Microbiological Assay-Trienzyme Procedure for Total Folates in Cereals and Cereal Foods: Collaborative Study

In 1996, U.S. Food and Drug Administration regulations mandated the fortification of enriched cereal-grain products with folic acid, thereby emphasizing the need for validated methods for total folates in foods, particularly cereal products. The AOAC Official Methods (944.12, 960.46) currently used for the analysis of folate in foods for compliance purposes are microbiological methods. When the fortification regulations were finalized, no Official AOAC or Approved AACC methods for folate in cereal-grain products were in place. The AOAC Official Method (992.05) for folic acid in infant formula does not incorporate important improvements in the extraction procedure and was not considered suitable for the analysis of folates in foods in general. Amicrobiological assay protocol using a trienzyme extraction procedure was prepared and submitted for comments to 40 laboratories with recognized experience in folate analysis. On the basis of comments, the method was revised to have the conjugase (gamma-glutamyl-carboxy-peptidase) treatment follow a protease treatment, to include the use of cryoprotected inoculum, and to include the spectroscopic standardization of the standard and optional use of microtiter plates. Thirteen laboratories participated in a collaborative study of 10 required and 10 optional cereal-grain products, including flour, bread, cookies, baking mixes, and ready-to-eat breakfast cereals. The majority of the participating laboratories performed the assay by the standard test tube method; others used the microtiter plate modification for endpoint quantitation with equal success. For the required products, the relative standard deviation between laboratories (RSDR) ranged from 7.4 to 21.6% for 8 fortified (or enriched) products compared with expected (Horwitz equation-based) values of 11–20%. RSDR values were higher (22.7–52.9%) for 2 unfortified cereal-grain products. For the optional products, the RSDR ranged from 1.8 to 11.2% for 8 fortified products. RSDR values were higher (27.9–28.7%) for 2 unfortified cereal-grain products. Based on the results of the collaborative study, the microbiological assay with trienzyme extraction is recommended for adoption as Official First Action.

Microbiological assay-trienzyme procedure for total folates in cereals and cereal foods: collaborative study

In 1996, U.S. Food and Drug Administration regulations mandated the fortification of enriched cereal-grain products with folic acid, thereby emphasizing the need for validated methods for total folates in foods, particularly cereal products. The AOAC Official Methods (944.12, 960.46) currently used for the analysis of folate in foods for compliance purposes are microbiological methods. When the fortification regulations were finalized, no Official AOAC or Approved AACC methods for folate in cereal-grain products were in place. The AOAC Official Method (992.05) for folic acid in infant formula does not incorporate important improvements in the extraction procedure and was not considered suitable for the analysis of folates in foods in general. A microbiological assay protocol using a trienzyme extraction procedure was prepared and submitted for comments to 40 laboratories with recognized experience in folate analysis. On the basis of comments, the method was revised to have the conjugase (gamma-glutamyl-carboxy-peptidase) treatment follow a protease treatment, to include the use of cryoprotected inoculum, and to include the spectroscopic standardization of the standard and optional use of microtiter plates. Thirteen laboratories participated in a collaborative study of 10 required and 10 optional cereal-grain products, including flour, bread, cookies, baking mixes, and ready-to-eat breakfast cereals. The majority of the participating laboratories performed the assay by the standard test tube method; others used the microtiter plate modification for endpoint quantitation with equal success. For the required products, the relative standard deviation between laboratories (RSD(R)) ranged from 7.4 to 21.6% for 8 fortified (or enriched) products compared with expected (Horwitz equation-based) values of 11-20%. RSD(R) values were higher (22.7-52.9%) for 2 unfortified cereal-grain products. For the optional products, the RSD(R) ranged from 1.8 to 11.2% for 8 fortified products. RSD(R) values were higher (27.9-28.7%) for 2 unfortified cereal-grain products. Based on the results of the collaborative study, the microbiological assay with trienzyme extraction is recommended for adoption as Official First Action.

Jaundice and rash associated with the use of phenobarbital and hydrochlorothiazide

Rash, lymphadenopaty, splenomegaly, periorbital edema, and hepatitis occurred in an 18-year-old woman who was taking phenobarbital and hydrochlorothiazide. Tests for fluorescent antinuclear antibody and hepatitis-associated antigen and antibody were negative. Liver biopsy was not characteristic of viral hepatitis. Clinical recovery occurred within two weeks. Treatment consisted of withdrawal of the above drugs plus the administration of methylprednisolone and diphenhydramine.

New thoughts concerning xanthogranulomatous pyelonephritis (X-P)

A clinical and roentgenographic analysis of 13 patients with pathologically proved xanthogranulomatous pyelonephritis (X-P) has demonstrated that many previously accepted truisms associated with this disease may not be valid. As a result of this study it is suggested that X-P: 1. Does have a prominant female distribution. 2. May arise relatively acutely. 3. Can be associated with a well-functioning kidney. 4. May destroy the kidney and collecting system. 5. Does not demonstrate neovascularity. 6. Can be distinguished angiographically from hypernephroma. 7. May be associated with diabetes. Other important facts were again observed: 1. X-P is still often associated with staghorn calculi and urinary tract obstruction. 2. Proteus mirabilis is the main offending organism.