One of the major quality aspects of our food supply is its content of vitamins and minerals. From a biological point of view, we eat to survive, and the pattern of our nutrient requirements has developed during a long evolutionary process in which man has adapted to his environment. Although certain food process, such as cooking, are indeed very old, it is only within the last 150 years that we have begun to consume significant part of our food in a factory-processed form. 

    Our modern processed food supply has contributed enormously to the public health status of the population. Certain nutritional diseases, which were common in parts of the United States 50 years ago, such as pellagra, have all but disappeared. A recent ten-states nutritional survey demonstrated that while nutritional deficiencies did exist, they were minimal compared to what existed prior to the modern era of nutrition and food technology.Consider that it is now possible to eat a diet balanced in all types of foods at any time of year and in any geographical location. 

    At the same time, modern process technology has also introduced its share of problems. Sometimes this has been a result of inadequate knowledge, but tragic cases of illness and even death have occurred where essential nutrient value has been lost because of ignorance, carelessness, and lack of adherence to “good manufacturing practice.” In the past, new food processes have seldom been assessed for their contribution to nutrient loss or retention.

    Multiple processes, such as freezing of reconstituted dehydrated foods, may lead to benefits in process scheduling, but they may also lead to higher than normal losses of vitamins. New forms of food products, such as intermediate moisture food, may lead to accentuated problems of vitamin stability. A food product, to have acceptable nutritional quality, Should generally be capable of providing those nutrients normally characteristic of its food group. 

    It is the purpose of this lesson to summarize the available information on the requirements of vitamins and minerals for human.
 
    Vitamin and Mineral Requirements and Allowances 
 
    In order to understand whether a specific treatment of a specific food leads to acceptable nutrient quality, it is necessary to have an understanding of both human requirements and the amount of a specific nutrient present in the food after normal preparatory procedures. 

    The concentrations of many of the key nutrients are given for fresh and cooked foods in USDA Handbook No.8. Although data in this compilation are occasionally inaccurate, they afford the only major source of information apart from direct analysis of the product in question.In many instances, inaccuracies are caused by analytic procedures of insufficient specificity, and users of these data should be especially cognizant of the appropriateness of the methodology

    The presently accepted status of human dietary requirements is well summarized in the Recommended Dietary Allowances (RDA) of the Food and Nutrition Board, National Academy of Sciences-National Research Council. 

    Since both males and females of different age classes have been assigned different RDA’s, it is simpler to consider a mean value for each nutrient. Mean values for men and women ages 23—50 years are summarized in Table 5-1. It is appropriate deal with nutrients that have neither established nor approximated RNA’s in a quantitative fusion. However, one should remain aware of the fact they are essential.
 
    Enrichment, Restoration, and Fortification 
 
    The addition of nutrients to foods may be undertaken for a variety of purposes. Definitions of the various terms associated with addition of nutrients are: 

    1.     Restoration: Addition to restore the original nutrient content. 

    2.     Fortification: Addition of nutrients in amounts significant enough to render the food a good to superior source of the added nutrients. This may include addition of nutrients not normally associated with the food or addition to levels above that in the unprocessed food. 

    3.     Enrichment: Addition of specific amounts of selected nutrients in accordance with a standard of identity as defined by the United States Food and Drug Administration. 

    The Joint Policy Statement by the Council on Foods and Nutrition of the American Medical Association and the Food and Nutrition Board of the National Academy of Sciences-National Research Council, published in August 1968, endorses continuation of nutrient addition programs. The specific endorsement states.

    The enrichment of flour, bread, degerminated corn meal, corn grits, whole grain corn meal. And white rice (with thiamine, riboflavin, niacin, and iron); the retention or restoration of thiamine, riboflavin, niacin, and iron in processed food cereals; the addition of vitamin D to margarine; fluid skimmed milk, and nonfat dry milk; and the addition of vitamin A to margarine; fluid skimmed milk, and nonfat dry milk; and the addition of iodine to table salt; the protective action of fluoride against dental caries is recognized, and the standardized addition of fluoride is endorsed in areas in which the water supply has a low fluoride content.

    In addition, the Council on Foods and Nutrition and the Food and Nutrition Board in the same policy statement continue to endorse the addition of nutrients to foods under all of the following circumstance: 

    1. When the intake of the nutrients is below the desirable level in the diets of a significant number of people. 

    2. When the food used to supply the nutrient is likely to be consumed in quantities that make a significant contribution to the diet of the population in need.           

    3. When the addition of the nutrient is not likely to create an imbalance of essential nutrients. 

    4. When the nutrient added is stable under proper conditions of storage and use. 

    5. When the nutrient is physiologically available to the consumer. 

    6. When there is reasonable assurance against excessive intake to a level of toxicity.  

    人类食物供应的主要质量问题之一是它的维生素和矿物质的含量。人类摄取食物从生物学角度来看是为了生存。他们在长期的进化过程中已适应了周围环境，逐步形成了营养要求的模式。尽管有些食品加工工艺(如烹调)的确非常古老，但人类开始大量消费工业加工食品则只是l50年来的事。

    现代加工食品的供应对大众的公共健康状况有巨大的贡献。某些营养性疾病(如糙皮病)50年前曾在美国部分地区很普遍，而现在已差不多消失了。最近十个州的营养调查表明，缺乏营养的状况确实存在，但与现代食品营养新技术出现之前的状况相比是微不足道的。仔细想一想，如今在世界任何地区都有可能在一年四季中吃到各类食物都能达到平衡的膳食。

    与此同时，现代食品加工技术也带来了它本身的一些问题。有时，这些问题是由于认识不足造成的，但也有在必需营养素效价因不懂、忽视或不遵守“食品生产卫生作业规程”而失去的情况下，出现生病甚至死亡的悲剧。过去，人们对新的食品加工方法影响营养素损失和保留的问题很少进行查定。重复加工，例如干制食品复水后冷冻，可能对生产作业计划的安排有好处，但也会造成维生素损失超出正常的水平。新型食品如半干半潮食品可能会使维生素稳定性问题突出出来。营养质量合格的食品一般应能提供该类食品正常所特有的营养素。

    本课的目的是综述现有有关维生素和矿物质的人体需要量。

    维生素和矿物质的需要量和标准量

    要了解具体会品的特定加工方法是否能达到合格的营养质量，就必须了解人体的营  养素需要量和食物经正常加工手续之后的具体营养素含量。

    美国农业部手册第8卷给出许多重要营养素在新鲜食品和烹调食品中的含量。尽管  此汇编资料中的数据往往不准确，但除了直接分析所论产品以外，它是唯一重要的资料  来源。在许多情况下，误差来源于分析方法不够专门化。因此数据用户应彻底弄清所用分析方法是否恰当。

    目前公认的人体营养需求状况在美国科学院全国科学研究委员会食品营养研究会的  推荐膳食标准(RDA)中作了全面的概括。

    由于给不同年龄组的男性和女性已经指定了不同的推荐膳食标准，所以对每种营养  素估计一个平均值就很方便。表5—1归纳了年龄23、50岁男性、女性的营养素平均需要  量。表中还适当列出了那些既没有用定量方式制定的，也没有近似估计的膳食标准的营  养素。尽管如此，也要知道这些营养素同样是人体必需的营养素。

    (美)食品营养研究会对必需营养素的分类 

    营养素 单位 23—50岁正常健康男性和女性的平均膳食标准

    有推荐膳食标准量的营养素热量蛋白质维生素A 维生素E抗坏血酸(Vc)叶酸烟酸核黄素(VB2)硫胺素(VB1)维生素B6维生素B12 CaPIFeMgZn有近似估计膳食标准量的营养素CuK泛酸既无推荐又无近似估计膳食标准量的营养素胆碱、维生素D、维生素K、氯化物、Cr，Co、F、Mn、Mo、Ni、Se、Si、Sn、V 。   KcalGIUIUmgµgmegmgmgmgµgmgmgµgmgmgmg  mgmgmg             23505145001445400161.41.22.03.08008001151432515  22.55-10  

    增补、复原和强化

    向食品中添加营养素有各种各样的目的。与添加营养素有关的各种技术名词的定义是：

    1．复原：添加营养素以恢复食品中原有营养素的含量。

    2．强化：添加相当数量的营养素足以使食品成为该添加营养素丰富以至于非常丰富的来源。这种情况可能包括加入正常情况下该食品所没有的营养素或加入的营养素的量超过未加工食物中的含量。

    3．增补：按照美国食品药物管理局规定的统一标准加入一定数量的选定营养素。    美国医学协会食品营养委员会和美国科学院全国科学研究委员会食品营养研究会的联合政策声明(1968年8月发表)批准了扩大营养素添加方案，具体批注指明：

    “面粉、面包、去胚玉米粉、玉米胚乳粗粉、整粒玉米粉和精白米的增补(用硫胺素、核黄素、烟酸和铁)；谷物加工食品中硫胺素、核黄素、烟酸和铁的保留或复原；牛乳、脱脂乳和脱脂乳粉中维生素D的添加；人造奶油、脱脂乳和脱脂乳粉中维生素A的添加；食盐中碘的添加；确认氟化物对龋齿病的防护作用，批准在水源含氟化物量低的地区添加规定的氟化物量。”

    此外，食品营养委员会和食品营养研究会还在同一政策声明中接着批注了在所有下列情形下营养素的添加：

    I．在人数相当多的膳食中，该营养素的摄入量低于所要求的标准时；

    2．当用以提供该营养素的食物往往要大量消费才能对急需它的人的膳食起明显作用时；

    3．当添加的营养素不会造成必需营养素的不平衡时；

    4．当添加的该营养素在恰当的贮藏和使用条件下是稳定的时候；

    5．当该营养素对消费者是生理上可用之时；

    6．当能确保摄入量低于产生毒性的水平时。