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世界人口的增长

时间:2015-10-22 18:49:50 来源:www.ukthesis.org 作者:英国论文网 点击联系客服: 客服:Damien
世界人口的增长
研究背景
 
随着世界人口的增长,许多社会难以分配足够的资源,如植物、动物和鱼类,满足人类的像生存和身体健康这样的基本需求,这是至关重要的问题。我们的营养状况、健康状况、生理和心理能力取决于我们所吃的食物和我们如何吃它(联合国粮农组织,2005)。许多社会很难提供优质的食物。食品安全是食品质量的一个基本要求,这意味着消费的食品必须远离污染物,伪品,天然毒素或可能使食物在急性或慢性的基础上对健康有害的其他物质。如果不遵守,食源性疾病将会发生。
 
食源性疾病可以来源于与病毒或细菌病原体,有毒物质和寄生虫(联合国,2005)的食物。因此,这些致病性和非致病性细菌被发现于皮肤,鳃和肠鱼。与海鲜相关的疾病是全世界重要的公共健康问题,因为鱼对人类的营养非常重要。海鲜有牵连10-25%的发达国家食源性疾病暴发(联合国粮农组织,2005)。
 
组胺中毒是最常见的食源性生物胺引起的问题。它由多种食物组成,包括生鱼有革兰氏阴性肠细菌如摩氏摩根氏,克雷伯氏菌属和肠杆菌属的组氨酸脱羧活性(阿尔瓦雷斯等人,2006)。在无毒剂量下,食源性组胺可引起不能容忍的症状,如腹泻,低血压,头痛,瘙痒和潮红。仅仅75毫克组胺,在正常膳食中普遍存在的量,可以诱发没有组胺不耐受历史的健康人产生多种组胺症状,除了存在有毒理学特性后,还可以是食品质量的一个指标。
 
As world populations grow
 
研究背景-Background of the Study
    
As world populations grow, many societies struggle to allocate sufficient resources such as plants, animals and fishes to meet human basic needs which are vital for survival and good health. Our nutritional status, health, physical and mental faculties depend on the food we eat and how we eat it (FAO of the United Nation, 2005). Many societies are challenged to provide good quality food. Safety of food is a basic requirement of food quality which implies that food for consumption must be safe from contaminants, adulterants, naturally occurring toxins or any other substance that may make food injurious to health on an acute or chronic basis. If not complied, food borne diseases arise.
 
Food-borne diseases can originate from foods contaminated with viruses or bacterial pathogens, toxic substances and parasites (FAO of the United Nations, 2005). Accordingly, these non-pathogenic and pathogenic bacteria have been found on the skin, gills and intestines of fish . Illnesses associated with seafood are an important public health concern worldwide because fish are of great importance for human nutrition. Seafood has been implicated in 10-25 percent of food-borne disease outbreaks in developed countries (FAO of the United Nations, 2005).
 
Histamine poisoning is the most common food borne problem caused by biogenic amine (Wohrl et al., 2004). It is formed in a variety of foods, including raw fishes by the histidine decarboxylation activity of gram-negative enteric bacteria such as Morganella morganii, Klebsiella spp and Enterobacter spp (Alvarez et al., 2006). At nontoxic doses, food borne histamine can cause intolerance symptoms such as diarrhea, hypotension, headache, pruritus, and flushes. Just 75 milligram (mg) of histamine, a quantity commonly present in normal meals, can induce symptoms in the majority of healthy persons with no history of histamine intolerance (Wohrl et al., 2004) in affirming that histamine, aside for having toxicological properties, could also be an indicator of food quality.
 
Around the world, one most common cause of food intoxication is the histamine present in fish. This food borne intoxication is caused by seafood and usually presents as an allergic reaction (Gonzaga et al., 2009). Some cases of histamine poisoning occurred in February 2006 in Tainan Prefecture, Southern Taiwan where histamine poisoning caused illness in the three victims due to ingestion of dried milkfish (Tsai et al., 2007). In Japan, Canada, United States and other countries with high dietary intake of fish reported outbreak in histamine poisoning in fish. Most of these outbreaks were caused by fish containing high levels of histamine (Malison et al., 1987). In addition, Bakovic (2008) cited that in June 2007, several cases of histamine poisoning were reported but prompt medical intervention has saved the lives of the victims.
 
In the Philippines, there are about 60 reported food-borne outbreaks for the period of 1995-2004. Some of these food intoxications were caused by staphylococcal enterotoxins, paralytic shellfish poisoning (PSP) toxins and histamine (Azanza, 2004).
 
It is for these reasons that fish sectors in General Santos City are working closely with the national government to convince the European Union (EU) to adopt a more liberal screening process that will guarantee good quality of food specifically fish products. General Santos City as the Tuna Capital of Asia provides the Generals and pampers its guest with tons and tons of different fish species as its main product. It accounts for a big chunk in the global tuna market. From its single airport, huge amounts of tuna and other fish species are sent to local markets and worldwide. To ensure food safety, exported fishes undergo laboratory analysis; however, fish and fishery products delivered to its local markets has no routinary procedure to check histamine level of raw fishes, which constitute a serious risk for human health. In this case, the researcher intend to conduct a survey to determine possible presence and level of histamine in commercial fish samples from the main public market of General Santos City and to assess compliance with the Food Standards Code. Findings of the study can serve as basis for a local food safety program.
 
问题的申明-Statement of the Problem
 
This study aims to determine the histamine level of selected raw fish species sold at the main public market of General Santos City.
 
Specifically, this study seeks to answer the following questions:
 
1. What is the level of histamine in raw fish species sold at the main public market of General Santos City, namely:
 
Decapterus maruadrsi Temminck & Schlegel (Round scad)
Selar crumenophthalmus Bloch (Bigeye Scad Atulai)
Oreochromis niloticus Linnaeus (Tilapia)
Chanos chanos Forsskal (Milkfish)
2. Do the levels of histamine level in selected raw fish species sold in the main Public market of General Santos City conforms to the standard set by the Bureau of Fisheries and Aquatic Resources (BFAR) and European Union (EU)?
 
概念和理论框架-CONCEPTUAL AND THEORETICAL FRAMEWORK
 
It is theorized in this research that level of histamine in selected fish species for analysis will exceed the allowable limit of this compound. The elevated level of histamine in these products will be due to the following uncontrollable factors once fishes are sold in the market. These factors include temperature, storage time and condition. Since, the government lack the resources to constantly monitor the level of histamine, the researcher conceptualize this theory by conducting a test on the level of histamine in selected fishes sold in the Public Market of General Santos City. The diagram below shows the conceptual framework of this research.
 
 
This study is limited to the determination of histamine level of raw fish species sold at the main public market of General Santos City using the fluorometric method, regardless of temperature storage and sources. The fish samples to be considered for histamine analysis will be Decapterus maruadsi, Selar crumenophthalmus,Oreochromis niloticus and Chanos chanos. Three trials with three replications of sample per species will be considered for the analysis. Sampling will be conducted for three consecutive weeks. The analysis will be conducted by the researcher and laboratory analyst of the Bureau of Fisheries and Aquatic Resources (BFAR) Laboratory, Lagao, General Santos City.
 
研究意义-Significance of the Study
 
Excessive levels of histamine in fish and fishery products constitute a serious risk for human health. It is appropriate to adopt community level measures of fishery products to ensure effective and uniform protection for all the members of society. This study will assess the histamine level of most consumed raw fish species sold at the main public market of General Santos City. The result of the study will serve as basis for the authorities to carry out necessary checks, particularly the determination of histamine level in fish and fishery products in public markets to safeguard public health and provide them the foods that are safe and unadulterated. This study is also necessary to update the standards set by Bureau of Fisheries and Aquatic Resources (BFAR) for raw fresh fishes.
 
Moreover, the knowledge gained from this study will notify both fish sellers and consumers that hygienic quality of fish should be instituted to control the histamine level of fish and fishery products within the standard.
 
术语定义-Definition of Terms
 
The following terms are operationally defined for the purpose of understanding the meaning of the terms used in the study.
 
Chanos chanos Forsskal. This refers to a species of fish is commonly known as milkfish reaching a length of about 150 cm (about 5 ft) and a weight of 14 kg (30 lb), with a slender large body, silver scales, a greenish back, and a white belly. It has big eyes, a small, toothless mouth, and a large, deeply forked tail.
 
Decapterus maruadsi Temminck & Schlegel. This refers to a species of fish commonly known as Round Scad which has an elongated body, upper jaw reaching to just below eye brow margin, teeth in jaws in a single series, those of upper jaw confined to anterior end of jaw and vomerine teeth in a transverse strip.
 
Fish. This refers to fresh or saltwater fish which is intended for human consumption.
 
Foodborne disease outbreak. This refers to the occurrence of two or more cases of a similar illness (fish poisoning) resulting from the ingestion of fish.
 
Histamine. This refers to the white crystalline compound (C5H9N3) formed when bacteria produce decarboxylase, which acts on free histidine in the fish muscle. The level of this compound in raw fish samples will be determined.
 
Histidine. This refers to a naturally occurring chemical that is present in larger quantities in some fish than in the others.
 
Histidine decarboxylase. This refers to an enzyme produced by certain bacteria during growth. This reacts with free histidine, resulting to the formation of histamine.
 
Oreochromis niloticus Linnaeus. This refers to a species of fish commonly known as tilapia which has laterally flattened bodies that range from about 10 to 30 cm (about 4 to 12 in) in length and usually sold at the main public market of General Santos City.
 
Potentially hazardous food. This refers to a food that is natural or synthetic and that requires temperature control because it is in a form capable of supporting the rapid and progressive growth of infectious or toxigenic microorganisms.
 
Selar crumenophthalmus Bloch. This refers to a species of fish commonly known Bigeye Scad Atulai which has an elongated body, very large eye, upper jaw moderately broad; teeth small and recurved, upper jaw with a narrow band, tapering posteriorly; lower jaw with an irregular single row. This is one of the four fish species to be analyze.
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