Graduate Thesis Or Dissertation
 

Development and characterization of shelf-life and sensory properties of restructured albacore tuna (Thunnus alalunga) rolls

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  • Albacore tuna (Thunnus alalunga) rolls were developed using two albacore meat levels and three different treatment combinations. Albacore meat levels of 82 and 88% (Alb82 and Alb88) of the total weight formulation were examined. The different treatments consisted of 0.3% sodium tripolyphosphate (STPP), 0.3% STPP plus nitrites (150 ppm), and a third treatment of 0.3% STPP, plus nitrites (150 ppm) and rosemarinic acid (38 ppm), on a total formulation basis. The first study monitored possible changes in composition, oxidation, fatty acid profiles, microbial counts and texture of albacore rolls kept in vacuum-sealed packages and open packaging. Albacore rolls in vacuum-sealed packaging studies were stored at 2º C for 52 and 120 days. Compositional studies of the vacuum-sealed packages revealed that moisture and lipid content of tuna rolls developed with different meat levels were similar, but protein content was significantly higher in Alb88. Oxidation numbers of vacuum-sealed samples remained below 2 mg malonaldehyde (MDA)/kg of sample throughout testing periods, regardless of the treatment used. Fatty acid profiles remained stable throughout the study. Shelf life analysis showed that bacteria, yeasts and molds remain at very low levels as long as the packaging remained sealed during storage at 1.5ºC. In general, textural studies showed that rolls processed with 88% meat displayed less cohesiveness and springiness than those processed with 82% meat. Hardness was not significantly different between meat levels. Samples with nitrite were significantly firmer, more cohesive, and more elastic than samples without it. The open package study was carried out at 8ºC for 43 days. Oxidation numbers rose slowly during the open-package shelf life study and surpassed 2 mg MDA/kg by day 39 of storage. Fatty acid profiles remained stable throughout the open-package study. Microbial numbers began to rise in samples treated only with STPP at day 15 of the test. These rolls reached 10⁶ CFU/g by day 28. The other treatments did not show microbial growth until day 28, and reached 10⁶ CFU/g on day 37. This strongly suggests that treatments with nitrites retard microbial growth, regardless of the amount of albacore meat used. Psychrotrophic bacteria were the first group to be detected in all samples. The second study consisted of a sensory evaluation based on a nine-pt. hedonic scale with 120 panelists. In this study, all albacore rolls were treated with 0.3% STPP and 150 ppm nitrates, and the only variable was the level of albacore meat used (82% and 88%). Panelists were asked to rate textural, flavor, smoke, saltiness, oiliness and moistness properties, as well as purchase intent at a given price point. Overall, the low meat level (82%) was rated to have stronger smoke flavor, higher oiliness and higher moistness values while the high meat level (88%) was rated as having a firmer texture. When asked about willingness to buy, the consumers showed high interest in purchasing the product for themselves.
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