Vitamin C Content of Strawberries and Strawberry Ice Cream C. R. FELLERS AND 11. J. MACK, Massachusetts State College, Amherst, Mass.
W
I T H modern refrigdied in 26 to 33 days with an Howard Supreme and Klondike rarieties of erated transportation average Sherman scurvy wore fresh strawberries are excellent sources of vitamin methods, fresh strawof 14. C, only two grams giving good weight gains berries are found in the public SAMPLES and f u l l protection f r o m s c u r y . Preservation 111a r k e t s f r o m December to of strawberries by freezing, with or without August. Strawberries have thus Two lots of fresh strawberries Iiecome increasingly important were fed: (1) mainly Klondike sugar, has no harmful effect on the citamin C from a dietary viewpoint. The variety shipped from the South, content of the fruit. Strawberries when infruit is also extensively frozen and (2) locally grown Howard corporated in ice cream show no measurable both w i t h sugar (frozen-pack) Supreme. The Klondike variety loss of vitamin C. This is attributed to the low a n d unsm-eetened. il s m a l l was available for only 50 days; temperatures at which agitation, air incorporaquantity is also canned. other mixed varieties were used Smith, Bergheim, and Hawk for the last 22 days. Similarly, tion, and storage take place. ( $ ) Dresented no data but briefly Howard Supreme w a s f e d f 01. reported that scorbutic guinea 46 days, and mixed ever-bearpigs were cured in seven days by the daily administration of ing varieties for the last 26 days of the experiment. Howard Supreme variety, frozen with sugar in the ratio 10 cc. of freshly expressed strawberry juice. Juice which had been boiled for 5 minutes was equally active in curing scurvy. of two to one and held in freezing storage a t 0" F. (-17.8" Kohman, Eddy, and Halliday ( 1 ) determined the protective C.) was fed in the first test. The berries were packed into dose of strawberries (variety unnamed) to be 2 to 3 grams. one-gallon cans. Small samples were removed from the cans Autopsy findings were not reported. They found Oregon as needed, thawed, and fed to the animals. canned strawberries to be of about the same potency. I n the second test, unsweetened Klondike strawberries, Scheunert ( 2 ) in Germany assayed several varieties of fresh frozen and stored by the Birdseye Laboratories in one-pound drawberriesand found the daily protective dose to be 5 grams waxed paper cartons, were used. These berries had been in or less. Canning and preserving slightly decreased the vita- storage from 4 to 7 months. The ice cream mix consisted of 12 per cent vitamin C-free min C potency. No data have been reported on frozen strawberries, in spite butter fat, 10 per cent baked skim milk powder, 15 per cent of the fact that this is by far the most important method of sugar, 0.30 per cent gelatin, and 63 per cent water, and i t was preservation. Frozen strawberries are now available the pasteurized a t 150" F. (65.6" C.) for 30 minutes, homogenized year round in many stores. Furthermore, huge quantities at 3000 pounds per square inch (211 kg. per sq. em.) pressure, are frozen-packed with sugar for use in the preserve, sirup, cooled to 40" F. (4.4" C.), and aged for 20 hours a t 40" F. bakerv. and ice cream industries. Earlv in 1932 a study of Thirty per cent of defrosted, frozen-packed Klondike fresh and frozen strawberries and strawstrawberries (two parts of fruit to one berry ice cream was begun to ascertain of sugar) was added to the mix at the L@O the effect of manufacturing processes beginning of the freezing process. The on the vitamin C content of the fruit. freezing process required 10 minutes, after which the ice cream was drawn 330 EXPERIMENTAL PROCEDURE from the freezer into cans a t a n overrun of 90 per cent and a temperature The Sherman, La Mer, and Campbell 200 of 23" F. (-5" C.). The ice cream method ( 3 ) was used with the exception was held a t -5°F. (-20.6OC.) until that the amounts fed were proportioned used (1 to 3 months). Ten grams of to the weight of the guinea pigs-i. e., a 100 ice cream thus contained the equivalent 400-gram animal was fed four-thirds as of 2 grams of strawberries. much as one weighing 300 grams. The 0 animals mere all young and healthy, RESULTS weighed between 280 and 325 grams, and were h o u s e d in individual cages. The results are given in Table I and -100 The basal ration consisted of 58 per cent Figure 1 and clearly show that both 30 60 90 equal parts of rolled oats and wheat fresh or frozen Howard Supreme and FIGURE1. VIT.4MIX c I N FRESHAND bran, 30 per cent of milk powder free of K l o n d i k e s t r a w b e r r i e s are richly FROZEKSTRAWBERRIES A N D STR.4Wvitamin C (baked), 10 per cent butter endowed with vitamin C. Two grams BERRY ICECREAM fat, 1 per cent each of cod liver oil and daily, the lowest quantity fed, were (1) Frozen s t r a a b e r r i e s , no added sugar, 2 salt. Water was kept before the animals fully protective from scurvy and prog r a m s ; scurvy score, 0. (2) F r e i h strawberries, 2 grams: scurvy a t all times. duced large weight gains. There was score, 0. Three guinea pigs normally were used (3) Frozen-pack strawberries with s u g a r , 2:1, apparently no loss in the freezing and 3 g r a m s , equivalent t o 2 grams of u n a t each feeding level. At the end of the sweetened f r u i t ; scurvy score, 0. storing processes either with or with(4) Strawberry ice cream containing 30 per feeding period all animals were chloroout sugar. S i m i l a r l y , when frozencent of frozen-pack strawberries ( 3 ) , 10 g r a m s equivalent t o 2 g r a m s of u n formed and carefully e x a m i n e d for packed strawberries were used in strawsweetened f r u i t . scurvy score, 0. lesions of scurvy. Segative c o n t r 01 s berry ice cream, they r e t a i n e d their ( 5 ) Negative control.' "
I
1051
INDUSTRI4L I S D ESGINEEHING CHEMISTRY
1032
T 4BLE I.
ITA AN IN
PRODUCT
.\SI\I~LS
F r e s h , Howard Supreme strawberries F r e s h Klondike strawberries Frozenstraaberries n i t h sugar; 2 parts berries t o 1 of sugar Strawberry ice cream, containing 30% frozen-pack berrier a s above Frozen strawberries; no added sugar S e g a t i v e control
c L4ss.4Y O F
3 3 3 3 2 2 2 4 4 3 3 3 2
FRESH A S D
DAILY DOS~GE Grams 2
4
2 4 3 6 9 10 15 9
3 4 0
FROZES STRAWBERRIES ASD
AT. G.us I N T~EIGHT Grams 300 28i 337
299 345 269 - 1.’ 320 222 425 285 270 -109
original antiscorbutic potency. I n spite of the beating in of air and agitation by the dasher of the freezer, the low temperature must exert a marked protective action on the vitamin C. I n this laboratory similar treatment a t higher temperatures n i t h tomatoes and cranberries has caused marked losses of vitamin C. Attention is called to the depressing effect on growth of excessively large doses of either strawberries or strawberry ice cream. This effect has been repeatedly noted in other vitamin C assays and may be due to the disturbing effect on the digestive and nervous systems and to the unbalancing of the diet. I n spite of poor or even negative weight gains, no scurvy was found on autopsy in any animal in this expeiimen t .
STRAM BERRY
.iv. S ~ R T I T A L SCURVY PERIOD S C O R E Dnus 70 0 io 0 72 0 72 0 90 0 90 0 90 0 90 0 90 0 90 0 90 0 90 0 33
13
1-01, 2 5 . No. 9
ICECRE.LX1
Berries available only 70 d a y s Berries available only i 2 days
.......... . . . One animal died a t end of 41 day:: no w u r v y One animal died a t end of 26 d a y s ; i i o scurvy One animal sick during last 2 s-eeks of period ; no scurvy Severe s c u r v
ACKNOWLEDGMENT The Klondike frozen strawberries were packed, frozeii, and stored by the Birdseye Laborat,ories, Gloucester, 1\Ia.:,s. IJITERATURE C I T E D
(11 Kohnian, E. F.,Eddy, W. H., and IIalliday, S . . ISD. ESG. HEM., 20, 202-4 (1928). ( 2 ) Scheunert, .i., ” D e r Titamingehalt der d e u t s c h e i i Xiahriings-
mittel. I. Obst und Gzmuse,” Springer, 19L’!). (3) Sherman, H. C.‘., La Mer, V. K., and Campbell. H . L., J . -1m. (‘hem. SOC., 44, 165-72 (1922). (4) Smith, C. -I., Rergheim, O., a n d Hawk, P. B.. 1’i.o~. .Sue. E r p t l . id. .\led., 19,228 (1921). RECEIVED F e b r u a r y 17, 1933. Presented before t h e Division of Agricultural and Food Chemistry a t t h e 85th Meeting of t h e American Chemical Society, K a s h i n g t o n , D. C . , March 26 t o 31, 1933.
Yeast-Growth Stimulants in White Sugars 13. 13. HALL,LAWREKCE €1. JAMES.AXD L. s. STUART B u r e a u of C h e m i s t r y and Soils, W a s h i n g t o n , D. C.
T
HE presence of stimulating substances in sugar and
other materials is highly important in fundamental studies of yeast metabolism, in commercial fermentation processes, and in many other instances in which the growth of such microorganisms is a vital factor. I n the commercial manufacture of beverages difficulty has arisen owing to the development of yeast precipitates or clouding in bottled goods during storage. This type of spoilage has frequently been attributed to sugars, and a n attempt to determine the extent and probable importance of nonsugar growth-stimulating substances has been made.
SALTSAS POSSIBLE STIMULANTS Most syithetic media selected for investigations of thib nature contain sucrose as a basic nutrient. The possibility of salts (carried in the sugars as contaminants) acting as growthpromoting substances was considered, and an attempt was made to detect their presence by using the sugars in a synthetic medium which had been deprived of one or another of its necessary ions. I n the early part of this investigation each sugar mas added to Fulmer, Selson, and Sherwood’s medium F ( 2 ) from which first one and then another of the recommended salts had been eliminated. This medium F contains ammonium chloride, calcium chloride, dipotassium phosphate, calcium carbonate (precipitated), dextrin, and sucrose. The first test was to determine whether the phosphorus was adequate. Medium F was prepared in 100-cc. quantities with and without added phos-
pliater, and the different sugars were added. (I’otaAuiii n-as provided in the form of potassium carbonate.) The media. were sterilized and inoculated with 0.1 cc. of a water suspension of yeast cells from a 24-hour wort agar slant. (The yeast used in this study mas isolated from a beverage in which a sufficient crop had developed to cause a visible sediment. This culture was well suited to this study because of its apparent demand for the particular growth-promoting substance under investigation. It has been identified as a variety of Saccharomyces cerecisiae.) From three to ten thousand yeast cells were inoculated into each flask. The cells had been centrifuged and washed repeatedly. After 48 hours of incubation, total numbers of viable organisms were determined in wort agar plates, The results are shown in Table I. TaRLE
I. I-EAST GROWTHS OBTAINEDIN WITH
S U G . ~ R WITH SAMPLE A D D E D POa 1 4,820,000 2 2,120,000 3 7,840,000
.om
WITHOUT
\$’ITHOUT ~ D D E DPOI
2,640,000 900,000 630,000
&IEDICJI
PHOSPHATES
sUG,iR
SAMPLE 4 5 6
Tt-ITH .\DDED Po1
i,OOO,OOO 476,000 544.000
F
!\-ITHOCT .\DDED POL
33,000 7,000 3,000
I t is evident that the addition of phosphates to the modified medium (i. e., inediurn F complete) increased the growth with every sugar tested. This indicated that, in general, t h e sugars were not supplying sufficient amounts of this salt, although the amount of growth in sample l indicated that t h a t particular sugar furnished sufficient phosphates for marked yeast development.
