40%
20% Fish Fruit Ice cream Meat Beef Lamb and mutton Pork Poultry Shel16sh Sherbet Yegetable8 Egg5
1937 1937 1934
1938 1941 1987
1,000,000 gal. 30.000 gal.
800,000,000 Ib.
I ~ , ~ Z ~ . O ~O bO . 202 307 701 I h , ~&X:OOO gai.
1937 1837
193f
1937 193‘2
1837 1941
In conjunction with these p i o d ~ , ~ i .fignleb, t ~ ~ ~ i Food 1 n d u ~ tries lists twelve different t y p c ~of dill:: methods nov in shed to the limit i s a use. What the industry could do point of conjecture, lsut n ith full ratalazatroaL of ,storage8 and somc equipment convriaions, the niiiou~>t~ could be mbstarrtially increased. A t present the 1Jmitrd States i”iuarly 15 buying ties of frozen boneless beof. A ton of b e d car^ 100 cubic feet. After lxming and p a c h n g iritn c freezing, it Q C C U ~ Eonly ~ 35 cvibrc feet. Owing to the resultstnr conservation of shipping space and tb-eight and to t h rapid ~ increase in the a i w of our a ~ m y ,i t i s piobabie that much larger amounts of beef and other meats mill be boned, packaged, and frozen for army use in the near future. Due to the shortage of tin and the necessity for other me~tm of supplementing the food supply, methods of food preservation other than canning will become increasingly important,
January, 1943
INDUSTRIAL AND ENGINEERING CHEMISTRY
27
2
INDUSTRIAL AN
The main interlocking steps t o be considered are selection of raw products, preparation for processing, actinal processing, proper packaging, correct storage, and evalunt'icm of finished product. A mistake or carel.essnessin any individual step will result in an inferior product,. The apple juice c a h n g industry has only recently recr~perat~ed. from the eEects of packing poor-quality prod,ucts. With the use of high-quality apples and better methods of preserving, such as flash pasteurization, the industry is rapidly recovering. The control of the raw product involves Raw PEQDUCT. i-nicro- and b6aMXY3SCopiC aXaKLinati62E for k l S @ C k ai?d insects injury. In addition, the ran' foodstuff must 1x2 inspected enerai a ~ ~ ~ esaid, a r in~ the ~ ~case c of ~ wrch products as peas, corn, and. lima beans, for rnaturi-i,y. A t this point the chemist is faced with B problem which has not yet been &isfactorily solved. The Tenderometer has Pound a definite place in the evaluation of raw peas in that it i s recognized generally that raw mas with a maximum value cannot be frozen and meet the nment speci5cations of fancy grade. is a maximum value, the condition However, although often arises where peas on the threshold may or may not separate to give the desired product. Corn for freezing or canning is ordinarily evaluated essentially by either a thumbnail test or by tb total solids determination of some kind. Neither of these tests has proved infallible due to several conditions. Jenkins and Lee (6) suggested t,he Tenderometer for the evaluation of raw asparagus. However, the fact must be faced that fundamentally there is no basic information on what particular constituents might be measured t o give a relatively rapid and accurate index of the ra,w product maturity. PACKAQXNG. The importance of gasti containers for the prevention of deterioration through dehydration, contamination, and oxidation is well recognized by the industry. Under present conditions frozen food ma,nufscturers are more fortunate than other food preservers in that there seems to be sufficient supp%yof moisture- and vaporproof types of cellophane papers. It i s unfortunate that the shortage of rubber has curtailed the availability of rubber composition papers and latex bags, especially since these bags were rapidly coming into use in poultry and in some kinds of fruit freezing. Work along the Knes done by DuBois and Tressler ( I ) OR proper papers for freezing can serve as an index to the best wrapping materiala to be used. The two fundamentals of proper packaging might be said to be a good paper and an effective sea.[. STORAGE.Experience has shown that most fruits and vegetables can be held satisfactorily a&5' F., altJhough 0" F. is preferable. DuBois, Tressler, and Fenton (8) indicate the importance of low-temperature storage for maintaining the original quality of meat. They demonstrated that meat held a t 0" F. maintained its fresh flavor for about a year, while meat held a t 10" and 15" F.did not stag fresh for more than 6 months. It is an interesting digression to note that when frozen beef is to be used in the type C army ration, the meat cannot have been stored for mora than 180 days. The army specifications for holding beef recommend 0" F.or lower but allow for a maximum temperature of PO" F.for short periods. In a study of holding temperatures for frozen poultry, DUB& el al. (3) showed that a t 10" F.the maximum safe holding time is about 4 months; at 0" F. it is about 6 to 12 months, depending on the package and method of preparing the bird. A t -8" F. the undrawn, properly wrapped chickens retain normal flavor after storage for 20 months. Jenkins, Tressler, et al. (6) demonstrated that, in frozen vegetables studied by them, none showed any vitamin C loss after storage at -40" F.and little or no loss at 0" F. Storage temperatures of 10" and 15' F. caused serious losses in relatively short times.
Val. 35, No. ;
Most frozen products still have a potential cnzyrnic system which can act a t ordinary storage tmiperutures. Joslyn ('7) attribut,ed flavor and other losses in some of the 'vegetables, which do not keep so well as they might in frmen storage, to the presence of peroxidaselike enzymes which are not completely inactivated by the usual blanching practices. The rsncidity of fats in cold storage poses a problem for the chemist in that work i s needed 4111 tests for incipienb rancidity. EVALUATION OF gi'r~asrrm PRODUCT. The Apicultural Marketing Service of the United States Depa,rtment of Agriculture has been setting up standa,rds and i~.fcndsto e ~ large the work or? the formulation of grades and stundsrds for frozen products. At this writing they have issued either tentative or final standards on corn, asparagus, peas, lima, beans, and frozen cherries, and have carried out experimental S , beans; work on broccoli, spinach, Brussels S ~ ~ O U ~snap cauliflower! strawberries, raspberries, m d d i c e d peaches (10). These tests in most cases are more OF less bas principal factors: coLor, avos, physical defects! and maturity. Good varieties properly handled will take care of color, flavor, and physical defects. Maturity, as in the case of peas, is ined by a sinker test, which i s essentially %B specific determination, Wkth corn tb.ere i s a t-linkeitype tes residual sugar test; this will und.oubtedly provide not only an index of maturity but also the conditions under which the corn was held prior to freezing. Lee (8) and Lee, DeFelice, and Jenkins (8) used a specific gravity test based on the principle of Archimedes. With a little refinement in technique, this type of test may find a place in the routine quality control of fronee products.
The future The importance of for upon this factor and upon consumer a the future of the froasn food industry. A s long as we are iblvo%vedin total war, every pound of perishable food which can be frozen and utilized in thk coun-. try means that more tinned goods can be made available for our soldiers and allies ins distant lands. The frozen f ~ in-~ d duatry, therefore, has, the pote~~tial task of helping to institutions, hospitals, and army camps as well as the era1 public. The ~ a ~ n t of~ morale ~ ~ ~through c e pr nutrition bas been etremed over and over. Proper nutrition means an available supply of food properly handled rend preserved t o retain the maximum nutritive value. The frozen food industry will. continue to aid in the war eRort by preserving large quantities of high-quality food, both. From the standpoint of prllatnbiiity and ilueritive valise. i$eva&ure cited (I) .DuBois, C . W., and Tresslor, D~ M., P n p e ~1'rcr.de J . , 109, No 20, K J r 16,1.8 (1938). ( 2 ) DuBois, G. W., Treasler, D. K , and Fenton, F., Proe. I n s t . Food Tech., 1, 16'6 (1940). (a) DuRois, 6. W., Tressler, 11. R.,and Fenton, P,,Eej?iu~ E n o ~ , 44,93 (1.942). (4) Frozen Foods D i h c t o r y , Food Industries. 14,N o . 6, 51 (1942). (6) Jenkins, E.R., and Le@,F.A . , Food Research, 5 , 161 (19.10). (6) Jenkins, R . E., Tressier, 2). K.*Moyev, J., and McIntosh, . I . R e f r i g . E'nu., 39, 381 (1940) (7) Joslyn, M.A . , xrid Bodford, C. Id.?IND. ENG.CIIEX.,32, 702 (1940). ( 8 ) Lee, F, A,, IND, ENG.Canba., Axha,. Em9 13, 38 (1941). (9) Lee, F. A., DeFeiice, Domenic, and Jenkins, R. It., b b i d . , 14,240 (1942) (10) Williams, F. M., Western Canner and Packer, 34, SO.8 , 6 3 (1942). APPBOVYIDb y t h e D i r e c t o r , S e w Yorli Stsate Agricultural E x p e r i m e u t Sta
tion. for publicatinn as .lourrial I'aper 5 2 3 .
