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[原文翻译] 猪的好口感-酸味

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发表于 2013-5-20 13:29:15 | 显示全部楼层 |阅读模式
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                                                 猪的好口感-酸味
                                                               20111121
                        作者:Eugeni Roura;Marta Navarro  译者:刘彩红
     养猪业中酸值是必须研究的一个项目,也有许多文献是关于这个话题的.通常关于酸作用模式的出版文献过多地强调”体外”试验,比如说酸的抗菌能力以及对饲料酸结合力的影响.另外,据称幼畜体内的酸可以降低胃液的pH值,加强改善饲料中的酶消化。然而,一方面,酸效应对饲料消化的影响的相关数据报道是稀缺的,缺乏一致性。另一方面,算对适口性和饲料采食量的潜在影响力在很大程度上被忽略。这篇报告的目的是为了总结目前已知的关于猪对酸的口感的看法。
     很多拿手养猪人都会赞同酸味对猪是重要的感觉。这一点也不奇怪,当我们认识到大多数可能适用于猪的野外自然饲料原料都含有丰富的有机酸。例如,短链氨基酸被发现存在于不同的水果中,比如柑橘,野生浆果,苹果和西瓜中,也包括西兰花,胡萝卜,蘑菇,土豆和西红柿(表1)。柠檬酸酸是最常见的酸,主要存在于水果、块茎和蔬菜中。其次是苹果酸和酒石酸。其它商业常用的酸中,有少量的富马酸,乙酸和甲酸也常常被发现在自然界中常见的食物中。
                                                表1. 食物水果中常见的酸(1)
柠檬酸
苹果, , 香蕉, 越橘, 蓝莓, 杂交草莓, 樱桃, 越橘,醋栗果, 接骨木浆果, 无花果, 醋栗, 葡萄柚,葡萄,猕猴桃, 金橘,柠檬, 酸橙, 罗甘莓, 橙皮, 橙子,桃, 梨, 菠萝, 覆盆子, 草莓, 橘子, 杨氏草莓, 豆类, 花椰菜 胡萝卜, 土豆,西红柿, 大黄.
苹果酸
苹果, , 香蕉, 黑莓, 蓝莓, 杂交草莓, 樱桃, 越橘, 葡萄干, 接骨木, 无花果, 醋栗, 柚子, 葡萄, 柠檬,酸橙, 杨梅, 油桃, 越橘, 橙子, 百香果, , , 菠萝, 李子, 玫瑰果, 榅桲,沙拉, 草莓, 杨氏草莓, 豆类, 花椰菜, 胡萝卜,豌豆, 土豆,大黄, 西红柿.
酒石酸
鳄梨, 香蕉, 樱桃, 葡萄干, 柚子, 葡萄, 柠檬, 酸橙, 梨, 李子.
反丁烯二酸
苹果, 豆类,胡萝卜, 蘑菇, 西红柿.
琥珀酸
苹果, 蓝莓, 樱桃, 葡萄干, 草莓,豆类, 胡萝卜, 西红柿.
乙酸
香蕉 (微量).
甲酸
香蕉 (微量)
乳酸
苹果
(1)     水果和蔬菜中数量明显多的酸,采用粗体表示。酸在每种水果或蔬菜中的数量依据品种、成熟度和收获季节的变化而呈现不同数目。
              有机酸可能有两种影响食欲的感官成分,体感和口感。口腔中的体感是通过三叉神经感知的。从表面上看,跨膜离子通道TRRA1负责感受辛辣,作为疼痛通路(也可以叫伤害性感受器)的一部分。一些酸刺激TRRA1。弱酸,如醋酸,丙酸,甲酸,乳酸在中性pH环境中仅仅部分分离,可能会透过细胞膜,酸化神经元胞质,并刺激伤害性感受器,导致辛辣感和疼痛。然而,强酸如柠檬酸和酒石酸,在三叉水平上是惰性的,没有或者轻微地引起辛辣反应(Wang等, 2011).因此,弱酸(如醋酸,丙酸,甲酸和乳酸)可能会导致猪的厌恶反应。
          发酸味被称为酸的感知反应,主要通过舌头的味蕾感受,味蕾通过味觉感受细胞和颅神经VII(鼓索),IX (舌咽神经) 和X (迷走神经)将味觉兴奋体连接到味觉皮层. 蛋白质复合物 PKD1L3 和 PKD2L1被激活应答,并负责酸味感受体。然而,因为未分离酸渗透到味觉细胞中,饲料的氢离子浓度和它的酸味感觉之间仅仅有一个中度相关性。Danilova等199年对猪进行的电生理学研究中发现在各种广泛的潜在味觉兴奋剂中,柠檬酸和抗坏血酸引起了猪舌神经的最大反应,但是这些反应与任何行为测试无关。最近,Suarez等2010年使用系统方法评估了饲料添加有机酸和一些盐如何影响偏食性(图1)。这些结果显示,1%的添加水平,柠檬酸和酒石酸显著地改善了饲料的偏食性,而辛酸、醋酸、磷酸和甲酸引起了厌恶反应。与此相反,添加甲酸钾盐没有任何的厌恶反应。在实际生产中,甲酸和甲酸结合物以及丙酸有一致的效应,它们被报道出能减少饲料的采食量。事实上,市场的大部分已经转移到有机酸盐的使用上,弱酸引起了辛辣反应,直至影响采食量,这是市场一部分的沉思。
       总之,柠檬酸和酒石酸引发了猪先天就有的酸味喜爱,而且它们的辛辣感觉是微弱的,依然是可以忽略的。它们在饲料中是建议使用的。相反,弱酸如醋酸,甲酸或丙酸引发了躯体的疼痛感受通道,导致对饲料的厌恶反应。除非是使用盐或者其他包衣形式,否则这些酸因为影响适口性而不能使用在猪的饲料中。
图1.gif

图1 仔猪对日粮中酸盐的偏食性(已经经作者同意复制,作者: Suarez等, 动物科学期刊 Vol. 88, E-Suppl. 2: 651, 2010).
*星号表示平均值与中性值50%差异显著(P<0.05)。


英文


The good taste of pigs (part III): let it be sour
21-Nov-2011
Eugeni Roura Marta Navarro
  The use of acids in pig production has merited a lot of research and an even higher amount of literature around it. Often publications regarding the mode of action of acids have overemphasized the relevance of “in vitro” tests such as the antimicrobial activity or the effect on the acid binding capacity of feeds. In addition, acids in young animals have been claimed to decrease gastric pH and hence improve enzymatic digestion of feeds. However, in general the data reported on the effect of acids on feed digestibility is scarce and lacks consistency. On the other hand the potential impact of acids on palatability and feed intake has been overlooked to a great extent. The objective of this report is to summarize what is known today regarding sour taste perception in pigs.
Many people involved in “hands on” pork production will agree that sour taste is of particular relevance in pigs. This is not surprising when we realize that a lot of natural food sources potentially available to pigs in the wild are rich in organic acids. For example, short chain acids are widely found in a variety of fruits like citrus, wild berries, apples and watermelon but also avocados, broccoli, carrots, mushrooms, potatoes and tomatoes (Table 1). Citric acid is the most common of the acids found in fruits, tubers and vegetables followed by malic and tartaric. Among other commercially available acids, small amounts of fumaric, acetic, and formic are also found in foods naturally available in the wild.
Table 1. Main organic acids present in fruits and vegetables (1)
Citric
Apple, Apricot, Bananas, Bilberry, Blueberries, Boysenberries, Cherries, Cranberries,Currants, Elderberries, Figs, Gooseberries, Grapefruit, Grapes, Kiwifruit, Kumquat,Lemons, Limes, Loganberry, Orange Peel, Orange, Peaches, Pears, Pineapples, Raspberry, Strawberries, Tangerine, Youngberries, Beans, Broccoli, Carrots, Potatoes,Tomatoes, Rhubarb.
Malic
Apples, Apricots, Bananas, Blackberries, Blueberries, Boysenberries, Cherries, Cranberries, Currants, Elderberries, Figs, Gooseberries, Grapefruit, Grapes, Lemons, Limes, Loganberry, Nectarine, Orange peel, Orange, Passion fruit, Peaches, Pears, Pineapples, Plums, Rosehip, Quinces, Salad, Strawberries, Youngberries, Beans, Broccoli, Carrots,Peas, Potatoes, Rhubarb, Tomatoes.
Tartaric
Avocados, Bananas, Cherries, Currants, Grapefruit, Grapes, Lemons, Limes, Pears, Plums.
Fumaric
Apples, Bean, Carrots, Mushrooms, Tomatoes.
Succinic
Apples, Blueberries, Cherries, Currants, Strawberries, Beans, Carrots, Tomatoes.
Acetic
Bananas (traces).
Formic
Bananas (traces).
Lactic
Apples.
(1) Fruits and vegetables with significant quantities of the acid are shown in bold and italics. The relative amount of acids in each fruit or vegetable vary widely with the variety, degree of ripeness and seasonal changes of the harvest.

Organic acids have two sensory components that may affect appetence: somatosensing and taste. Somatosensing in the oral cavity is perceived through the trigeminal nerve. Seemingly, the transmembrane ion channel TRPA1 is responsible for perception of pungency as part of the pain pathway (referred to as a nociceptor). Several acids stimulate TRPA1. Weak acids such as Acetic, Propionic, Formic and Lactic are only partially dissociated at neutral pH and may cross the cell membrane acidifying the neuronal cytosol and stimulate the nociceptor leading to pungency and pain. However, strong acids such as Citric and Tartaric, were inert at a trigeminal level resulting in no or insignificant pungency responses (Wang et al., 2011). Thus, weak acids (e.g. Acetic, Propionic, Formic and Lactic) are likely to result in aversive responses in pig.
Sour taste is known for acid perception and is sensed mainly through tongue’s taste buds that connect taste agonists to the gustatory cortex via taste sensory cells and the cranial nerves VII (Chorda Tympany), IX (Glossofaryngeal) and X (Vagus). Protein complexes PKD1L3 and PKD2L1 have been proposed as responsible for sourness perception. However, there is only a moderate correlation between the hydrogen ion concentration of a food and its perceived sourness due to the penetration of non-dissociated acids inside the taste cells. Electrophysiological studies in pigs performed by Danilova et al. (1999) found citric and ascorbic acids to elicit the largest responses in pig taste nerves among a wide group of potential taste agonists but these responses were not linked to any behavioural tests. Recently, Suarez et al. (2010) reviewed in a systematic manner how feed addition of organic acids and some salts affects preferences (Figure 1). The results showed that, at 1% inclusion level, Citric and Tartaric acids significantly improved feed preferences while Caproic, Caprilic, Acetic, Phosphoric and Formic resulted in an aversive response. In contrast, the potassium salt of Formic acid did not show any sign of aversion. In trials performed under more practical conditions Formic acid and combinations of Formic and Propionic acids have consistently been reported to decrease feed intake. The fact that a good part of the market has shifted to the use of the salts of organic acids, may be a reflection, in part, of the effect of weak acids on pungency and ultimately feed intake.
In conclusion, Citric and Tartaric acids trigger an innate sour taste that is attractive to pigs while their pungency is smooth and remains unnoticed. Their use in feeds is recommended. On the opposite side, weak acids such as Acetic, Formic or Propionic trigger the somatic pain pathway and result in aversive responses to feed. Unless presented in the form of some salts or coated, the use of such acids should be avoided in piglet feeds due to palatability issues.

Figure 1. Dietary preferences of acids en salts in piglets. (Reproduced with permission of the authors: Suarez et al., J. Anim. Sci. Vol. 88, E-Suppl. 2: 651, 2010).

*The asterisks indicate that the means are significantly (P<0.05) different than the neutral value of 50 %.

英文来源:pig333.com


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发表于 2013-5-20 17:32:32 | 显示全部楼层
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