A Precollaborative Study of Weight Determination Methods for Quick Frozen Shrimp

Abstract

A precollaborative study compared the accuracy and precision of official AOAC methods with other selected methods for determining net weight of IQF-glazed shrimp and block-glazed shrimp, assessed the ruggedness of the methods with respect to changes in the levels of the factors under study, and selected candidate methods for use in a collaborative study. Methods tested for determining deglazed (frozen) net weight of IQF-glazed shrimp were (1) AOAC Method 963.18 and (2) the Water Bath Dip Method. Methods tested for determining thawed net weight of IQF-glazed shrimp were (1) AOAC Method 967.13, (2) Modified AOAC Method(mnb) 967.13, (3) Modified AOAC Method(pb) 967.13, (4) the Codex Method, (5) the Air Thaw Method, and (6) Modified AOAC Method 963.18. The same methods except Modified AOAC Method 963.18 were tested for determining thawed net weight of block-glazed shrimp. A total of 864 0.45 kg (1 lb), 0.90 kg (2 lb), and 1.35 kg (3 lb) IQF-glazed shrimp test samples and 234 2.25 kg (5 lb) block-glazed shrimp test samples were collected. During sample preparation, test samples were subjected to either water with or without sodium tripolyphosphate (STP). During deglazing (IQF-glazed shrimp only) and/or thawing, test samples were allocated in a factorial design to assess the effects of STP presence (no STP and STP), sieve mesh sizes (2.83 and 2.38 mm; 0.11 and 0.09 in.), and sieve diameters (20 and 30 cm; 8 and 12 in.). During weighing, test samples were further allocated to a sequence of weighing procedures designed to assess the effects of using sieve weights (dry and wet) in combination with paper towel use (no and yes) and tared pan weights when calculating determined net weights. On the basis of the results of this precollaborative study, Modified AOAC Method(pb) 967.13 and the Air Thaw Method seem to be the best methods to determine net weight of IQF-glazed and block-glazed shrimp. Therefore, to validate method choices in the collaborative study, the authors recommend analysis of IQF-glazed shrimp and block-glazed shrimp test samples, each prepared with or without STP, by Modified AOAC Method(pb) 967.13 and the Air Thaw Method. To fulfill AOAC requirements, IQF-glazed shrimp and block-glazed shrimp test samples, each prepared with or without STP, must be analyzed by official methods: AOAC Method 963.18 (IQF-glazed shrimp only) and AOAC Method 967.13. During testing, sieve mesh size will be either 2.83 or 2.38 mm (0.11 or 0.09 in.), sieve diameter will be limited to 30 cm (12 in.), and weighing procedure will be limited to tared pan.