Beverage sample preparation and procedures for bomb calorimetry: Establishing equivalency in methods

Standardised bomb calorimetry methods (sample preparation and combustion techniques) are essential to accurately quantify the caloric value of food and beverages, yet no protocols exist. This study evaluated the influence of various methodological approaches to establish those most reliable for beverage calorie determination. Equivalence testing was used to verify if differences between means (and 90% CI) were within established margins. Standardised test beverages included a low- and high-fat version. Part A determined a coefficient of variation for establishment of equivalence margins; Part B assessed differences between calorimetry methods. Elements evaluated included: initial sample homogenisation, sample dehydration, post-dehydration homogenisation, sample presentation, sample weight, combustion pressure, and sample storage. Aspects that may be critical to reliably determine the gross energy content of beverages include initial agitation, dehydration level (%), post-dehydration homogenisation, pre-combustion sample presentation and sample storage time. Ovendried high-fat samples had the largest deviations from equivalence, particularly those not agitated prior to dehydration or combustion, or not dehydrated to a constant weight. Some methods do not exhibit differences, such as low-fat sample pre- and post-dehydration homogenisation, dehydration method and temperature, sample weight, and combustion pressure. These findings identify critical aspects of sample preparation and combustion for the caloric determination of beverages.