Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97331-6602, U.S.A.
J Food Sci. 2018 Feb;83(2):340-348. doi: 10.1111/1750-3841.14025. Epub 2018 Jan 16.
Moisture adsorption isotherms and storability of dried hazelnut inshells and kernels produced in Oregon were evaluated and compared among cultivars, including Barcelona, Yamhill, and Jefferson. Experimental moisture adsorption data fitted to Guggenheim-Anderson-de Boer (GAB) model, showing less hygroscopic properties in Yamhill than other cultivars of inshells and kernels due to lower content of carbohydrate and protein, but higher content of fat. The safe levels of moisture content (MC, dry basis) of dried inshells and kernels for reaching kernel water activity (a ) ≤0.65 were estimated using the GAB model as 11.3% and 5.0% for Barcelona, 9.4% and 4.2% for Yamhill, and 10.7% and 4.9% for Jefferson, respectively. Storage conditions (2 °C at 85% to 95% relative humidity [RH], 10 °C at 65% to 75% RH, and 27 °C at 35% to 45% RH), times (0, 4, 8, or 12 mo), and packaging methods (atmosphere vs. vacuum) affected MC, a , bioactive compounds, lipid oxidation, and enzyme activity of dried hazelnut inshells or kernels. For inshells packaged at woven polypropylene bag, MC and a of inshells and kernels (inside shells) increased at 2 and 10 °C, but decreased at 27 °C during storage. For kernels, lipid oxidation and polyphenol oxidase activity also increased with extended storage time (P < 0.05), and MC and a of vacuum packaged samples were more stable during storage than those atmospherically packaged ones. Principal component analysis showed correlation of kernel qualities with storage condition, time, and packaging method. This study demonstrated that the ideal storage condition or packaging method varied among cultivars due to their different moisture adsorption and physicochemical and enzymatic stability during storage.
Moisture adsorption isotherm of hazelnut inshells and kernels is useful for predicting the storability of nuts. This study found that water adsorption and storability varied among the different cultivars of nuts, in which Yamhill was less hygroscopic than Barcelona and Jefferson, thus more stable during storage. For ensuring food safety and quality of nuts during storage, each cultivar of kernels should be dried to a certain level of MC. Lipid oxidation and enzyme activity of kernel could be increased with extended storage time. Vacuum packaging was recommended to kernels for reducing moisture adsorption during storage.
评估了俄勒冈州产的巴塞洛那、雅姆希尔和杰斐逊等品种榛子带壳和去壳坚果的干燥吸湿等温线和贮藏性，并对其进行了比较。实验吸湿数据符合古根海姆-安德森-德博（GAB）模型，表明雅姆希尔带壳和去壳坚果的吸湿性能低于其他品种，这是由于碳水化合物和蛋白质含量较低，但脂肪含量较高。使用 GAB 模型估计，巴塞洛那、雅姆希尔和杰斐逊带壳和去壳坚果的安全水分含量（干基）分别为 11.3%和 5.0%、9.4%和 4.2%、10.7%和 4.9%，以达到核水分活度（a ）≤0.65。贮藏条件（2℃，相对湿度 85%至 95%，10℃，相对湿度 65%至 75%，27℃，相对湿度 35%至 45%）、时间（0、4、8 或 12 个月）和包装方法（大气与真空）影响了榛子带壳和去壳坚果的水分含量（MC）、a 、生物活性化合物、脂质氧化和酶活性。对于用编织聚丙烯袋包装的带壳榛子，在 2 和 10℃时，带壳和去壳榛子（壳内）的 MC 和 a 增加，但在 27℃时下降。对于去壳榛子，脂质氧化和多酚氧化酶活性随着贮藏时间的延长而增加（P<0.05），真空包装样品的 MC 和 a 在贮藏过程中比大气包装样品更稳定。主成分分析表明，核品质与贮藏条件、时间和包装方法有关。本研究表明，由于不同品种在贮藏过程中的水分吸附、理化和酶稳定性不同，理想的贮藏条件或包装方法也有所不同。
