Preparation of Standard Reference Material 2383 (Baby Food Composite) and use of an interlaboratory comparison exercise for value assignment of its nutrient concentrations.

The preparation of the recently released Standard Reference Material (SRM) 2383 Baby Food Composite and the process used for value assignment of nutrient concentrations are reported. SRM 2383 can be used as a control material when assigning values to in-house control materials and when validating analytical methods for measuring proximates, vitamins, and minerals in baby food and similar matrixes. The SRM was prepared as a commercial baby food would be prepared, with the same ingredients. The Certificate of Analysis for SRM 2383 provides assigned values for concentrations of proximates, vitamins, and minerals for which product labeling is required by the Nutrition Labeling and Education Act of 1990. These assigned values were based on measurements by the National Institute of Standards and Technology (NIST) and/or collaborating laboratories. Assignment of analyte concentrations based solely on analyses by collaborating laboratories is described in this paper. Certified values are provided for retinol, tocopherols, and several carotenoids including total beta-carotene; the certification of and methodology used for measurement of these analytes is discussed in a companion paper (this issue, page 288). Reference values are provided for solids, ash, fat, nitrogen, protein, carbohydrate, calories, vitamin B1, vitamin B2, vitamin B6, niacin, biotin, calcium, phosphorus, magnesium, manganese, iron, zinc, copper, sodium, potassium, and chloride. Reference values for additional carotenoids are reported in the companion paper (this issue, page 288). Information values are provided for iodine, selenium, molybdenum, vitamin D, vitamin B12, folic acid, pantothenic acid, choline, inositol, sugars, total dietary fiber, and 3 classes of fats.

Monitoring behavioral changes in diabetes care with the diabetes self-management record.

An evaluation instrument called the diabetes self-management record has been developed to better document the positive behavioral changes associated with diabetes education programming. This record is a simple behavior monitoring system that awards points for positive behaviors associated with exercise, glucose monitoring, and nutrition management. A group of 39 adults with diabetes monitored their behaviors with the record prior to, immediately after, and 4 to 6 weeks following a diabetes education programming course. Overall diabetes management scores were higher (mean +/- SEM = 56.2 +/- 3.5 vs 66.3 +/- 2.9) following the educational intervention, as well as specific behavioral scores for exercise, glucose monitoring, fat consumption, refined sugar/carbohydrate consumption, and eating behavior. These behaviors were maintained for at least 4 to 6 weeks postprogramming. The diabetes self-management record can be used as an adjunct to diabetes education programming, as an evaluator of the educational intervention, and/or as a behavior monitoring tool for diabetes self-management.

Detection of adulteration in apple juice by L-malic/total malic acid ratio: collaborative study.

L-Malic acid is the predominate acid in pure apple juice and no D-malic acid should be present. Synthetic malic acid contains 50% D-malic acid, is inexpensive, and can be used to create nonauthentic apple juice. L-Malic/total malic ratios of 0.9 or less are indicative of a nonauthentic sample. Fourteen laboratories participated in a collaborative study to determine the L-malic/total malic acid ratio in apple juice. Ten samples of apple juice were sent to each laboratory. Authenticity of the samples varied from 0 to 100%. The coefficients of variation in all cases were acceptable, i.e., ca 5%. The method was adopted first action by AOAC INTERNATIONAL.

Optimized Monier-Williams method for determination of sulfites in foods: collaborative study.

A collaborative study was conducted of the Food and Drug Administration (FDA)-optimized Monier-Williams method for determining sulfites in foods. Twenty-one industry and government laboratories participated in the study, which was jointly sponsored by the National Food Processors Association and FDA. Familiarization samples were shipped to each collaborator. Collaborators were permitted to proceed to the main study only after they demonstrated ability to perform the method to ensure that the study tested the performance of the method itself and not that of the individual laboratories. The study design involved 3 food matrixes (hominy, fruit juice, and protein [seafood]). Each matrix was prepared at 3 sulfite levels--the regulatory level, half the regulatory level, twice the regulatory level--and as a blank. All test samples were analyzed as blind duplicates, which gave each collaborator a total of 24 test portions. Collaborative recoveries gave a reproducibility (among-laboratories) coefficient of variation that ranged from 15.5 to 26.6% for sulfite determined as SO2 by weight in the 3 foods at the 10 ppm level. The optimized Monier-Williams method has been approved interim official first action to replace the AOAC modified Monier-Williams method, 20.123-20.125.

Effect of commercial processing on pesticide residues in selected fruits and vegetables.

Commercial food processing operations such as washing, blanching, and cooking remove major portions of the pesticide residues that are currently permitted on the raw agricultural crop. These unit operations are reviewed for selected products, along with degree of residue removal at each step. For example, washing plus peeling removes 99% of carbaryl and malathion residues from tomatoes. Washing removes 83% of benomyl residue from tomatoes and further processing reduces the residue by 98% in tomato puree and catsup. Even in the most concentrated fraction from tomatoes (tomato paste), residues were below the initial level in the raw product.

Metabolic, thermoregulatory, and psychophysiological responses during arm and leg exercise.

The present investigation compares metabolic, thermoregulatory, and psychophysiological responses during upper and lower body exercise in different environmental conditions. Eight males performed four, 60-min exercise bouts using either arm or leg ergometry in ambient temperatures of 23 degrees C (relative humidity = 75%) and 33 degrees C (relative humidity = 57%). Power output was 75 W for all experiments. Oxygen consumption, rectal and skin temperatures, heart rate (HR), and rating of perceived exertion were measured during exercise. Exercise oxygen consumption averaged 1.54 l.min-1 across all experiments and was equivalent to 60% of arm and 37% of leg peak values. Rectal temperature increased (P less than 0.001) an average of 0.43 degrees C and did not differ due to experimental conditions. Exercise performed in the heat resulted in higher skin temperature (P less than 0.001), regardless of whether the arms or legs were used. HR and rating of perceived exertion were greater (P less than 0.001) in arm (132.9 b.min-1, 14.4 units) than leg (108.9 b.min-1, 10.9 units) experiments. When arm exercise was performed in the heat, HR was 6 b.min-1 greater than when performed in the cool. Greater relative exercise intensity in arm work resulted in higher HR and rating of perceived exertion at the given power output. Similar rectal temperature increases in all experiments indicate that core temperature is controlled by absolute heat production, regardless of mode of exercise and ambient temperature.

Hearing loss in the elderly: an epidemiologic study of the Framingham Heart Study Cohort.

This study used epidemiologic methods to examine hearing loss in the elderly. The Framingham Heart Study Cohort was the reference population. The participants were 935 men and 1358 women, aged 57 to 89 years. Using a conservative definition of hearing loss as threshold levels greater than 20 dB above audiometric zero for at least one frequency from 0.5 to 4 kHz, the prevalence was estimated to be 83%. The majority of cases displayed a sensorineural hearing loss. There were no statistically significant differences by sex at 1 kHz and below. Women had significantly better hearing than men at 2 kHz and above. A multivariate model was constructed to determine which variables had a significant impact upon hearing loss. Under the model, age, sex, illness, family history of hearing loss, Meniere's disease, and noise exposure were significant population risk factors. Age was by far the most critical risk factor.

Analytical methods used by industry for determining lead in processed foods.

Over the past 8 years, a number of food processors and can manufacturers have participated in repeated round-robin studies of lead methodology. During this period, 3 methods have been found to be comparable in a variety of foods: carbon rod atomic absorption, chelation-solvent extraction atomic absorption, and anodic stripping voltammetry. Each method is described and results are given from a number of round-robin studies. In general, the coefficient of variation at lead levels of 0.1-0.3 ppm is usually less than or equal to 20%.

Atomic absorption determination of tin in foods: collaborative study.

Samples of green beans, applesauce, and a fruit juice were fortified with tin at 3 levels. Collaborators were asked to digest the samples, using HNO3-H2SO4, add methanol to enhance the absorption signal, and aspirate directly, using a nitrous oxide-acetylene flame. Results were received from 8 laboratories including 4 from Europe. However, only 6 laboratories used the prescribed methodology. All results were considered acceptable. The method has been adopted as interim official first action.

Leak in evaporated milk by anodic stripping voltammetry and atomic absorption spectrophotometry: cooperative interlaboratory study.

The results of a cooperative study on the determination of lead in evaporated milk, using a double blind referee technique, are reported. This study was designed to determine the normal variability of methods currently used for lead analysis by canned food industry laboratories. Twenty-three laboratories participated in this study. Each laboratory was instructed to use atomic absorption spectrophotometry (AOAC 25.065), anodic stripping voltammetry, or carbon rod atomic absorption spectrophotometry. Overall, the results appear to be in close agreement with the spiking levels. The coefficient of variation for all laboratories was 36.0% at the 0.15 ppm lead level and 16.8% at the 0.40 ppm lead level.

A simplified method for the gas-liquid chromatographic determination of methyl mercury in fish and shellfish.

A simple acetone wash of the fish sample which removes lipids and other organic materials replaces the cystein cleanup specified in other methods. Methyl mercury is freed by hydrochloric acid, extracted into benzene, and determined with a gas-liquid chromatograph equipped with an electron capture detector. The method is quantitative for methyl mercury levels as low as 0.10 ppm in fish and shellfish. Ethyl mercury chloride may be used as an internal standard to detect unsuspected error or instrumental parameter variation.