- 7 - 



an irreversi'ble dehydration of colloidal ?;els. leakage and collaDse 

 tests have been developed as a means of estimating tissue damage re- 

 sulting from the freezing process, ^or fruit pulps, to "be eaten as 

 frozen confections or desserts, r-apid freezing is important in order 

 to secure smooth texture and avoid graininoss. Commercial operators 

 must consider freezing rates in reference to product?^ "being packed. 



Storage temperatures below 10° .?. are necessary to maintain 

 the quality of most products. Above that tem-oorature enzyme action 

 may cause fairly rapid deterioration. The effect of tem-oerature 

 variations in causing ic_": cryst?il p-rowth is alf^o accentuated when 

 unfrozen syrups pro -orosont pt the higher tomooratures. Orange juice, 

 English -ocas, lima and string beans and broccoli frozen in our labora- 

 tory have been found in satisfactory condition pfter twelve months of 

 commercial storage in sealed cans at 10*^ ?, Sweet corn held under 

 similar conditions showed evidence of deterioration, but some varie- 

 ties were still acceptable. 



A number of materials are used for loackaging frozen fr^jits and 

 vegetables. Tin plate and glass containers, -oarticularly when vacuum 

 sealed, afford the greatest degree of protection against evaporation, 

 oxidation and absorption of forei.^rn odors. Sealed containers are in- 

 dispensable for frozen orange juice to be stored for any length of 

 time. Unfortunately, buyers have become used to sterilized food pro- 

 ducts in sealed containers, and expect frozen products to keep in- 

 definitely until the seal is broken, regardless of the temperature. 



Transparent latex rubber films and lacciuered cellophane 

 afford the next greatest degree of protection against drying and 

 absorption of odors from storago room atmos\-;here. Paper coated 

 with paraffin is more porous at low temperatures, and orange jp.ice 

 stored in waxed paper cups shows excessive cv-noration and oxida- 

 tion after five months storage. 



Combination packages consisting of lacauered cellophane bags 

 in waxed -naper cartons wrapped with waxed glassine are commonly used 

 for ■oacka-'^es containing less than five pounds of frozen vegetables. 

 Heavy v^axod cardboard tubs and slip top cans are freouentl^'' used as 

 containers for five and ten poiinds of vegetables. Cans and barrels 

 are used for storing larger amoii^nts. Ccr^ainer manufacturers are 

 experimenting with new containers for frozen foods. 



VARIETAL ALAFTA3ILITX 1.2 SOUTH TEXA S; 



Citrgp Juice; In tests made during two seasons, Yalencia orange juice 

 which had been reamed, screened, deaerated and sealed in air tight con- 

 tainers showed excellent quality after one year in commercial storage 

 at lO"^ E. Pineapple, Hamlin and Parson Brown orange juices arc satis- 

 factory, and l^lavel orrnge juice is fairly sat isf-^ct ory in tests made 

 to date. Erozen grapefruit juice and sections show no outstanding 

 advantage over properly canned products of the same fruit. 



