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.  

    人類食物供應(yīng)的主要質(zhì)量問題之一是它的維生素和礦物質(zhì)的含量。人類攝取食物從生物學(xué)角度來看是為了生存。他們在長期的進(jìn)化過程中已適應(yīng)了周圍環(huán)境，逐步形成了營養(yǎng)要求的模式。盡管有些食品加工工藝(如烹調(diào))的確非常古老，但人類開始大量消費工業(yè)加工食品則只是l50年來的事。

    現(xiàn)代加工食品的供應(yīng)對大眾的公共健康狀況有巨大的貢獻(xiàn)。某些營養(yǎng)性疾病(如糙皮病)50年前曾在美國部分地區(qū)很普遍，而現(xiàn)在已差不多消失了。最近十個州的營養(yǎng)調(diào)查表明，缺乏營養(yǎng)的狀況確實存在，但與現(xiàn)代食品營養(yǎng)新技術(shù)出現(xiàn)之前的狀況相比是微不足道的。仔細(xì)想一想，如今在世界任何地區(qū)都有可能在一年四季中吃到各類食物都能達(dá)到平衡的膳食。

    與此同時，現(xiàn)代食品加工技術(shù)也帶來了它本身的一些問題。有時，這些問題是由于認(rèn)識不足造成的，但也有在必需營養(yǎng)素效價因不懂、忽視或不遵守“食品生產(chǎn)衛(wèi)生作業(yè)規(guī)程”而失去的情況下，出現(xiàn)生病甚至死亡的悲劇。過去，人們對新的食品加工方法影響營養(yǎng)素?fù)p失和保留的問題很少進(jìn)行查定。重復(fù)加工，例如干制食品復(fù)水后冷凍，可能對生產(chǎn)作業(yè)計劃的安排有好處，但也會造成維生素?fù)p失超出正常的水平。新型食品如半干半潮食品可能會使維生素穩(wěn)定性問題突出出來。營養(yǎng)質(zhì)量合格的食品一般應(yīng)能提供該類食品正常所特有的營養(yǎng)素。

    本課的目的是綜述現(xiàn)有有關(guān)維生素和礦物質(zhì)的人體需要量。

    維生素和礦物質(zhì)的需要量和標(biāo)準(zhǔn)量

    要了解具體會品的特定加工方法是否能達(dá)到合格的營養(yǎng)質(zhì)量，就必須了解人體的營  養(yǎng)素需要量和食物經(jīng)正常加工手續(xù)之后的具體營養(yǎng)素含量。

    美國農(nóng)業(yè)部手冊第8卷給出許多重要營養(yǎng)素在新鮮食品和烹調(diào)食品中的含量。盡管  此匯編資料中的數(shù)據(jù)往往不準(zhǔn)確，但除了直接分析所論產(chǎn)品以外，它是唯一重要的資料  來源。在許多情況下，誤差來源于分析方法不夠?qū)ｉT化。因此數(shù)據(jù)用戶應(yīng)徹底弄清所用分析方法是否恰當(dāng)。

    目前公認(rèn)的人體營養(yǎng)需求狀況在美國科學(xué)院全國科學(xué)研究委員會食品營養(yǎng)研究會的  推薦膳食標(biāo)準(zhǔn)(RDA)中作了全面的概括。

    由于給不同年齡組的男性和女性已經(jīng)指定了不同的推薦膳食標(biāo)準(zhǔn)，所以對每種營養(yǎng)  素估計一個平均值就很方便。表5—1歸納了年齡23、50歲男性、女性的營養(yǎng)素平均需要  量。表中還適當(dāng)列出了那些既沒有用定量方式制定的，也沒有近似估計的膳食標(biāo)準(zhǔn)的營  養(yǎng)素。盡管如此，也要知道這些營養(yǎng)素同樣是人體必需的營養(yǎng)素。

    (美)食品營養(yǎng)研究會對必需營養(yǎng)素的分類 

    營養(yǎng)素 單位 23—50歲正常健康男性和女性的平均膳食標(biāo)準(zhǔn)

    有推薦膳食標(biāo)準(zhǔn)量的營養(yǎng)素?zé)崃康鞍踪|(zhì)維生素A 維生素E抗壞血酸(Vc)葉酸煙酸核黃素(VB2)硫胺素(VB1)維生素B6維生素B12 CaPIFeMgZn有近似估計膳食標(biāo)準(zhǔn)量的營養(yǎng)素CuK泛酸既無推薦又無近似估計膳食標(biāo)準(zhǔn)量的營養(yǎng)素膽堿、維生素D、維生素K、氯化物、Cr，Co、F、Mn、Mo、Ni、Se、Si、Sn、V 。   KcalGIUIUmgµgmegmgmgmgµgmgmgµgmgmgmg  mgmgmg             23505145001445400161.41.22.03.08008001151432515  22.55-10  

    增補(bǔ)、復(fù)原和強(qiáng)化

    向食品中添加營養(yǎng)素有各種各樣的目的。與添加營養(yǎng)素有關(guān)的各種技術(shù)名詞的定義是：

    1．復(fù)原：添加營養(yǎng)素以恢復(fù)食品中原有營養(yǎng)素的含量。

    2．強(qiáng)化：添加相當(dāng)數(shù)量的營養(yǎng)素足以使食品成為該添加營養(yǎng)素豐富以至于非常豐富的來源。這種情況可能包括加入正常情況下該食品所沒有的營養(yǎng)素或加入的營養(yǎng)素的量超過未加工食物中的含量。

    3．增補(bǔ)：按照美國食品藥物管理局規(guī)定的統(tǒng)一標(biāo)準(zhǔn)加入一定數(shù)量的選定營養(yǎng)素。    美國醫(yī)學(xué)協(xié)會食品營養(yǎng)委員會和美國科學(xué)院全國科學(xué)研究委員會食品營養(yǎng)研究會的聯(lián)合政策聲明(1968年8月發(fā)表)批準(zhǔn)了擴(kuò)大營養(yǎng)素添加方案，具體批注指明：

    “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補(bǔ)(用硫胺素、核黃素、煙酸和鐵)；谷物加工食品中硫胺素、核黃素、煙酸和鐵的保留或復(fù)原；牛乳、脫脂乳和脫脂乳粉中維生素D的添加；人造奶油、脫脂乳和脫脂乳粉中維生素A的添加；食鹽中碘的添加；確認(rèn)氟化物對齲齒病的防護(hù)作用，批準(zhǔn)在水源含氟化物量低的地區(qū)添加規(guī)定的氟化物量。”

    此外，食品營養(yǎng)委員會和食品營養(yǎng)研究會還在同一政策聲明中接著批注了在所有下列情形下營養(yǎng)素的添加：

    I．在人數(shù)相當(dāng)多的膳食中，該營養(yǎng)素的攝入量低于所要求的標(biāo)準(zhǔn)時；

    2．當(dāng)用以提供該營養(yǎng)素的食物往往要大量消費才能對急需它的人的膳食起明顯作用時；

    3．當(dāng)添加的營養(yǎng)素不會造成必需營養(yǎng)素的不平衡時；

    4．當(dāng)添加的該營養(yǎng)素在恰當(dāng)?shù)馁A藏和使用條件下是穩(wěn)定的時候；

    5．當(dāng)該營養(yǎng)素對消費者是生理上可用之時；

    6．當(dāng)能確保攝入量低于產(chǎn)生毒性的水平時。