Preparation procedures of food and beverage samples for oxygen bomb calorimetry: A scoping review and reporting checklist

Abstract

Standardised bomb calorimetry methods are essential to accurately quantify the gross energy within food and beverages, yet no accepted protocols exist. The objective of this review was to synthesise literature on food and beverage sample preparation methods used for conducting bomb calorimetry. This synthesis enhances our understanding of the extent to which methodological variances may currently affect estimates of the caloric values of dietary items. Five electronic databases were searched for peer reviewed literature on food and beverage energy measurement via bomb calorimetry. Data were extracted on seven identified methodological themes, including: (1) initial homogenisation, (2) sample dehydration, (3) post-dehydration homogenisation, (4) sample presentation, (5) sample weight, (6) sample frequency, and (7) equipment calibration. A tabular and narrative approach was used to synthesise the data. Studies that specifically explored the impact of any methodological variance on the energy derived from foods and/or beverages were also considered. In total, 71 documents describing food and beverage sample preparation techniques and processes used for bomb calorimetry were identified. Only 8% of studies described all seven identified sample preparation and calibration processes. The most frequent approaches used included: initial homogenisation – mixing or blending (n = 21); sample dehydration – freeze drying (n = 37); post-dehydration homogenisation – grinding (n = 24); sample presentation – pelletisation (n = 29); sample weight – 1g (n = 14); sample frequency – duplicate (n = 17); and equipment calibration – benzoic acid (n = 30). The majority of studies that have measured food and beverage energy via bomb calorimetry do not describe sample preparation and calibration methods in detail. The extent to which different sample preparation processes influence the energy derived from food and beverage items is yet to be fully elucidated. Use of a bomb calorimetry reporting checklist (described within) may assist with improving the methodological quality of bomb calorimetry studies.