Malnutrition during weaning age—when breast milk is being replaced by semi-solid foods—is highly prevalent in children of poor households in many developing countries. While the etiology (病因学) is complex and multifactorial, the immediate causes are recognized as feeding at less than adequate levels for child growth and development, and recurrent infections, including diarrhea, resulting mainly from ingestion of contaminated foods. As a result, many young children, particularly between six months to two years of age, experience weight loss and impaired growth and development. Studies by investigators in various countries have concentrated on traditional food preparation methods and have resulted in offering cheap and practical answers to these problems based on familiar, indigenous and culturally acceptable home processing practices. Two such answers have arisen. Firstly, cereal fermentation is used for reducing the risk of contamination under the existing inappropriate conditions for food preparation and storage in many households. Secondly, a tiny amount of sprouted grains flour is used in preparation of weaning foods as a magic way to lessen the viscosity without decreasing energy density. Cooked foods can be stored longer than fresh foods.
A method to eliminate pathogenic (致病的) bacteria and inhibit their growth during storage of weaning preparations can benefit nutrition and health in young children considerably. Use of fermented foods for feeding children of weaning age appears to be an effective solution. Fermented foods have lower levels of diarrhoeal germ contamination, they are suitable for child feeding, and can be safely stored for much longer periods of time than fresh foods. The practice has been a traditional way of food preservation in many parts of the world. The anti-microbial properties of fermented foods and their relative higher safety—documented since the early 1900’s—have been indicated in a number of studies.
B. In Ghana, it is common to ferment maize dough before cooking it as porridge. In Kenya, cereal-based porridge and milk are traditionally fermented. Preserving milk in the form of yogurt has been known to many households living in hot climate.
C. What are the underlying mechanisms by which fermentation processes help to prevent or reduce contamination A possible answer suggests that during the fermentation process foods become more acid. This explains why diarrhea-causing bacteria are not able to grow in fermented foods as rapidly as in unfermented ones. It is also hypothesized that some of the germs present in the foods are killed or inhibited from growing through the action of antimicrobial substances produced during fermentation. The fermented foods can, therefore, be kept for a longer time compared to fresh ones. It has been shown that while contamination levels in cooked unfermented foods increase with storage time, fermented foods remain less contaminated.
D. Whatever the underlying mechanisms, the fact is that the exercise reduces contamination without adding to the household cost both in terms of time and money. Its preparation is easy. The cereal flour is mixed with water to form a dough which is left to be fermented; addition of yeast (酵母), or mixing with a small portion of previously fermented dough is sometimes needed. The dough can then be cooked into porridge for feeding to the child.Although beneficial, unfortunately the practice is going out of fashion, partly because of current emphasis on the use of fresh foods, particularly for children. For example, a study on the use of fermented foods for young children in Kenya, demonstrated that while foods are still frequently fermented at home for child feeding, their use is becoming less popular, particularly in urban area where commercial products are more available. Clearly they now need to be promoted.
E. Directions:
F. The statements below relate to the passage you have just read. Identify whether they are TRUE or FALSE and mark the corresponding letter (T for True and F for False) on the Answer Sheet with a single line through the center.
阅读下面文字，完成下列问题。物质结构研究的是：我们现实生活的物质世界，是如何由各自独特的微观粒子在不同层次上构成的；千差万别的物质性质是如何由它的微观结构所决定的。近代物质结构理论已经经历了三次大突破。从18世纪后半期开始，人们逐渐弄清了不同的物质是由不同的分子组成的，分子由原子组成，原子由围绕着它作高速旋转的核外电子和原子核组成。原子核虽然只有原子体积的十万亿分之一，但这种小小的原子核又是由中子、质子组成。在20世纪60年代，高能物理实验又发现了许多与质子、中子有强相互作用的新粒子，这些新粒子以及中子、质子、介子等统称强子。高能物理实验表明，强子也有结构，理论物理认为夸克是构成强子的下一层次粒子。理论物理学家把在夸克间传递强相互作用的粒子称为胶子。果然不出所料，这种胶子1979年被美籍华人、著名物理学家丁肇中发现，又一次证明了理论物理的正确。1979年基于基础理论，美国物理学家格拉肖·温伯格和巴基斯坦物理学家萨拉姆做出弱电中的三个中间玻色子W-、W+、Z0的预言，从而荣获诺贝尔物理奖。1983年上半年在日内瓦的质子——反质子对撞机上找到了它们，实验值与理论预期值也高度符合。目前，物质结构理论正面临第四次突破。 “强子也有结构”，强子结构是由（）。
A. 夸克构成
B. 夸克和胶子构成
C. 中子、质子构成
D. 介子构成
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