Composition for extending shelf life of fruits and vegetables

A composition for reducing deterioration and extending the shelf life of fruits and vegetables, particularly fruits and vegetables used in salad bars and prepared salads sold in fast-food restaurants, comprising ascorbic acid and a thixotropic gum such as xanthan. Optionally, other ingredients such as an edible bulk filler and artificial or natural flavorings and/or aromas colorings may also be added. The composition applied to the salad ingredients to extend shelf life is advantageous in that a salad preserving agent is provided which is well retained by the salad ingredients so as to maintain freshness of the salad for long periods of time, and the extended shelf life provided is accomplished without sulfites and without adding any objectionable gummy mouthfeel to the product.

FIELD OF THE INVENTION 
This invention relates to a sulfite-free composition for minimizing 
discoloration and extending shelf life of foods, particularly fruits and 
vegetables, more particularly to a preservation composition comprising an 
organic food acid and a thixotropic gum, and to the use of such 
compositions for those purposes. For salads a combination of xanthan gum 
alone or combined with other thioxotropic gums and ascorbic acid alone or 
in combination with other organic acids is particularly preferred. It is 
also highly desirable to add aroma and or flavor compounds to enhance the 
salad flavor. 
BACKGROUND OF THE INVENTION 
It has recently become extremely popular for restaurants, fast-food 
establishments, and even supermarkets to Provide salad bars wherein 
patrons can prepare their own salads from freshly cut vegetables and 
fruits. However, these various salad ingredients will show physical signs 
of deterioration, such as wilting, drying, shrinking or browning, within a 
fairly short time period. After such physical deterioration, these fruits 
and vegetables are no longer marketable. In addition, certain fast-food 
restaurants now offer ready-made salads which are prepared and 
refrigerated, but these too must be discarded if not purchased after a 
certain period of time. Although the problem of preservation of fresh 
fruits and vegetables has been with us since these products were first 
marketed, the problem is a particularly marked one at present due to the 
great prevalence of freshly cut produce in salad bars and prepared, 
containered salads which have extremely short shelf lives. 
Many attempts have been made over the years to combat the problems of 
browning, wilting, etc. in cut or whole fruit and vegetable matter. 
Various methods and compositions have been invented for combatting 
oxidative deterioration in these products, such as described in U.S. Pat. 
Nos. 4,140,649; 3,987,208; 3,814,820; and 3,533,510. In these patents, 
active agents disclosed for use in preventing deterioration include 
ascorbic acid, other edible acids, and other sulfites, sodium phosphates, 
sodium ascorbate, and potassium sorbate. Dry treatment with CMC and 
optional gums including locust bean, guar, carragaum, tragacanth, 
alginates, acacia, bentonite and agar have been used with fruit acids as a 
dry treatment for fruits to preserve them during heat treatment. It is 
highly desirable to develop a fruit or vegetable salad preservative which 
does not contain sulfites, yet which can be used effectively to prolong 
shelf life particularly for salad bar ingredients and pre-prepared salads. 
It is also desirable to develop a salad preservative which does not add 
any objectionable slimy, gummy or heavy mouthfeel to the salad 
ingredients. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a composition is provided for 
reducing deterioration and extending shelf life of fruits and vegetables 
which comprises edible organic acid preferably ascorbic acid and an edible 
thixotropic gum, preferably xanthan. The composition of the present 
invention is preferably used on salad bar ingredients and in prepared 
salads so as to ensure freshness, without adding an objectionable gummy 
mouthfeel to the salad and without the use of sulfites. The composition 
can also include a bulk filling agent, such as maltodextrin, and natural 
or artificial flavorings and/or aromas, and is applied as an aqueous 
solution.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In accordance with the present invention, a composition which extends the 
shelf life of salad ingredients is provided which comprises an edible 
organic acid active ingredient and an edible thixotropic gum. It is 
particularly preferred that the thixotropic gum employed in the present 
invention comprises xanthan gum which provides a sheer thinning, non-slimy 
mouth feel. However, many other suitable gums can be used, at least in 
part, including guar gum, gum tragacanth, carrageenan gum, alginate gum, 
and karaya gum all which give sheer thinning properties but are less 
desirable due to their slimy mouth feel. The composition of the present 
invention also includes food grade organic acids to prevent discoloration. 
Preferred are ascorbic acid or isoascorbic acid alone or combined with 
other acids. Other useful food grade organic acids are citric acid, 
fumaric acid, tartaric acid, malic acid and the like. Where acidity can be 
tolerated, these acids, particularly citric, could be used alone although 
it is preferred to include ascorbic acid. Other active antidiscoloration 
agents, such as cysteine, can be used to replace all or part of the 
organic acid but are less desirable because of cost and taste. 
In the preferred embodiment, the ratio by weight of the antidiscoloration 
acid to the edible thixotropic gum in the composition will range from 
about 1:1 to about 30:1, with a range of from about 3:1 to about 5:1 
preferred for the antidiscoloration acids. The composition of the present 
invention is extremely effective in extending the short shelf life of 
fresh vegetables and salads, particularly in the case of ingredients 
prepared for salad bars and over-the-counter prepared salads. The 
composition of the present invention is successful in retaining freshness 
in such salad ingredients without the use of sulfites, and for longer 
periods of time than previously achievable. 
Another application of this composition is a wash in preparing fruits and 
vegetables for drying. 
The composition of the present invention will primarily comprise food grade 
ascorbic acid and food grade edible xanthan gum, but can also include a 
food grade bulk filler, such as maltodextrin. Other conventional 
ingredients such as flavoring and aroma agents and coloring agents may 
also be included. In general, where a bulk filler is employed, the ratio 
by weight of the bulk filling agent to the ascorbic acid will range 
roughly from 0.1:1 to 10:1, and preferably 0.3:1 to 3:1, and, most 
preferably, this range will be from about 0.666 to about 1.50:1. 
It is preferred that the bulk filler used be maltodextrin, particularly low 
D.E. maltodextrin. The maltodextrin is preferably employed in the form of 
expanded low density maltodextrin. 
A typical composition of the invention will contain the following 
ingredients by percentage of the total weight of the solid ingredients 
(dry basis): 
(a) 20-60% edible bulk filler (e.g., maltodextrin) 
(b) 20-60% ascorbic acid 
(c) 1-50% edible xanthan gum. 
The solid ingredients are dissolved in water prior to use although a liquid 
or aqueous concentrate may be prepared and diluted before use. A bulk 
filler improves the consistency of the aqueous solution and the wetability 
of the dry mix. In the composition of the invention, any conventional 
readily available food grade ascorbic acid can be employed. Generally, the 
ascorbic acid should comprise about 20-60% by weight, more preferably 
25-50%, of the total weight of the solid ingredients of the composition. 
A wide variety of natural and artificial flavoring and/or aromatizing 
agents can be used in the composition. These agents can be added to the 
composition comprising edible organic acid and the edible thixotropic gum 
alone, or can be added to compositions which include a bulk filling agent 
as well. In general, the flavoring and/or aromatizing agents will be 
employed in a ratio by weight to the ascorbic acid ranging from about 
0.05:1 to about 1:1, with a range of about 0.1:1 to about 0.4:1 
particularly preferred. A typical composition of the invention employing a 
flavoring agent and a bulk filling agent will contain the following 
ingredients (by weight percentage of the total weight of the solid 
ingredients): 
(a) 20-60% edible bulk filler (e.g., maltodextrin) 
(b) 20-60% edible organic acid (e.g., ascorbic acid and/or citric acid) 
(c) 1-50% edible thixotroPic gum (e.g., xanthan and/or other shear thinning 
thixotropic gums). 
(d) 1-25% natural or artificial flavoring and/or aroma agent. 
An example of a natural flavor and/or aroma usable in the present invention 
is leaf essence, produced by General Foods, particularly useful with 
regard to compositions designed to be added to salad ingredients. 
Artificial lettuce flavoring agents are particularly useful in salads. Any 
suitable natural or artificial flavor or aroma, however, which is 
appropriate for a particular application can be used in the invention. 
With regard to the gums usable in the present invention, it is generally 
preferred that a food grade thixotropic gum be employed in an amount 
ranging from about 1 to about 50% by weight of the total weight of the 
solid ingredients in the composition, depending on the particular gum 
chosen. Preferably, the gum should be used at a level of 1-25%, more 
particularly from 2-20%, and more preferably should comprise about 4-12% 
of the composition. It is necessary that the gums employed in the 
invention be used at these low percentages because when used at higher 
levels, particularly above 50%, they can add an objectionable mouthfeel to 
the product and reduce organoleptic acceptability. The composition of the 
present invention prevents the discoloration of salad ingredients yet does 
not add objectionable gummy qualities to the salad. It also retards 
wilting, drying, and deterioration of the salad. It is thus particularly 
important to use proportions of thixotropic gums as stated above to ensure 
that the salad ingredients treated maintain organoleptic acceptability. 
In preparing the compositions of this invention it is preferable that a 
major amount of the edible organic acid comprises ascorbic acid, 
isoascorbic acid and mixtures thereof and, in addition, it is preferable 
that a major amount of the thixotropic gum comprise xanthan gum. 
The composition of the present invention is preferably applied to whole or 
cut fruits, vegetables, or other salad ingredients in the form of an 
aqueous solution. The term "solution" is used in a general sense to 
include compositions in which one or more of the ingredients is not in 
true solution. Food grade co-solvents may be employed to facilitate 
dispersion of ingredients that are not readily dissolved in water. The 
solution containing the composition can be applied in any convenient and 
effective manner, such as spraying, dipping, by drops, etc. Ideally, a 
light spray of the preserving solution over a tray or platter of salad 
ingredients will be sufficient to apply an effective amount of the 
composition to the salad. By effective amount is meant that amount 
necessary to extend the shelf life of the fruit or vegetable ingredient 
treated. This amount will be in the range of from about 0.1% to 10% by 
weight of solid ingredients based on the weight of the salad treated, and 
preferably about 0.2% to 4%. 
For individual active agents, the effective amount of thixotropic gum in 
solution needed to adhere the active ingredient or acid to the salad 
ingredients would range from 0.01% to 5% by weight of the solution, 
preferably from 0.01% to 2% by weight of the solution. In a similar manner 
the effective amount of organic acid needed to retard discoloration and 
improve storage ranges from 0.01% to 5% acid, preferably ascorbic, by 
weight of the solution, preferably from 0.01% to 2% by weight of the 
solution. 
Generally, effective aqueous solutions containing the composition of the 
present invention can be prepared having a total solids concentration of 
roughly from about 10 to 50 g/l of solution, preferably about 20 to 30 
g/l. An example of such a solution is the following: 
______________________________________ 
LOW D.E. maltodextrin 50 grams 
Ascorbic acid 50 grams 
Natural vegetable flavor 
15 grams 
Xanthan gum 10 grams 
Water to 5 liters 
______________________________________ 
Such a solution can be used to treat at least 50 pounds of salad 
vegetables, or approximately about 100 small individual salad servings, 
without adding significantly to the cost of an individual salad. In tests 
on various salads, the agueous solution formed using the composition of 
the present invention is able to prevent discoloration, wilting, and 
drying for long periods of time, thus extending the shelf life of the 
fruit and vegetable salad ingredients. It is clear that the composition of 
the present invention can provide an inexpensive, efficient and simple 
means to extend the shelf life of over-the-counter prepared salads or 
salad bar items, without adding sulfites, objectionable tastes, or gummy 
mouthfeel. 
The following examples are presented as illustrative of the present 
invention and are not intended to limit its scope in any way: 
EXAMPLE 1 
Various tests are made with regard to the abilities of particular compounds 
to prevent deterioration and extend the shelf life of salads. Tests 
involve the use of solutions with ascorbic acid, xanthan gum, fresh 
lettuce flavor, water, or combinations of these ingredients. Three 
solutions are composed by weight percentages as follows: 
______________________________________ 
Solution 1: Water 100% 
Solution 2: Ascorbic acid 
1.0% 
Xanthan Gum 
0.2% 
Water 98.8% 
Solution 3: Ascorbic acid 
1.0% 
Xanthan Gum 
0.2 
fresh lettuce 
0.1% 
flavor 
Water 98.7% 
______________________________________ 
Salads are prepared using fresh cut vegetables including lettuce, tomatoes, 
cucumbers, peppers and radishes. The solutions described above are applied 
to the salad ingredients by dipping the food in the solutions, and 
afterwards the salads were stored in the refrigerator in 5-ounce salad 
dishes with lids. After days, observations are as follows: 
(a) Salad treated with Solution 1 (water only): 
Lettuce: Good, but dry, mealy, slightly brown and shriveled. 
Tomato: Dry and shriveled. 
Cucumber: Dry, shriveled and mealy. 
Pepper: Dry, shriveled and mealy. 
Radish: Dry, shriveled and mealy. 
(b) Salad treated with Solution 2 (Ascorbic acid and xanthan): 
Lettuce: Better than control; crisp and moist. 
Tomato: Better than control; crisp and moist. 
Cucumber: Better than control; crisp and moist. 
Pepper: Better than control; crisp and moist. 
Radish: Best condition of series, excellent condition. 
Overall condition: Acceptable for sale. 
(c) Salad treated with Solution 3 (Ascorbic acid, xanthan and flavor): 
Lettuce: Best condition of series; crisp and moist. 
Tomato: Best condition of series; crisp and moist. 
Cucumber: Best condition of series; crisp and moist. 
Pepper: Best condition of series; crisp and moist. 
Radish: Very good condition; crisp and moist. 
Overall condition: Best overall, acceptable for sale. 
The various solutions employing ascorbic acid and xanthan gum are thus 
observed to have excellent results in extending the shelf life of salads. 
On opening the salad containers treated with solution 3 the flavor and/or 
aroma enhancement added to the overall quality observed. Obviously, 
individual salad ingredients can be treated with specific effective active 
ingredients to maximize the quality of each individual salad ingredient. 
EXAMPLE 2 
An aqueous solution made from the composition of the present invention is 
tested to determine its ability of preserving the freshness and extending 
the shelf life of fruit salad. Cups of fruit salad are prepared comprised 
of 1/4 inch irregular cubes of peeled and cut (fresh) Granny Smith apples, 
whole de-stemmed fresh red seedless grapes, canned mandarin orange 
sections and canned pineapple chunks. Half of this fruit salad is treated 
by dipping the cut fruit in a solution of 0.95% ascorbic acid, 0.20% 
xanthan gum, 0.95% low density maltodextrin, and 97.9% water. The other 
half of the fruit salad is dipped only in water. The fruit salad is placed 
in 5-ounce salad dishes with lids and stored in a refrigerator. The 
observations are as follows: 
______________________________________ 
Time of 
Placement in 
Control Salad with 
refrigerator 
(Water Only) Solution Applied 
______________________________________ 
0 days Fresh; good, clean. 
Fresh; good, clean. 
refrigeration 
2 days Moldy grapes, Brown 
Fresh; good, clean. 
refrigeration 
apples. 
4 days Moldy grapes; Brown, 
Fresh; good, clean. 
refrigeration 
moldy apples; Apples 
dry. 
8 days Moldy grapes; Very 
Moldy grapes; All 
refrigeration 
brown, moldy applies; 
else fresh. 
apples; Apples dry and 
shriveling. 
______________________________________ 
The solution employing a composition of the present invention is thus 
successfully used to extend the shelf life of fruit salads. Obviously, the 
stability extension of the grapes beyond four days could be achieved by 
the addition of an antimicrobial active agent to the composition or by 
treatment of the grapes separately. 
EXAMPLE 3 
A composition according to the present invention is produced using the 
following ingredients: 
______________________________________ 
INGREDIENT WEIGHT 
______________________________________ 
Low density 50 gms (40%) 
Maltodextrin, 
L-Ascorbic Acid 50 gms (40%) 
Natural Vegetable 
15 gms (12%) 
Flavor 
Leaf Essence G.F. 
Xanthan Gum, 10 gms (8%) 
TOTAL 125 gms 
______________________________________ 
The above solid ingredients are dissolved in 5 liters of water (11 pounds) 
and the solution is used to treat 50 pounds of salad vegetables 
(corresponding to about 100 individual salad servings). The solution 
prepared was successful and inexpensively extended the shelf life of 
various prepared salads. 
EXAMPLE 4 
A composition according to the present invention is produced as follows: 
______________________________________ 
INGREDIENT WEIGHT 
______________________________________ 
Low density 50 gms (40%) 
Maltodextrin, 
L-Ascorbic Acid 
50 gms (40%) 
Artificial 15 gms (12%) 
Lettuce Flavor 
Xanthan Gum, 10 gms (88%) 
TOTAL 12 gms 
______________________________________ 
The above composition is dissolved in 5 liters of water and is used to 
treat 50 pounds of salad vegetables, at even less expense than the 
composition described in Example 3. The composition is successful in 
extending the shelf life of the individual salad servings.