48 MASS. EXPERIMENT STATION BULLETIN 441 



a decided effect on the required process times. Allowances should be made In 

 prescribed process times to cover these variations. 



Glass-Packed Citrus Juices. (W. B. Esselen, Jr., J. E. W. McConnell, and 

 C. R. Fellers.) Further storage tests at 35°, 50°-60°, and 70°-85° F. (room 

 temperature), on commercially packed grapefruit juice, orange juice, and a blend 

 of grapefruit and orange juice, In cans and In glass containers, substantiated 

 previous observations that the ascorbic acid content Is well retained alter storage 

 for one year. Juices stored at 35° and at 50°-60° for one year showed no significant 

 change in color and flavor, while samples stored at room temperature (70°-80°) 

 retained their original quality for six months but after that showed a marked 

 deterioration In flavor. At room temperature the color of the glass-packed 

 orange juice stood up quite well, but the grapefruit juice and the grapefruit- 

 orange juice blend packed In glass containers darkened considerably after six 

 months. From the experimental results It appears that it should be possible 

 to place good-quality glass-packed citrus juices on the market If warehouse 

 temperatures are maintained at 50°-6O° F. or lower. Cold storage at temperatures 

 of 35°-40° F. is not necessary. 



Prevention of Darkening and Deterioration in Flavor of Citrus Juices. (J. E. 



W. McConnell, W. B. Esselen, Jr., C. MacCormack, A. Kaplan, and C. R. 

 Fellers.) The addition of ascorbic acid or the storage In an inverted position of 

 bottles sealed with plain tin coated caps favored color retention In citrus juices. 

 The combination of both factors produced more favorable results than either 

 alone. 



Added tin In the form of stannous Ions had a stabilizing effect on the color of 

 bottled orange juice. The optimum concentration of stannous Ions, as deter- 

 mined by accelerated storage tests, was between ICO and 200 p. p.m. Small 

 amounts of iron (above 8 p. p.m.) accelerated darkening of the juice. 



The value of various substances as antioxidants for orange juice was investi- 

 gated by ailding them to the juice at 0.1 percent concentration and submitting 

 the bottled, pasteurized juice to an accelerated storage test at 125° F. Among 

 the substances tested were p hydroxydlphenyl, p aminoacetophenone, i-h^'droxy 

 quinoline, orclnol, catechol, caffeic acid, ghdne, ethyl and propyl gallate, and a 

 series of quinones having oxidation-reduction potentials between -{-0.131 and 

 -1-0.656 volts. The gallates and sodium 2.7 anthraquinonedlsulfonate (oxida- 

 tion-reduction potential -|-0.242) were the onh' substances tested which protected 

 the orange juice against flavor deterioration; however, they had little or no 

 effect on the color. 



Color Measurement of Citrus Juices by Means of a Photoelectric Reflection 

 Meter. (W. B. Esselen, Jr., M. Paparella, J. E. W. McConnell, and C. R. Fellers.) 

 Determination of the amount of light reflected by citrus juices by means of a 

 photoelectric reflection meter was found to provide a rapid and accurate Index 

 of the color of the juices and a good method for following color changes in the 

 juices during storage. Correlation with visual grading was as good as or better 

 than the correlation between visual grading and light transmission values de- 

 termined on the filtered juices. This method of color determination should be 

 especially useful in following surface discoloration. 



A white reference standard may be used, but maximum sensitivity may be 

 obtained by using a colored reference standard similar to the color of the product 

 being examined. In following color changes of foods during storage, the band 



