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258 CONFERENCEROCEEDINGS I947these fractions to t he concentrate. It is possible to concentrate th e flavour from five toten times in this way.From this i t is but a step to t he reinforcement of natural flavours by th e addition ofcarefully chosen substances. Su ch reinforced flavours are frequently u sed in tablejellies or chocolate centres. It is, however, no t always possible to use suc h flavouringmaterials, either owing to the unsuitability of the base to be flavoured, as in boiledsweets, or to the fact that the required flavour cannot be obtained from naturalsources. It is the n necessary to em ploy a comp ounde d or synthetic flavour in a suit-able volatile solvent. T h e developm ent of such flavours, which may consist of m ixturesof a considerable num ber of components, is an art similar to th at of th e p erfum er andcalk for considerable skill and experience. To continue the parallel, jus t as the re a regood and crud e perfumes, so there are variations in flavours and correct an d incorrectmethods of using them.

T h e use of ad de d flavour for th e purpose of concealing imperfections cann ot, ofcourse, be too severely condemned, and the lavish splashing in of crude and un-natural flavours is also objectionable, but otherwise there can be no question ofdisapproving of any s tep tha t can add to t he attractiveness a nd palatability of ou r food,an object which has been o ne of mans prime concerns throu gho ut the ages.

T h e author wishes to thank the Directors of J. Lyons and Co. for permission tomake this comm unication.

REFERENCESBarnard,H. . (1911). hem. Engr, 12,104.Bennett, A.H. Donovan, F. K. (1943).Analyst, 68, 140.Power, F.B. & Chesnut, V. K . (1921). . Amer. chem. SOC.3,1741.Stadtman,E.R.,Barker, H. A., Haas, V., Mrak, E. M. & MacKinney, G .(1946). ndustr. Engng Chem.(Industr. ed.), 38, 324.

Nutritional Aspects of the Chemical Preservation, Colouring andFlavouring of Fruit and Vegetables

By L. C. BAKER, . Lyons and Co.Ltd . , Cadby Hall, LondonI propose to deal briefly with the nutritional aspects of the chemical preservation,colouring a nd flavouring of fru it and vegetable products.

Use of preservatives in fru it pulp and fru it drinksFruit preserved for jam-making and o ther purposes by means of sulp hur dioxide

is known as fru it pulp ; for technical reasons it is necessary to ad d a little water as wellas preservative. T h e am oun ts of water a nd preservative adde d are limited by Govern-ment Order S.R. and 0. 1944 to : ( I ) 3 pt. of preservative and 1.25gal. of waterlcwt.of cooked pulp of black currant, red currant, white currant, gooseberry, plum andapple; (2) 3 pt. of preservative and I gal. of water/cwt. of raw pulped strawberry;

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260 CONFERENCEROCEEDINGS I947of each kind of drink but only one sample from most of the other bottles. The resultsfor lemonade syrup I1 and orangeade syrup I show that, as the head-space was increasedby withdrawing samples, the concentration of ascorbic acid decreased on storagewhereas in samples taken from unopened bottles examined at the same time it showedno loss. The orangeade syrup 11, it is true, showed only a slight fall on sampling forthe fourth time, and the lemonade syrup I also showed only a slight fall on samplingfor the seventh time after 88 days.

Table 2 . Retention of ascorbic acid in canned fr ui ts and vegetablesPercentage of ascorbic acid retained

Head-spaceFruit or vegetable

Gooseberries (Keepsake)Gooseberries (Keepsake)Gooseberries (Careless)LoganberriesLoganberriesBlackberries (cultivated)Blackberries (hedge)Peas (Surprise)Peas (Lincoln)Peas (Charles I)Broad beansStringless beansCarrotsParsnipsSprouts

0-5 ml.7 3P80818870626660428161

I 0 0

98

100

25 ml.5765689 47175685943527541354748

45ml.384944667 3565035384638

-

3 03942

In assessing the effect during storage of added preservative on the ascorbic acid infruit products it is necessary to ensure that preservation has been satisfactory and thatthe head-space is as small as possible. The conclusions of the early workers thatsulphur dioxide caused some destruction of ascorbic acid has been criticized on thegrounds that these two conditions were not always satisfied. Allen, Barker Lk Mapson(1943) oted this conclusion with some surprise, because they found that sulphurdioxide helped to preserve the ascorbic acid during the drying of cabbage. Aftera survey of the published work on the subject it is, I think, fair to say that sulphurdioxide causes little, if any, loss of ascorbic acid. At any rate, it is certain that sulphurdioxide, by preventing fermentation, preserves a large proportion of the ascorbicacid in fruit products which would otherwise be totally lost.

Use of sulphur dioxide in the drying of fruits and vegetablesSulphuring, or the burning of sulphur to give an atmosphere of sulphur dioxide

during the drying of fruit, has been practised for a long time to prevent the browndiscoloration which otherwise occurs in peaches, apricots, and other fruits. It hasbeen found that this treatment also helps to preserve vitamin C.

More recently Allen et al. (1943) sed sulphite to preserve ascorbic acid duringthe drying of cabbage, and found that its use gave improved colour retention. T he

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VOl. I The preservation, colouring and jlavouring of foods 261sulphur dioxide was applied by adding crystalline sodium sulphite (Na,SO,. 7H,O)to the scalding water. This neutral salt was used because sulphur dioxide andmetabisulphite are acidic and therefore unsuitable for use with products containing

Table 3 . Effect of storage and of increase in head-space by repeated sampling onthe ascorbic acid content of fruit drinks

(Ascorbic acid mg./xoo 9.)Length of Sample bottlesstorage L(days) A

8 8.8I 4 8.63 0 7'832 8.443 8.044 8.288 8.2I 2 6 . 018 5'934 4.836 4'947 3'680 2'70 12.34 11.78 10'295 3 2'02 7'86 7 4

I 0 7.16 25

103

136 -

--1 -

F Type of drink

- 1 Lemonade syrup I----- I8'2

J-1 1 rangeade syrup I--- \- Orangeade syrup I1-- I

Table 4. Retention of ascorbic acid during different stages of the drying of cabbage,expressed as percentage of that in raw cabbage

(Allen et al. 1943)Fresh cabbage (loo)

Single scald in water735 cabbage '7

I

Liquor Scalded Destroyed50

Dried

ISingle scald )n sulphite

ILiquor Scalded Destkyed57

Dried

35 cabbage 8I

I IDried cabbage Destroyed3 0 20

I IDried cabbage Destroyed48 9

chlorophyll. The shredded cabbage was scalded for 4 min. in one and half times itsweight of boiling water. When 0.22% of crystalline sodium sulphite was added tothe water, the scalded cabbage retained about 200 p.p.m. of SO,, the dried cabbageabout 1500 p.p.m. and the reconstituted cooked cabbage about IOO p.p.m. Table 4

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262 CONFERENCEROCEEDINGS '947summarizes the percentage retention of ascorbic acid in the various stages of thedrying process; it will be seen that the use of sulphite in the scalding liquor resultsin improved retention.I wish to thank the Directors of J. Lyons and Co. for permission to make this

communication.REFERENCES

Adam, W. B. (1941). Ann.Rep, Campden Res. Sta. 1941.Allen, R. J. L., Barker, J. & Mapson, L. W. (1943). J . SOC.hem. Ind., Lond., 6 2 , 145.

The Preservation of Fruit -juice Products, with Special Reference toNutritional Value

By VERNON . S. CHARLEY,. W. Carter and Co . L td ., BristolT h e fruit-juice products w ith which this paper is concerned are all liquids, bu t theirpreservation is effected by various means. So m e straight juices, e.g. apple an d grape,can be filtered to a completely sterile condition; squashes which retain a proportionof th e fruit tissue cannot be filtered, an d mu st be preserved by othe r metho ds; somejuices are particularly vulnerable to flavour alteration by heat and consequentlypasteurization is no t acceptable. I n a review of this natu re only th e salient feature ofeach process can be given. As the preceding papers by Money (1947) and Baker(1947)have given considerable prominence to th e chemical me thod w hich is comm onto th e preservation of both fruit an d vegetables a nd the ir juices, th is paper will con-centrate more especially on other widely used methods.

Na ture of changes occurring in fruit juicesT h e changes which most generally occur in fruit juices in t he u npreserved state

fall in to t he following categories : I ) Yeast a nd bacterial action causing fermentationof norm al or abnorm al type, or acetification; (2)enzyme action, i.e. decomposition ofpectin by naturally occurring enzymes which causes unsightly deposits ; (3) changesdue to interaction of m any of the naturally occurring chemicals in the juice, and tosome extent du e to th e presence of oxygen, which oxidizes flavouring compo unds,ascorbic acid a nd th e s ulp hu r dioxide often ad ded as a preservative.

T h e preservation of these pr od uct s mu st take account of flavour, for this is one ofthe most imp ortan t factors determining th e palatability of a food product. Generallyspeaking, the factors which favour the retention of the true fresh-fruit flavours arethose that tend to ascorbic acid retention.

Preservation of fruit juice produ cts may be examined in three sections. Fru it,being a seasonable an d perishable com mo dity, has to be processed d urin g a restrictedseason and stored, generally in bulk, u ntil needed for bottling or canning. T h is involves