<PAGE>

THE WARRANTS REPRESENTED BY THIS CERTIFICATE AND THE SECURITIES ISSUABLE UPON
EXERCISE THEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "ACT"), AND MAY NOT BE OFFERED OR SOLD EXCEPT (i) PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT, (ii) TO THE EXTENT APPLICABLE,
PURSUANT TO RULES 701 AND 144 UNDER SUCH ACT (OR ANY SIMILAR RULE UNDER SUCH ACT
RELATING TO THE DISPOSITION OF SECURITIES), OR (iii) UPON THE DELIVERY BY THE
HOLDER TO THE COMPANY OF AN OPINION OF COUNSEL, REASONABLY SATISFACTORY TO
COUNSEL FOR THE ISSUER, STATING THAT AN EXEMPTION FROM REGISTRATION UNDER SUCH
ACT IS AVAILABLE.  THE HOLDER HEREOF MAY NOT ENGAGE IN HEDGING TRANSACTIONS WITH
REGARD TO SUCH SECURITIES UNLESS IN COMPLIANCE WITH THE ACT. 

THE TRANSFER OR EXCHANGE OF THE WARRANTS REPRESENTED BY THIS CERTIFICATE IS
RESTRICTED IN ACCORDANCE HEREWITH.
                                          
                             Warrant to Purchase up to
                          1,000,000 Shares of Common Stock
                                of The RiceX Company


          WHEREAS, reference is made to the Subscription Agreement dated
September 10, 1998 in which The RiceX Company (the "Company") sold and Heldomo,
A.G. ("Investor") purchased 15 Units, each Unit consisting of 66,666.7 shares of
Common Stock and a Warrant to Purchase 66,666.7 shares of Common Stock (the
"Subscription Agreement"); and  

          WHEREAS, this Warrant shall represent the Warrants referenced in the
Subscription Agreement.            

          NOW, THEREFORE, the parties agree as follows:

          1.   Grant.  

          On the terms and subject to the conditions set forth herein, Investor
is hereby granted the right to purchase, at any time during the Exercise Period
(as hereinafter defined) up to 1,000,000 shares of Common Stock (the "Warrant
Shares") of the Company at the Exercise Price (as defined below and as subject
to adjustment as provided in Article 5 hereof). 


          2.   Exercise of Warrant.  
<PAGE>

          2.1  EXERCISE PERIOD.  This warrant is exercisable at any time during
the two (2) year period beginning on the date hereof (the "Exercise Period").

          2.2  EXERCISE.  The Warrant may be exercised by payment of the
Exercise Price in cash or by check to the order of the Company, or any
combination of cash or check.  Upon surrender of the Warrant Certificate with
the annexed Election to Purchase duly executed, together with payment of the
Exercise Price (as hereinafter defined) for the Warrant Shares purchased, at the
Company's principal offices, Investor (or other registered holder(s) of the
Warrant Certificate) (the "Holder") shall be entitled to receive a certificate
or certificates for the Warrant Shares so purchased.  The purchase rights
represented by this Warrant are exercisable at the option of the Holder, in
whole or in part (but not as to fractional Warrant Shares).  In the case of the
purchase of less than all the Warrant Shares purchasable under this Warrant, the
Company shall cancel said Warrant upon the surrender thereof and shall execute
and deliver a new Warrant of like tenor for the balance of the Warrant Shares
purchasable thereunder.

          2.3  ISSUANCE OF CERTIFICATES.  Upon the exercise of this Warrant
pursuant to Section 2.2 above, the issuance of certificates for the Warrant
Shares purchased shall be made forthwith (and in any event within three business
days thereafter) without charge to the Holder thereof including, without
limitation, any tax which may be payable in respect of the issuance thereof, and
such certificates shall (subject to the provisions of Article 4 hereof) be
issued in the name of, or in such names as may be directed by, the Holder
thereof; provided, however, that the Company shall not be required to pay any
tax which may be payable in respect of any transfer involved in the issuance and
delivery of any such certificates in a name other than that of the Holder and
the Company shall not be required to issue or deliver such certificates unless
or until the person or persons requesting the issuance thereof shall have paid
to the Company the amount of such tax or shall have established to the
satisfaction of the Company that such tax has been paid.

          Upon exercise, in part or in whole, of this Warrant, certificates
representing the Warrant Shares shall bear a legend substantially similar to the
following:

          "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE
          NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
          AS AMENDED (THE "ACT"), AND MAY NOT BE OFFERED OR SOLD
          EXCEPT (I) PURSUANT TO AN EFFECTIVE REGISTRATION
          STATEMENT UNDER THE ACT, (II) TO THE EXTENT APPLICABLE,
          PURSUANT TO RULE 144 UNDER THE ACT (OR ANY SIMILAR RULE
          UNDER SUCH ACT RELATING TO THE DISPOSITION OF
          SECURITIES), OR (III) UPON THE DELIVERY BY THE HOLDER
          TO THE COMPANY OF AN OPINION OF COUNSEL, 


                                        2
<PAGE>

          REASONABLY SATISFACTORY TO THE ISSUER, STATING THAT AN EXEMPTION
          FROM REGISTRATION UNDER SUCH ACT IS AVAILABLE."


          3.   Restriction on Transfer of Warrants.  

          Investor, by its acceptance hereof, covenants and agrees that this
Warrant is being acquired as an investment and not with a view to the
distribution thereof, and that neither this Warrant nor, if exercised, any
Warrant Shares, may be offered or sold except (i) pursuant to an effective
registration statement under the Act, (ii) to the extent applicable, pursuant to
Rule144 under the Act (or any similar rule under such Act relating to the
disposition of securities), or (iii) upon the delivery by the Holder to the
Company of an opinion of counsel, reasonably satisfactory to the issuer, stating
that an exemption from registration under such Act is available. 

          Initial and Adjusted Exercise Price.  

          The initial exercise price of this Warrant per Warrant Share shall be
equal to $1.50 for the first year from the date of this Warrant and at an
exercise price of  $1.8125 thereafter. The adjusted exercise price shall be the
price which shall result from time to time from any and all adjustments of the
initial exercise price in accordance with the provisions of Article 5 hereof.

          4.1  EXERCISE PRICE.  The term "Exercise Price" herein shall mean the
initial exercise price or the adjusted exercise price, depending upon the
context.

          5.   Adjustments of Exercise Price and Number of Warrant Shares.

          5.1  PRICE PROTECTION ADJUSTMENT.  In the event that the Company,
prior to the expiration of this Warrant, issues shares of Common Stock (or
options or warrants to purchase shares of Common Stock) for a consideration per
share (or exercise price) less than $1.50 ("Lower Price"), the Exercise Price
shall be adjusted to the Lower Price (the "Price Protection Adjustment").  

          5.2  STOCK SPLIT, STOCK DIVIDEND, SUBDIVISION AND COMBINATION.  In
case the Company shall at any time subdivide or combine the outstanding shares
of Common Stock (including by way of a stock dividend), the Exercise Price shall
forthwith be proportionately decreased in the case of subdivision or increased
in the case of combination.  Upon each adjustment of the Exercise Price pursuant
to the provisions of this Section 5.2, the number of Warrant Shares issuable
upon the exercise of this Warrant shall be adjusted to the nearest full Warrant
Share by multiplying a number equal to the Exercise Price in effect immediately
prior to such adjustment by the 


                                          3
<PAGE>

number of Warrant Shares issuable upon exercise of the Warrant immediately prior
to such adjustment and dividing the product so obtained by the adjusted Exercise
Price.

          5.3  RECLASSIFICATION, CONSOLIDATION, MERGER, ETC.  In case of any
reclassification or change of the outstanding shares of Common Stock (other than
a change in par value to no par value, or from no par value to par value, or as
a result of a subdivision or combination), or in the case of any consolidation
of the Company with, or merger of the Company into, another corporation (other
than a consolidation or merger in which the Company is the surviving corporation
and which does not result in any reclassification or change of the outstanding
shares of Common Stock, except a change as a result of a subdivision or
combination of such shares or a change in par value, as aforesaid), or in the
case of a sale or conveyance to another corporation of the property of the
Company as an entirety, the Holder shall thereafter have the right to purchase
the kind and number of shares of stock and other securities and property
receivable upon such reclassification, change, consolidation, merger, sale or
conveyance as if the Holder were the owners of the Warrant Shares underlying the
Warrant at a price equal to the product of (x) the number of shares of Common
Stock issuable upon conversion of the Warrant Shares and (y) the Exercise Price
prior to the record date for such reclassification, change, consolidation,
merger, sale or conveyance as if such Holder had exercised the Warrant.

          5.4  REDEMPTION OF WARRANT; REDEMPTION OF WARRANT SHARES. 
Notwithstanding anything to the contrary contained in the Warrant or elsewhere,
the Warrant cannot be redeemed by the Company under any circumstances.

          5.5  DIVIDENDS AND OTHER DISTRIBUTIONS WITH RESPECT TO OUTSTANDING
SECURITIES.  In the event that the Company shall at any time prior to the
exercise of the Warrant declare a dividend (other than a dividend consisting
solely of shares of Common Stock (which shall be governed by Section 5.2) or a
cash dividend or distribution payable out of current or retained earnings) or
otherwise distribute to its shareholders any monies, assets, property, rights,
evidences of indebtedness, securities (other than shares of Common Stock),
whether issued by the Company or by another person or entity, or any other thing
of value, the Holder of the Warrant shall thereafter be entitled, in addition to
the securities receivable upon the exercise thereof, to receive, upon the
exercise of such Warrant, the same monies, property, assets, rights, evidences
of indebtedness, securities or any other thing of value that he would have been
entitled to receive at the time of such dividend or distribution.  At the time
of any such dividend or distribution, the Company shall make appropriate
reserves to ensure the timely performance of the provisions of this Section 5.5.

          5.6  SUBSCRIPTION RIGHTS FOR SHARES OF COMMON STOCK OR OTHER
SECURITIES.  In the case that the Company or an affiliate of the Company shall
at any time after the date hereof and prior to the exercise of the Warrant issue
any rights to 


                                          4
<PAGE>

subscribe for shares of Common Stock or any other securities of the Company or
of such affiliate to all the shareholders of the Company, the Holder of the
unexercised Warrant shall be entitled, in addition to the securities receivable
upon the exercise of the Warrant, to receive such rights at the time such rights
are distributed to the other shareholders of the Company.

          6.   Exchange and Replacement of Warrant Certificates.

          This Warrant is exchangeable without expense, upon the surrender
hereof by the registered Holder at the principal executive office of the
Company, for a new Warrant Certificate of like tenor and date representing in
the aggregate the right to purchase the same number of Warrant Shares in such
denominations as shall be designated by the Holder thereof at the time of such
surrender.

          Upon receipt by the Company of evidence reasonably satisfactory to it
of the loss, theft, destruction or mutilation of the Warrant Certificate, and,
in case of loss, theft or destruction, of indemnity or security reasonably
satisfactory to it, and reimbursement to the Company of all reasonable expenses
incidental thereto, and upon surrender and cancellation of the Warrant, if
mutilated, the Company will make and deliver a new Warrant Certificate of like
tenor, in lieu thereof.

          7.   Elimination of Fractional Interests.

          The Company shall not be required to issue certificates representing
fractions of Warrant Shares upon the exercise of the Warrant, nor shall it be
required to issue scrip or pay cash in lieu of fractional interests, it being
the intent of the parties that all fractional interests shall be eliminated by
rounding any fraction up to the nearest whole number of Warrant Shares.

          8.   Reservation and Listing of Securities.

          The Company shall at all times reserve and keep available out of its
authorized shares of Common Stock, solely for the purpose of issuance upon the
exercise of the Warrant, such number of shares of Common Stock (or other
securities) as shall be issuable upon such exercise or conversion, as the case
may be.  The Company covenants and agrees that, upon exercise of the Warrant and
payment of the Exercise Price therefor (if a cash exercise), all shares of
Common Stock issuable upon such exercise shall be duly and validly issued, fully
paid, non-assessable and not subject to the preemptive rights of any
shareholder.
          
          
                                          5
<PAGE>

          9.   Notices to Warrant Holder.

          If, at any time prior to the expiration of the Warrants and their
exercise, any of the following events shall occur:

          (a)  the Company shall take a record of the holders of its shares of
Common Stock for the purpose of entitling them to receive a dividend or
distribution payable otherwise than in cash, or a cash dividend or distribution
payable otherwise than out of current or retained earnings, as indicated by the
accounting treatment of such dividend or distribution on the books of the
Company; or

          (b)  the Company shall offer to all the holders of its Common Stock
any additional shares of Common Stock of the Company or securities convertible
into or exchangeable for shares of Common Stock of the Company, or any option,
right or warrant to subscribe therefor; or

          (c)  a dissolution, liquidation or winding up of the Company (other
than in connection with a consolidation or merger) or a sale of all or
substantially all of its property, assets and business as an entirety shall be
proposed;

then, in any one or more of said events, the Company shall give written notice
to the Holder of such event at least fifteen (15) days prior to the date fixed
as a record date or the date of closing the transfer books for the determination
of the shareholders entitled to such dividend, distribution, convertible or
exchangeable securities or subscription rights, options or warrants, or entitled
to vote on such proposed dissolution, liquidation, winding up or sale.  Such
notice shall specify such record date or the date of closing the transfer books,
as the case may be.  Failure to give such notice or any defect therein shall not
affect the validity of any action taken in connection with the declaration or
payment of any such dividend or distribution, or the issuance of any convertible
or exchangeable securities or subscription rights, options or warrants, or any
proposed dissolution, liquidation, winding up or sale.

          10.  Notices.

          All notices, requests, consents and other communications hereunder
shall be in writing and shall be deemed to have been duly made when delivered,
or mailed by registered or certified mail, return receipt requested:

          (a)  If to the registered Holder of the Warrant, to the address of
such Holder as shown on the books of the Company; or

          (b)  If to the Company, to the address set forth on the signature page
of this Warrant or to such other address as the Company may designate by notice
to the Holder.


                                          6
<PAGE>

          11.  Successors.

          All the covenants and provisions of this Agreement by or for the
benefit of the Company and the Holder inure to the benefit of their respective
successors and assigns hereunder.

          12.  Governing Law.

          This Warrant shall be deemed to be a contract made under the laws of
the State of California and for all purposes shall be construed in accordance
with the laws of said State.

          13.  Counterparts.

          This Warrant may be executed in any number of counterparts and each of
such counterparts shall for all purposes be deemed to be an original, and such
counterparts shall together constitute but one and the same instrument.


                                          7
<PAGE>

          IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed under its corporate seal.

Dated:  September 10, 1998         THE RICEX COMPANY 



[SEAL]                             By:    /s/ Allen J. Simon
                                      --------------------------------
                                   Name:   Allen J. Simon
                                   Title:  Chief Executive Officer
Attest:

  /s/  Karen D. Berriman   
------------------------
Secretary

ACCEPTED BY AND AGREED TO:

HELDOMO, A.G.



     
/s/ Dr. Jur. Hans Rudolf Barth   
------------------------------
By:  Dr. Barth
Its: Director


                                          8
<PAGE>

                                ELECTION TO PURCHASE

          The undersigned hereby irrevocably elects to exercise the right, 
represented by this Warrant, to purchase _________ shares of Common Stock of 
The RiceX Company (or its successor) and herewith tenders in payment for such 
shares cash or a check payable to the order of The RiceX Company in the 
amount of $______________, all in accordance with the terms hereof.  The 
undersigned requests that a certificate for such shares be registered in the 
name of ___________________, whose address is _______________________________
________, and that such Certificate be delivered to _______________________, 
whose address is ________________________________________________.

Dated:                       Signature:                         
      --------------------             --------------------------------

                              (Signature must conform in all respects to name of
                              holder as specified on the face of the Warrant
                              Certificate.)



                                          
                          --------------------------------


                          --------------------------------
                          (Insert Social Security or Other
                           Identifying Number of Holder)


                                          9
<PAGE>

                                [FORM OF ASSIGNMENT]
                                          
              (To be executed by the registered holder if such holder
                   desires to transfer the Warrant Certificate.)


          FOR VALUE RECEIVED ____________________________________ hereby sells,
assigns and transfers unto _____________________________________________(Please
print name and address of transferee) this Warrant [or a portion of this Warrant
equal to ____________ shares of Common Stock], together with all right, title
and interest therein, and does hereby irrevocably constitute and appoint
_______________, Attorney, to transfer the within Warrant Certificate on the
books of the within-named Company, with full power of substitution.



Dated:                        Signature:                              
      --------------------             --------------------------------

                                   (Signature must conform in all respects to
                                   name of holder as specified on the face of
                                   the Warrant Certificate)



-------------------------------


-------------------------------
(Insert Social Security or Other
Identifying Number of Assignee)


                                          10