饼干中氧化稳定性检测方案(氧化分析仪)

APPLICATION NOTEF&F-0-001-2013/A2 OXIDATION STABILITY IN BISCUITS Oxidation Stability on Biscuits Reference： EURACHEM GUIDELINES Tested with VELP Scientifica OXITEST Oxidation Stability Reactor (Code F30900248) Introduction Britain has been the first biscuits producers in history， during the 10* century. It was the bread of the sailors who needed durable bread to eat during their long voyages： made without moisture， it wasa hard dough bread， flat shape with all holes in the surface and it was cooked twice， “bis-cooked". During the 19" century， the formula started to include also butter and sugar to make them delightful， becoming a sort ofluxury food. Today the consumption of biscuits is widely spread because they include a range of different shapes and flavors，ingredients and formulas， that make them suitable for all the consumers’needs. Oxidation Stability in Food One of the most important quality alteration of food is due to oxygen absorption by the unsaturated fatty acids， free oresterified. The auto-oxidation of fats is a chemical reaction promoted by oxygen， light， high temperatures， metal tracesand， sometimes，enzymes. OXITEST can determine the oxidation stability on various sample types， without the need for preliminary fat separation. OXITEST Principle OXITEST speeds up the oxidation process because of the two accelerating factors， temperature and oxygen pressure，according to the most common applications. The instrument measures the absolute pressure change inside the two chambers， monitoring the oxygen uptake byreactive components in the sample and automatically generates an IP value. IP Definition： IP stands for Induction Period and it is the time required to reach the starting point of oxidation， corresponding to either alevel of detectable rancidity or a sudden change in the rate of oxidation. The longer the Induction Period， the higher the stabilityagainst oxidation over time. Sample Biscuits formula F1 Fat labeled value： 18.1 g/ 100 g， composed by 12.1 g of unsaturated fatty acids and 6.0 g of saturated fatty acids Biscuits formula F2 Fat labeled value： 18.3 g / 100 g composed by 9.3 g of unsaturated fatty acids and 9.0 of saturated fatty acids Equipment and Chemicals Analytical balance， 3 decimals Silicone grease ● Grinder ●·Oxygen， purity grade 5.0 Sample Preparation Store the samples at room temperature. Grind the biscuits to a suitable finesse and put 10 grams of homogeneous sample directly on the surface of the titaniumsample holder， by using a spatula. In each reaction chamber (A and B)， place 3 sample holders containing the sample for a total of 30 g， grinded biscuits. Analysis Procedure Grease the O-rings with silicon grease and set them in their position. Close the chambers with the titanium covers andturn the discharge valves in open position. Set the following conditions on the OXISoft TM software： Temperature： 100°C Oxygen Pressure： 6 bars When the temperature set is reached inside the chambers， close the discharge valves and start loading oxygen.Data acquisition is automatically started by the software. Typical Results on Biscuits Each biscuit sample has been monitored four times. At the end of the oxidation tests， the IP of every run is calculated bythe software OXISoftTM. It is possible to elaborate the oxidation curves obtained for each kind of biscuit. Sample Weight (g) Set Point (bars) Set Point (°C) IP (hh：mm) Line Biscuits F1 30.000 6.00 100.0 54：41 Biscuits F1 30.000 6.00 100.0 56：40 Biscuits F1 30.000 6.00 100.0 51：50 Biscuits F1 30.000 6.00 100.0 57：52 Biscuits F2 30.000 6.00 100.0 100：09 Biscuits F2 30.000 6.00 100.0 96：31 Biscuits F2 30.000 6.00 100.0 92：35 Biscuits F2 30.000 6.00 100.0 92：15 Repeatability Test With OXISoftM， it is possible to create a repeatability test for each analysis， in order to obtain the average， standarddeviation and relative standard deviation of the results. For repeatability test， it is necessary to analyze the same quantity of the sample in duplicate or more， at the same valuesof temperature and pressure. In the table below the results are summarized： Sample IP average (hh：mm) SD (hh：mm) RSD % Biscuits F1 55：15 2：38 4.8 Biscuits F2 95：22 3：43 3.9 RSD value must be <5% in order to obtain good results. Formula Comparison With OXISoft M，it is also possible to easily compare the obtained IP values， of different formulations but tested at thesame condition， and identify the most stable one. Biscuits F2 Conclusion The results obtained by OXISoft M and the formula comparison function clearly discriminate the biscuits’resistance tooxidation， although the total fats percentage of their formulations is very similar. Biscuits F1 have a shorter IP value， hence a lower oxidation stability. This is related to their higher content of unsaturated fatty acids that have a higher oxidation kinetic compared tosaturated fatty acids. In conclusion， biscuit F2 results significantly more stable against oxidation. Benefits of OXITEST are： Test is made directly on the whole sample No need for preliminary fat separation of the sample Resistant titanium chamber Time saving analysis， if compared to the traditional methods Especially designed for R&D， Product Development and Quality Control labs Many investigations available through the software OXISoftTM： 1. Repeatability test： a series of tests run on the same sample or standard to verify its IP period， to calculateaccuracy and repeatability of the data 2. Freshness test： to verify the quality of different lots， for example of the same raw material， and compare them 3. Formula comparison： to identify the most stable formula of a finished product， under the same conditions 4. Packaging comparison： for testing which packaging maintains the product in the freshest condition 5. IP during ageing： to obtain a graph of the decrease of the product IP during the shelf-life period 6. Estimated shelf life： to have a prediction of oxidation stability during the shelf life. Copyright C VELP Scientifica. All rights reserved.No part of this publication may be reproduced or transmitted in any form or for any purpose without the express permission of VELP.VELP Scientifica， Italy Tel：+ Fax： + www.velp.com 英国从10 世纪开始是历史上第一个饼干生产国。这种饼干为了水手们在长途航行中需要吃的耐久的食物。这种饼干不含水分，是一种硬面团面包，形状扁平，表面有许多洞，经过两次后备。在19 世纪，配方中开始添加包括黄油和糖，使他们更加受欢迎，渐渐成为一种奢侈的食物。今天，饼干的消费被广泛地传播，因为它们包括一系列不同的形状和口味，成分和配方，使他们适合所有消费者的需要。食品中的氧化稳定性其中最重要的影响食物质量变化之一由于氧吸收了不饱和脂肪酸，油脂的自氧化是一种由氧气、光、高温、金属痕迹影响，有时还跟酶促反应有关。OXITEST 可以测定各种样品的氧化稳定性，不需要进行初步的油脂分离OXITEST 加速氧化过程是通过加速温度和氧气压力这两个因素。该仪器测量两个腔室内的绝对压力变化，监测样品中反应性成分的耗氧量，并自动生成一个IP 值。IP 定义:IP 代表诱导期，是达到氧化起始点所需要的时间，对应于可检测到的不饱和脂肪酸或氧化速率的突然变化。诱导期越长，抗氧化稳定性越好。本文研究了不同饱和脂肪酸和非饱和脂肪酸的配比与氧化稳定性之间的关系。