organosulphides  (Srivastava  et  al.,  1997;  Pinto  et  al.,  1997; Riggs et al., 1997; Hu and Singh, 1997; Sakamoto et al., 1997).

   Garlic  also  has  antioxidant  properties  which  are  helpful  in  preventing  cancer  and cardiovascular disease (Horie et al., 1992; Phelps and Harris, 1993; Imai et al., 1994).

   garlic  has  antibiotic  properties  and  has  been  used  to  treat  wounds  when  other antibiotics were not available (Fenwick and Hanley, 1985a; Han et al., 1995). Although  anticarcinogenic  activity  of  garlic  has  been  well  documented  (Lau  et  al.,

1990),  the  mechanism  by  which  garlic  compounds  prevent  carcinogenisis  of  many chemicals  is  not  entirely  clear.  One  possible  mechanism  is  the  ability  of  sulphur- containing garlic compounds to block the activation of procarcinogens to carcinogens by hepatic  mixed  function oxidases. It is interesting to note  that  diallyl  sulphide has been found  to  inhibit  hepatic  mixed  function  oxidases  at  high  doses  (Dalvi  and  Salunkhe,

1993). Garlic is also effective against gastric cancer.

5.1       Toxicity of garlic

Since  the  consumption  and  level  of  sulphur-containing  ingredients  of  garlic  that  are supposed to be toxic are so low, acute or fatal garlic poisoning in humans is very rare. A case report on wild garlic poisoning in sheep indicates that the poisoned animals showed hemolytic anemia, jaundice, very dark discoloration of the kidneys and hemoglobinuria

(Stevens,  1984).  Histopathological  examination  of  the  dead  animals  showed  a  marked tubular  necrosis  and  hemoglobin  casts in  the  kidneys  and  centrilobular  necrosis  of  the liver. These toxic effects were attributed to a high level of S-methylcystein sulphoxide, a sulphur-containing amino acid which is a precursor of hemolytic anemia factor dimethyl

disulphide  found  in  garlic.  Compounds  such  as  di(prop-2-enyl)  disulphide  present  in garlic  have  been  found  to  cause  contact  dermatitis  (Mitchell,  1980;  Hjorth  and  Roed- Peterson, 1976) and may also be responsible for occupational allergy.

The mechanism of toxic action of sulphur-containing compounds of garlic, especially allicin, has been reported to lie in their ability to react with –SH groups of enzymes and properties. Therefore, though garlic has many medicinal  properties, it has serious toxic effects,  if  taken  in  large  quantities  for  medicinal  uses,  which  may  present  as  anemia, stomach ulcers, severe allergic reaction and suppression of testicular functions. Further studies on safety of garlic are thus needed.

6       Quality issues

The  quality  of  the  raw  material  used  in  the  processing  industry  determines  to  a  large extent  the  quality  of  the  finished  product.  Raw  materials  of  poor  quality  cannot  be expected  to  result  in  a  final  product  of  high  quality  even  with  the  best  processing methods. Therefore, gaining an understanding of the nature of the raw material and of its possible defects is an essential step in building quality into a product. Likewise thorough knowledge  of  the  likely  effects  of  defects,  defective  raw  materials  on  both  processing efficiency and quality  of finished product is important. The bulb of garlic  should have been harvested at proper maturity  stage and tacked in windrows to cure. After about a week or when they have dried thoroughly, the bulbs are topped by cutting off leaves and roots with shears. Diseased and damaged bulbs are sorted out in the field. The bulbs of a variety should be thoroughly sorted and graded. The cloves of garlic variety should be sound and practically free from mould, disease, soil outer skins, stems, leaves and roots as per International Standard ISO-5560: 1997.

   General:  Dehydrated  garlic  shall  conform  to  the  requirement  of  this  International

Standard and on rehydration shall regain characteristics similar to those of fresh garlic.

   Colour: The colour of dehydrated garlic shall be the characteristic of the cultivar used, i.e. between white and pale cream. The product shall be practically free from scorched, toasted and baked particles.

   Odour:  Dehydrated  garlic  after  rehydration  by  the  method  specified  under  the International  Standard  shall  have  a  characteristic,  pungent  odour,  free  from  foreign odour and off odour such as those coming from mouldy, rancid, fermented or burnt particles.

   Flavour:  The  flavour  of  the  dehydrated  garlic  is  assessed  after  rehydration  in accordance with the method specified under the International Standard. It shall be the characteristic of parboiled garlic and free from foreign flavour and off flavour such as those coming from mouldy, rancid, fermented or burnt particles.

   Freedom from insects, moulds, etc.: Dehydrated garlic shall be free from live insects and   practically   free   from   moulds,   dead   insects,   insect   fragments   and   rodent contamination  visible  to  the  naked  eye  or  with  such  magnification  as  may  be necessary  in  any  particular  case.  In  case  of  dispute,  the  contamination  of  garlic  in powder form shall be determined by using the method specified in ISO-1208.

   Extraneous  matter:  The  total  percentage  of  extraneous  matter,  i.e.  vegetable  matter originating  exclusively  from  plants, such  as particles from  skins and  roots shall not exceed 0.5% (m/m).

Table 5    Chemical requirements of dehydrated garlic

Characteristic                                                  Requirement        Test method

Moisture content, % (m/m), max.                     8                          ISO 939

Total ash, % (m/m), on dry basis, max.           5.5                       ISO 928

Acid-insoluble ash, % (m/m) on dry basis, max.                         0.5            ISO 930

Volatile organic sulphur compounds content,  0.3                       ISO 5567

% (m/m) on dry basis, min.

Cold-water-soluble extract, % (m/m) on dry basis,

min.,                                                             70                        ISO 941

max.                                                             90

Dehydrated garlic may be divided into the broad categories given below:

   Dehydrated garlic slices It is a product obtained by cutting garlic cloves into slices and removing broken pieces smaller than 4 mm by sieving.

   Dehydrated garlic flakes or pieces These are the products passing through a sieve of aperture size from 1.25 mm to 4 mm according to the case. The particles do not have any definite shape.

   Dehydrated garlic grits

It is a product passing through a sieve of aperture size 250   m to 1.25 mm.

   Powdered garlic

It  is  a  homogenous  product  95%  of  which  passes  through  a  sieve  of  aperture  size

250   m. Dehydrated  garlic  shall  comply  with  the  requirements  for  chemical  and  physical

properties  specified  in  Table  5  when  tested  by  the  specified  method.  M/s.  Garlico Industries, Mandsaur, Madhya Pradesh, India has also given the specifications of garlic powder as required in the United States (Table 6).

Requirements for sampling are as follows:

   Dehydrated  garlic  powder  or  grits:  Sampling  of  the  product  is  done  in  accordance

Table 6    Specifications of garlic powder

Parameter                                            Standard

Description                                          Off-white/Yellow colour powder

Allicin yield                                        Not less than 12,500 ppm Alliin       Not less than 28,000 ppm Gamma Gluamylcysteins              Not less than 6,000 ppm Total Thiosulphinates        Not less than 13,000 ppm Total Sulphur          Not less than 6,000 ppm Moisture    6% maximum

Granulation                                         +35 Mesh-max. 1%

+45 Mesh-max. 1%

+80 Mesh-max. 15% Total Plate Count        100,000 Cfu/g maximum Mould Content                    1000 Cfu/g maximum E.Coli None Detected Salmonella                                                            None Detected

with ISO 948 using a conical sample or other suitable implement to remove aseptically or representative sample.

   Dehydrated  garlic  slices,  flakes  or  pieces:  Certain  problems  arise  as  a  result  of  the friability  of  the  product  and  the  danger  of  settling  within  the  container.  It  may, therefore, be necessary to take the entire contents of a single container because, during transport,  the  garlic  may  settle  with  the  larger  pieces  towards  the  top  and  smaller pieces towards the bottom.

   Test methods: The samples of dehydrated garlic shall be tested for conformity with the requirement  of  this  International  Standard  by  following  the  methods  of  physical, organoleptic and chemical analysis specified above and in Table 5.

As far as packing and marking are concerned, dehydrated garlic shall be placed in clean, sound and dry containers made of a material which does not affect the product but which protects it from light and from ingress of moisture. The packaging shall also comply with any national legislation relating to environmental protection. The following particulars shall be marked directly on each package or shall be marked on a label attached to the package:

   name of the product, botanical name and trade names, if any;

   name and address of the producer or packer or trademark, if any;

   code or batch number;

   net mass;

   producing country;

   any other information requested by the purchaser, such as year of production and date of packing, if known;

   reference to this International Standard; and

   whether the product contains additives, and if so, which ones, in the case of countries where they are permitted.

Methods of rehydration and sensory evaluation of dehydrated garlic are:

   Garlic  slices:  Vessel,  of  about  500 ml  capacity  made  of  a  material  which  will  not impart a foreign taste or affect the colour of the preparation, dish made of porcelain or white  earthenware  and  stainless  steel  spoon  are  the  apparatus  used  in  rehydration. Natural, potable water as neutral as possible is used. Sample of 10 g ± 0.1 g is weighed and transferred to the vessel containing 500 ml of cold water. It is then boiled at 99sC, keeping the vessel covered for 10 minutes ±1 min. Volume is made up to 500 ml with cold  water  and  then  poured  into  the  dish.  Immediately  then  sensory  evaluation  of appearance of the cooking water (colour and clarity), colour of the preparation, odour, tenderness and flavour is carried out.

   Garlic  powder,  grits,  flakes  or  pieces:  Vessel  of  about  1000 ml  capacity  made  of  a material which will not impart a foreign taste or affect the colour of the preparation, dish  made  of  porcelain  or  white  earthenware,  and  stainless  steel  spoon  are  the apparatus used  in  rehydration.  Flour  made  from  durum  wheat  from  the  most recent harvest and known to be of good quality is used along with natural, potable water as neutral  as  possible  are  used  as  reagents.  1000 ml  of  cold  water  is  transferred  to  the vessel and 30 g of the flour is added while stirring continuously. The mixture is then heated and stirred continuously until it reaches boiling point and then simmered for 2 minutes. Weighing is done to the nearest 0.001 g, 0.4 g of the garlic then placed in the dish.  250 ml  of  the  medium  prepared  is  added  and  allowed  to  stand  for  5  minutes. Stirring  is  done  from  time  to  time.  Sensory  evaluation  is  then  done  for  odour  and flavour.

Table 7    Microbiological characteristics of dehydrated garlic

Characteristic                                      Recommended specification  Test method

M                       M         Microorganisms at 30sC, per gram, max. 105                                                                                                                       106                              ISO 4833

Presumptive Escherichia coli, per gram, max.        10                102  ISO 7251

Yeasts and moulds at 25sC, per gram, max.           103                              104  ISO 7954

Clostridium perfringens, per gram, max.                10                102  ISO 7937

Staphylococcus aureus, in 1 g            Absent                             ISO 6888

Salmonella, in 25 g                             Absent                             ISO 6579

Tests  conducted  in  laboratories  representing  the  producers  and  the  users  of  this product have shown that the microbiological characteristics as given in Table 7 can be considered as acceptable. These are for information only.

Packages  of  dehydrated garlic  should  be  stored  in  covered  premises,  well  protected from the sun, rain and excessive heat. The storeroom should be dry, free from unpleasant odours and protected against the entry of insects and other vermin. While transporting, the  containers  should  be  clearly  marked  with  warning  against  careless  handling  which might lead to perforation of the containers. They should be dry and cool and stored well away from ships’ boilers and bilges.

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