Food Specific Heat (Choi-Okos)
Compute a food's specific heat by the Choi-Okos equations, cp = 4.18·Xwater + 1.55·Xprotein + 1.71·Xfat + 1.42·Xcarbohydrate + 0.91·Xash (kJ/kg·K), from the component mass fractions. Since water has a very high specific heat, wetter foods heat and cool more slowly. It is essential in computing the heat loads of cooking, refrigeration and freezing. Enter the water, protein, fat, carbohydrate and ash fractions.
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Calor específico de alimento (Choi-Okos)
Quanta energia é preciso para aquecer ou resfriar um alimento? Depende do seu calor específico (cp), que varia conforme a composição. As equações de Choi-Okos calculam o cp somando as contribuições de cada componente, ponderadas pela fração mássica: cp = 4,18·Xágua + 1,55·Xproteína + 1,71·Xgordura + 1,42·Xcarboidrato + 0,91·Xcinzas (kJ/kg·K). Repare que a água tem o maior coeficiente (4,18), de longe — por isso alimentos úmidos (frutas, hortaliças, carnes) têm cp alto e aquecem/resfriam devagar, exigindo mais energia e tempo, enquanto alimentos secos ou gordurosos respondem mais rápido. O cp entra diretamente no cálculo de cargas térmicas de cozimento, pasteurização, refrigeração e congelamento (acima do ponto de congelamento; abaixo, o calor latente do gelo domina). É uma propriedade fundamental no projeto de trocadores de calor e câmaras frias da indústria de alimentos. Informe as frações de água, proteína, gordura, carboidrato e cinzas.
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