Technical field of the Invention:
The present invention relates to a novel process for cashew cutting and peeling. More particularly, the present invention relates to an eco-friendly, time-saving, non-thermal and non-enzymatic scission of raw cashew nuts using hydroxyl ion radicals and ascorbic acid.

Background of the Invention:
Cashew Anacardium occidentale is a tree in the family Anacardiaceae. Originally native to Northeast Brazil, it is now widely grown in tropical climates for its cashew seeds and cashew apples.The cashew nutshell liquid (CNSL), a byproduct of processing cashew, is mostly composed of anacardic acids (70%), cardol (18%) and cardanol (5%). These acids have been used effectively against tooth abscesses due to their lethality to a wide range of Gram-positive bacteria. Anacardic acid is used in the chemical industry for the production of cardanol, which is used for resins, coatings, and frictional materials.Many parts of the plant are used medicinally. The bark is scraped and soaked overnight or boiled as an antidiarrheal; it also yields a gum used in varnish. Seeds are ground into powders, used as anti-venom for snake bites. The nut oil is used topically as an antifungal and for healing cracked heels.

Presently cashew processing systems have lots of problems such as environmental pollution, health problems to cashew workers (especially women workers); effecting ecological balance, CNSL contamination on the surface of cashew processing units and wastage of a costly foreign exchange earner compound anacardic acid.

The existing cashew processing technology in cashew processing units involves both manual and mechanically operated machinery. In cashew processing unit a big amount of energy is utilized for various operations like, drum roasting, shelling, peeling, grading and sorting as well as steam cooking of raw cashew nuts which are manually done.

The roasting system for raw cashew nuts has been evolved through a number of stages such as sun drying on rock surface, pan roasting, drum roasting, oil bath roasting and steam roasting (Russell, 1969). Presently, the most preferred method is that of steam roasting, where better control on roasting can be applied. The disadvantage of the above mentioned processing system is the decarboxylation of the higher amount of anacardic acid (90%) present in the cashew nut shell. Anacardic acid content (90%) is high in raw cashew nut shell which undergoes decarboxylation to cardanol during the extraction of the shells at high temperature. The shell liquid if obtained by low temperature treatment contains only anacardic acid and cardol with anacardic acid as the major component.

Atmospheric pollution is one of the major problems with drum roasting cashew processing units in India. The cashew processing centre and inhabited areas are contaminated due to heavy fall out of the CNSL and as these phenolic compounds are highly polymerizable, it forms complex with soil and dust and takes the shape of thick mat on the surfaces of the processing ground. This process will cause the health problems due to this compound. The contamination by these phenolic compounds is highly risky both for human health, mainly for women workers as well as for the ecological balance.

The above mentioned problems can be overcome by using a novel process of the present invention. This process could overcome the problems of conventional cashew processing systems in cashew industries. Maintenance of nutritional values in cashew kernels as well as prevention of wastage of anacardic acid through decarboxylation could possible by this newly invented process.

Moreover, in the present processing system there is no energy consumption and it is time-saving. This new process can overcome the health problems in cashew workers.

In short, the drawbacks of the existing prior arts includes high energy utilization, atmospheric pollution, CNSL contamination, decarboxylation of anacardic acid, human health problems and effect on ecological balance need to be overcome by a newer cost-effective and efficient technology that can address the pollution problems of environment and human health by preventing decarboxylation of anacardic acid to avoid CNSL contaminations, thereby maintaining ecological balance and less time consuming.

Some of the Patent related literature which involves processes for peeling of cashew nuts is described as below:-

US Patent No. 3873743 discloses that, the skins of nut meats or kernels are effectively removed by immersing the unpeeled nut in an aqueous acid-surfactant solution to loosen the skin and, thereafter, washing the so-treated kernel, immersing the kernel in a decolorizing bath, and finally polishing the kernel followed by drying.

US Patent No. 2806501 relates to an improved process for the treatment of hard-shelled nuts for the separation of the kernels from the shells thereof and to apparatus for carrying out the process and is particularly applicable to that species of nut in which the shells contain phenol and/or resinous substances such as cashew nuts of the Anacardium group, and Telfairia pedata seeds.

US Publication No. 20050089613 provides edible cashew nuts with intact testa (or skins/husks) remaining on the nut, as well as systems and methods for preparing the same. The process entails reducing levels of inedible chemicals, particularly tannins and polyphenols, contained in cashew testa to render an edible testa-on cashew product. As part of the chemical removal process the edible testa-on cashew products can be infused and/or coated with a variety of spices and flavorings, including, but not limited to salt, sugar, chocolate, honey and/or other edible materials.

The abovementioned prior arts disclose processes for peeling of skins of cashew nut kernels using an aqueous acid-surfactant solution (US’743), kernel separation from shell using thermal energy and pressure utilization (US’ 501) and removing of inedible chemicals from testa on cashew (US’613); whereas in the present invention raw cashew nuts were cut opened within half an hour time using hydroxyl ions, peeling of testa was easy without any treatments and no thermal energy is used for this invention.

In view of the above, an effort has been made to develop an eco-friendly and time-saving technique to cut open raw cashew nut without using thermal energy. Using hydroxyl ion radicals, a non-thermal and non-enzymatic scission of cashew nut shell is possible and thus creating a green healthy atmosphere for cashew workers by introducing a new process. On the processing side, production of better whole kernel recovery is the prime important area.

Hence, it is an object of the present invention to create a green healthy atmosphere for cashew workers in cashew processing industries as well to avoid decarboxylation of anacardic acid present in cashew nut shell by introducing new process for cashew cutting and peeling by the application of hydroxyl ion radicals and ascorbic acid without using thermal energy.

Summary of the Invention:
The present invention provides a novel, eco-friendly, time-saving, non-thermal and non-enzymatic process for cashew nut cutting and peeling using hydroxyl ion radicals and ascorbic acid.

Brief Description of Figures:
Figure 1: Raw Cashew Nut before treatment (On the Left) Raw Cashew Nut Shell Expanded on hydroxyl ions treatment (On the Right).
Figure 2: Expanded Raw Cashew Nut Shell by hydroxyl ions treatment-thereby freeing the Cashew Kernel.
Figure 3: Cell wall loosening of raw cashew nut shell by hydroxyl ion treatment.
Figure 4: Slit opening of harder inner shell of the raw cashew nut by hydroxyl ion treatment.

Detailed Description of the Invention:
The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated. However, any skilled person will appreciate the extent to which such embodiments could be extrapolated in practice.

Source of the material:
Raw cashew nut samples used in the present invention were collected from Cashew Processing Industry, Ayathil, KSCDC, Kollam, Kerala and all the reagents used were analytical reagent grade.

The present invention discloses a novel process for cashew cutting and peeling.

The present invention discloses a novel process which involves eco-friendly, time-saving, non-thermal and non-enzymatic scission of raw cashew nut shell using hydroxyl ion radicals and ascorbic acid in presence or absence of catalyst. If the process is carried out in presence of catalyst, then the catalyst used is preferably Copper (Cu2+).

The precursor of the hydroxyl ion radicals of the present invention includes hydrogen peroxide and ascorbic acid. It is present in the ratio 500:1 of hydrogen peroxide and ascorbic acid respectively for 1 kg of raw cashew nut processing.

The novel process of the present includes two major steps for processing the raw cashew nuts:-
Step 1: Cutting of raw cashew nut shell using hydrogen peroxide: -
In this step, Hydrogen peroxide was treated with ascorbic acid and continuous aeration was given for 3 hrs. with or without catalyst. Raw cashew nut samples were treated with the aerated solution and kept at room temperature, which results in cell wall loosening especially in the outer shell as well as expansion of the inside hard shell of raw cashew nut. Thus shelling made easy.

Step 2: Peeling of testa from cashew kernels:-
In this step, cut opened raw cashew nut samples of step 1 were tested for peeling process by manually as well as cutting machine.

Accordingly, in one preferred embodiment, the present invention provides a process for cutting and peeling of raw cashew nut comprises;
a) Treating hydrogen peroxide with ascorbic acid followed by continuous aeration to obtain aerated solution;
b) treating raw cashew nut with aerated solution of step (a) with or without catalyst and maintaining the same at room temperature for cell wall loosening and expansion of inside hard shell; and
c) partial cut opening of raw cashew nut of step (b) and peeling off cashew kernels manually (by hand);
or

for complete shelling (cut open), drying the raw cashew nut of step (b) at room temperature for 24 hrs. followed by cutting the raw cashew using any cutting machine to remove cashew kernels.

The cell wall loosening in the outer shell as well as expansion of the inside hard shell of raw cashew nut is depicted in Figure 1 to Figure 4.

Using hydroxyl ions, raw cashew nut samples were cut opened within half an hour without using thermal energy. Peeling of testa was also found easy without any treatments. Biochemical characteristics of the newly processed cashew kernel quality were also identified and found it was good as the unprocessed or thermally processed cashew kernels (as shown in Example 2). Hydroxyl radicals (-OH) generated from hydrogen peroxide has been used as a cell wall-loosening agent in cashew shell.

In the present working system, the testa is removed by hand manipulations. One great advantage of this manual peeling process is the grading of cashew kernels taking place simultaneously. The manual operation is practiced since very long period in sorting, roasting, cutting, extraction of kernel from shell, peeling the testa, borma operation and grading is being continued with little bit of modification in introducing cutting machine.

In the mature seeds of most angiosperms, the embryo is covered by two envelopes: the living endosperm and the dead testa. Cell wall loosening is required for radicle elongation growth driven by water uptake and for weakening of the covering envelopes (Bewley, 1997; Finch-Savage and Leubner-Metzger, 2006; Nonogaki, 2006). Loosening of cell walls is an important developmental process in key stages of the plant life cycle. Hydroxyl radicals (-OH) have been proposed as an additional plant cell wall-loosening agent (Schopfer, 2001). These extremely reactive molecules can, if produced directly in the apoplast, attack cell wall polysaccharides and lead to breakage of load-bearing structures. This process has been hypothesized to play a role in a variety of contexts, such as seed germination (Bailly, 2004) and seedling growth (Schopfer, 2001).

Experimental Details:
30% hydrogen peroxide (600 ml) + Ascorbic acid (1g) + Raw cashew nuts (1 kg nuts at a time)
3 hr. continuous aeration
With or without catalyst (Cu2+)

Partial shelling of treated raw cashew nut by hand immediately
OR
Dried at room temperature for 24 hrs

Cut opened raw cashew by any cutting machine

Peeling of cashew kernels by hand

The reaction solutions can be reused for 3 times. The reactions can be catalyzed in-vitro by adding catalase enzyme or Cu2+ ions.

In this reaction, copper effectively acts as a 'catalyst'. The Cu2+ is re-cycled, therefore only minute traces are required to support the continuous production of -OH by ascorbate +O2.

Xyloglucan is a key polysaccharide in primary cell walls, especially of dicots: The presence of only 1 Cu2+ ion per 150 000 sugar residues (i.e., 1 Cu2+ ion per 20-30 xyloglucan molecules of Mr ˜ 106) is enough to sustain an appreciable rate of ascorbate-induced scission of xyloglucan chains (Fry, 1998).

Two hypotheses, which are not mutually exclusive, have been put forward to explain the source of -OH production in the cell wall: natural Fenton reactions dependent on a reductant (e.g. ascorbate), transition metal ions (e.g. copper), and a source of H2O2 (e.g. O2 or O2-) in the cell wall (Fry, 1998); and peroxidase mediated Haber-Weiss reactions (H2O2 + O2-/-OH + OH- + O2; Schopfer, 2001). -OH radicals can attack any polysaccharide (Fry, 1998), although notnecessarily uniformly. If wall-bound Cu2+ is responsible for cell wall loosening during fruitripening, the possible mechanism involved in the addition of ascorbate to the cell walls of cashew shell result in a promotion of polysaccharide chain cleavage [as shown in equations (1)-(4)].
Cu+ + H2O2 . OH + OH- + Cu2+ (1)
4 AH2 + 3 O2 - [Cu2+] 4 A + 4.OH + 2 H2O (2)
(Where AH2 = Ascorbate and A = Dehydroascorbate)

Copper has also been reported to bind to phenolics (possibly 'tannins') in hyphal walls of the fungus Neurospora crassa (Suresh and Subramanyam, 1998); Cashew nut shells are also known to contain diverse phenolics (cardol, cardanol and tannin). Cu2+ in cell walls is of interest because its reduction product; Cu+, can undergo a non-enzymatic 'Fenton reaction with H2O2, producing .OH radicals: -OH radicals can attack any polysaccharide (Fry, 1998), although not necessarily uniformly.

Cu+ + H2O2 . OH + OH- + Cu2+ (1)

The rate constant for this reaction is 4700, M-1 s- 1, which is 60 x greater than that for the corresponding reaction with Fe2+ (Halliwell and Gutteridge, 1990). The two Fenton reactants (Cu+ and H2O2) can both be produced in the apoplast in vivo: the reduction of Cu2+ to Cu+ may be effected non-enzymatically by any of a wide range of electron donors (Davies et al., 1991; Fry, 1998; Ohta et al., 2000; Tabbi et al., 2001). Such electron donors are ascorbate (Burkey, 1999; Takahama, 1993; Zheng et al, 2000), and dehydroascorbate (Burkey, 1999; Takahama 1993) given the probable presence of these two substrates (Cu+ and H2O2), it seems likely that.OH radical production via the non-enzymatic Fenton reaction (Equation (1) occurs in plant cellwalls in vivo.

Ascorbic acid is able non-enzymatically to reduce both Cu2+ to Cu+ and O2 to H2O2. Therefore, in the presence of traces of Cu2+, an aerated solution of ascorbic acid is sufficient to generate .OH radicals via the reactions:
½ AH2 + Cu2+ A + H+ + Cu+ (3)
AH2 +O2 A + H2O2 (4)
(Where AH2 = ascorbate and A = dehydroascorbate)

The result of this experiment showed that the treated raw cashew nut in the aerated solution of hydrogen peroxide after half an hour time could be cut opened manually. Hydroxyl (OH) radicals readily cause the non-enzymatic scission of wall polysaccharides in vitro, including xyloglucan, pectins and mixed-linkage ß- (1 3), (1 4) - glucan (MLG) (Fry, 1998; Tabbi et al., 2001). The peeling of testa from cashew kernels was also found to be easy and successful by hand.

Cashew nut shell liquid (CNSL) can also be separated from fragmented honeycombed cashew shell material without employing thermal techniques. By this newly invented process we can overcome the existing problem such as decarboxylation of anacardic acid and create a green healthy atmosphere for working people in cashew processing industries. Moreover, this process is quick as well as economic and can produce whole kernels with free of cracks. Other advantage of the new process is the adaptability of nuts to the 'Cutting' process of decortification and the recovery of the entire CNSL from the shells.

The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.

Examples:

Example 1: Process for cutting and peeling of raw cashew nut
30% hydrogen peroxide (600ml) was treated with 1g ascorbic acid followed by continuous aeration for 3 hrs. to obtain aerated solution. Raw cashew nut samples (1 Kg nuts at a time) was treated with said aerated solution with or without catalyst (Cu2+) and maintaining the same at room temperature for cell wall loosening and expansion of inside hard shell. Cut opened the raw cashew nut samples and peel off the cashew kernels manually or drying the raw cashew nut samples at room temperature for 24 hrs. and cutting with any cutting machine to remove cashew kernels.

Example 2: Comparison of Newly Processed Cashew Kernels and Anacardic Acid Content
Analysis Newly Processed Un Processed Thermal Processed
Colour White White Off white
Smell Good Good Good
Taste Good Good Good
Moisture (%) 4 8 3.8
Carbohydrates (%) 23 24.62 21.4
Protein (%) 15.73 17.12 13.9
Fat (%) 46 43 36
Anacardic acid 77.67% 77.67% 55.16% (Only from
steam cooking)

2241/DEL/2014