常见咨询问题

TA.new plus 质构仪参数

1.  力量感应元：20kg(1kg、 5kg、10kg、50kg、100kg可选）。

2.  力量感应元校准误差：误差小于0.1%。

3.  力量感应元可以通过国际标准砝码进行验证和校正，同时具有样品称重功能(天平)：精度0.1g，校准砝码国家计量单位认证证书。

4.  位移精度：≤0.001mm。

5.  测试移动距离：0～400mm。

6.  检测速度：0.01～45mm/s，可由软件设定控制。

7.  速度解析度：0.001mm/s，精度优于0.1%。

8.  数据采集率：可调 20、50、100、200组/秒，如有需要可调至400组/秒。

9.  测试方法：单次测试、黏度测试、全质构分析测试(TPA)、松弛测试、衰减度测试、循环测试等六种，数据分析时不需另外撰写分析程序，用户可直接勾选所要的参数，软件即可自动计算结果。

全质构分析(TPA)名词解释

硬度 (Hardness) :

        直接反应口感的一项指标，在质地剖面分析中，直接影响咀嚼性 (Chewiness)、胶着性(Chewiness)及凝聚性(Cohesiveness)。

脆度 (Fracturability) :

        针对有酥脆外壳(外皮)者样品所有，多数样品都无法测得此参数，一般而言此参数若无法测得，软件会自动隐藏。

粘性 (Adhesiveness) :

        样品经过加压变形之后，样品表面若有黏性，会产生负向的力量。在食品领域可以解释为黏牙性口感。

弹性 (Springiness) :

       食物在第一咬结束与第二口开始之间可以恢复的高度。

咀嚼性 (Chewiness) :

        咀嚼性被定义为胶着性x弹性。可以解释为咀嚼固体食物所需的能量。难以准确测量，因为咀嚼涉及压缩、剪切、穿刺、粉碎、撕裂、切割等，另外也与口腔状况有关(唾液分泌、体温)。这个参数主要用在固体、半固体的口感描述上。

胶着性 (Gumminess) :

        胶着性被定义为硬度x凝聚力。半固体食品的一个特点就是具有低硬度，高凝聚力。因此这项指标应该用于描述半固体食品的口感上。

粘聚性 (Cohesiveness) :

       凝聚力被定义为第一压缩与第二压缩正受力面积的比值。抗拉伸强度是凝聚力的一种体现，如果凝聚较佳样品，显示探头也较容易保持干净。通常测试凝聚力相较脆性、咀嚼性和胶着性为较次要参数。

回复性 (Resilience) :

        韧性是一种测量样品如何恢复变形的参数，包括了速度和力量两方面。 定义为第一次下压时，形变目标之前面积与形变目标之后的面积比值。在量测的时候需要注意样品的恢复状况，一般而言会使用一个较慢的测试速度已达到使样品有足够时间恢复状况。也能确保这个特性的准确性。

AACC 74-09面包硬度测试（美国谷物化学协会）

Measurement of Bread Firmness by Universal Testing Machine

Procedure

Preparation of sample

 Total sample thickness is 25mm. Loaves may be sliced either mechanically or by hand, 25mm or 12.5mm thick. See Notes 1 and 2.

 1. For 12.5-mm thick slices: use two slices stacked together for test sample; discard two or three two or three end slices with heels of loaf.

 2. For 25-mm thick slices:use one slice for test sample and discard heel slices of loaf.

Method

 1. Position upper crosshead limit so that compression plunger is 1mm above center surface of sample.

 2. Position lower crosshead limit at 40% compression (10-mm compression depth).

 3. Set crosshead speed (rate of compression)at 100mm/min.

 4. Set chart speed at 500mm/min (5:1 ratio of chart to crosshead extension).

 5. Set full scale (range) at 1kg or desired range.

 6.Center prepared sample under compression plunger, avoiding any irregular or nonrepresentative areas of crumb.

 7.Compress sample approximately 10mm(40% compression). Force reading will be measured at 25% compression but curve will be drawn beyond 25% to 40%.

 8. Return compression plunger to upper limit position.

 9.Discard test slice.

10.Repeat steps 6-9 until desired number of slices have been evaluated for firmness. Evaluate six slices have been evaluated for firmness. Evaluate six slices per loaf.

Pasta and Noodle Cooking Quality-Firmness

Apparatus

1. Texture analyzer，equipped with 5-kg weigh beam, data-integration system, and plastic(lexan preferred) tooth as described in Ref.4.

2. Hotplate, variable output.

3. Air oven.

Procedure

Instrument setup

 1.Calibrate data-integration system with tooth in place. Use either 1-kg or full-load scale.

 2.Set crosshead speed to 10.0mm/min.

 3. Position upper crosshead limit so that tooth clears sample by 1-3mm.

 4. Position lower crosshead limit so that tooth is 0.5mm from bottom plate.

 5. Set recorder speed at 100mm/min.

Preparation of sample

 1. Place 300ml distilled water into 500-ml breaker (one for each sample) and bring to rolling boil on hotplate. See Note 1. Maintain one extra breaker of boiling distilled water for makeup purposes. Graduated breakers are useful for adjusting volume of cooking are useful for adjusting volume of cooking water during test.

 2. Weigh two 25-g portions of pasta or noodles for each sample being tested. See Note 2. Break pasta long goods or noodles into pieces approximately 5 cm long to permit free movement in boiling cooking medium.

Cooking time

 1. Determine cooking time for each product by adding one of 25-g portions to breaker containing 300 ml boiling distilled water.

 2. Start timer counting. Stir sample to make sure that pieces are separated.

 3. Boiling stops when pasta is added. After cooking water has returned to rolling boil, maintain this condition throughout test. Partially cover breaker to help reduce evaporation and maintain consistent temperature. Use extra breaker of boiling water to maintain cooking water volume at least at 90% of original volume.