Browning, Starch Gelatinization, Water Sorption, Glass Transition, and Caking Properties of Freeze-dried Maca ( Lepidium meyenii Walpers) Powders.

IF 16.4 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Accounts of Chemical Research Pub Date : 2020-11-20 eCollection Date: 2020-01-01 DOI:10.5458/jag.jag.JAG-2020_0008

Alex Eduardo Alvino Granados, Kiyoshi Kawai

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Abstract

The browning, gelatinization of starch, water sorption, glass transition, and caking properties of freeze-dried maca ( Lepidium meyenii Walpers) powders were investigated and compared with a commercial maca powder. The freeze-dried maca powders had lower optical density (browning) and higher enthalpy change for starch gelatinization than the commercial maca. This resulted from a difference in thermal history. The equilibrium water contents of the freeze-dried maca powders were higher than those of commercial maca at each water activity ( a _w ) because of differences in amorphous part. The glass transition temperature ( T _g ) was evaluated by differential scanning calorimetry. There was a negligible difference in the anhydrous T _g (79.5-80.2 ºC) among the samples. The T _g -depression of freeze-dried maca powders induced by water sorption was more gradual than that of the commercial maca due to a difference in water insoluble material content. From the results, critical water activity ( a _wc ) was determined as the a _w at which T _g becomes 25 ºC. There was negligible caking below a _w = 0.328. At higher a _w , the degree of caking remarkably increased with a large variation depending on the samples. The degree of caking could be described uniformly as a function of a _w / a _wc . From these results, we propose an empirical approach to predict the caking of maca powders.

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冷冻干燥玛卡（Lepidium meyenii Walpers）粉末的褐变、淀粉糊化、吸水性、玻璃化转变和结块特性。

研究了冻干玛卡（Lepidium meyenii Walpers）粉末的褐变、淀粉糊化、吸水性、玻璃化转变和结块特性，并与商用玛卡粉进行了比较。与商品玛咖相比，冻干玛咖粉的光密度（褐变）更低，淀粉糊化焓变更高。这是由于热历史不同造成的。由于无定形部分的差异，在每个水活度（a w）下，冻干玛咖粉的平衡含水量都高于商品玛咖粉。差示扫描量热法评估了玻璃化转变温度（T g）。不同样品的无水 T g（79.5-80.2 ºC）差异微乎其微。由于不溶于水的物质含量不同，冻干玛咖粉吸水引起的 T g 下降比商品玛咖粉更缓慢。根据研究结果，临界水活度（a wc）被确定为 T g 变为 25 ºC 时的 a w。a w = 0.328 以下的结块可以忽略不计。当 a w 越高时，结块程度显著增加，不同样品之间的差异很大。结块程度可统一描述为 a w / a wc 的函数。根据这些结果，我们提出了一种预测玛咖粉结块的经验方法。

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来源期刊

Accounts of Chemical Research 化学-化学综合

CiteScore

31.40

自引率

1.10%

发文量

312

审稿时长

2 months

期刊介绍： Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance. Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.