Eff’ect of Light on Bottled Juices Apple arid Kraut Juices D. C . CARPENTER, hew York S t a t e Agricultural Experiment Stalion, Geneva, N. Y.
EVEKAGEY are marketed alniost exclusively iii glass
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Many of the foregoing iiivestigatioiis liave little or no application to the problem of suitable glass containers, on account of the fact that the effect of light in the ultra-violet was under investigation-light of a wave length which for practical purposes is incajlable of passing through ordinary glass. It is obvious that fur light to do any damage t.o a suhstance inside a container it must first be able to pass tliniugh the walls of the contaiiier. If the container is opaqur to ultra-violet light, then such light cannot cause decomposition of t.he materials within. The present investigation is coticerned, therefore, with the action of visible light and perhaps that in the infra-red portion of the spectrnm. Tlre foregoing effects of light would be confined largely to color and flavor of the bottled goods. In the case of natural fruit jnices, even though they may be filtered to a high degree of brilliancy and absolute sterility by means of the Sritz filter, certain finely divided colloidal substances remain in suspension in the juice. These substances, which in tlie dark will remain dispersed in the flnid apparently for years, may in certain juices become coagulated by light and result in unsightly sediments. IlonTever, only juices that are subject to this type of change are ttiose containing fluorescent substances. This effect has nut been encountered in the ahsencc of fluorescent compounds, and its method of operation is still obscure.
containers, u+th tlie possible exccpi,ion of certain juices (kraut, tomato) that may be kept in tin containers with more or less success. Glass is alinost the oiily container possible for certain juices that corrode metals. Glass containers are also iniportant iii t.hat they afford a better display uf the goods to the customer, a.nd there is little (lonbt but that the consumer prefers to see what he is buying. The transparency of glass to light brings up now prohlenis in the deterioration of products packed in glass which are not encountered with opaque containers such as t,in.
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Uir the whole the iofluence of light on tlie deterioration of jwkaged goods has received little attention. This has heen d u e to the fact that the retailer’s stock is usually supplied to hiin in corrugated hoard containers which largely exclude light nntil opened aiid placed on t h e retailer’s shelves. I < h n timi the displayed goods arc seldom placed in strung sunlight so that the usual rnetbod of retail haridliiig obviates to sonic degree the dcteiiorat.ion of light-sensitiw rnerchandise. Serger and Clarck ( I O ) called attention tu tlie fact that light and heat have an effect on the conl;titnentu giving flavor and aroma t o beverages. These writers state that red-brown glass is best for consewing glass-jiackaged products as it reduces tiie deleterious effects of light to ti niii~inium. Coe and 1,eClerc (i have ) sliown that tiie (levelopnient of rancidity of fats in various foods is mnch sluwgr in green light of a wave length of approximately 5461 A. These workers pointed out that jiotato chips wrapped in a green container were still edible after one month wliereas otherwise they were rancid within two vecks. I’rcliininary work by S‘bibataand Goda (11) has slinwri that red light and infra-red rays were mure effective tlian other light in tlie oxidation of catechol. Keeser (6) lias s h a m that invulin was rriade more active by green or blue light, but that its activity was partly destroyed by red light. Adrenaline, ini the other hand, was activated by red and green light and inhibited by blue. I d w i g and Ries (8) recorded that vitaniin 11 may he inactivated by red light and reactivated by ultra-violet. Bernoulli and Cantieni ( 1 ) have found that glucose and fructose exposed to ultra-violet light deconiposc nionoxide, ca.rbon dioxide, hyinto v ~ r i o u sgases-arbon ilrogen, and traces of oxygen. Leighton and Blacet (7) have siiown that propionaldehyde suffers decomposition and polymerization in ultra-violet light. Pierce and Morey (9) Imve found that ultra-violet light decomposes acetic acid into cartion dioxidt!, methane, and sinall arriwnts of carbon inonoxide aiid unsaturatrd hydrocarbons.
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FIGURE 2. LIGHT TRANSMISSION CURVESOF C O ~ N N G GLASSFILTERS
13outaric and Bonchard ( 2 ) found in the case of colloidal arsenious sulfide sols containing fluorescent compounds that visible and ultra-violet light hastened the rate of flocculation of arsenious sulfide veiy riiaterially, the greater cffect occurring in the ultra-violet. Tlre present writers have found an analogous &&on with respect tu kraut juice which COIItains fluorescent materials.
PREPARATION OF Jurcsri The apple jnice used in these experiments way obtainr:d from l
