Studies on the storage stability of yayik butter

Yayik butter produced by churning of yoghurt is one of the popular traditional dairy products of Turkey. In this study, yayik butter was divided into four lots. Two lots were stored with a daylight lamp at 4 and 20°C (L4; L20) and the other two lots were stored at 4 and 20°C in dark (D4: control; D20) for 60 days. Then, the oxidative stability of yayik butter was evaluated. The end of self life was determined from sensory data. Generally acceptability was negatively correlated with peroxide value (PV), free fatty acid (FFA), thiobarbituric acid (TBA) and titratable acidity (TA). While general acceptability of control samples (D4) was between 8.26 ± 0.20 and 7.80 ± 0.10, those of L20 sample was lower than 3.00 (dislike moderately) on 60th day. As a result of decrease detected for sensory quality, the storage process was ended. L20 sample was evaluated as unacceptable on the 60th day and the evaluation result of this sample was accepted as the limiting value. The limiting values of TA, FFA and PV, TBA were determined as 0.14 ± 0.01%, 1.93 ± 0.11 mg KOH/g oil, 0.80 ± 0.007 meq O₂/g oil and 0.37 ± 0.02 mg malonaldehyde/kg butter in this yayik butter.     

Effect of extrusion conditions and storage temperature on texture,colour and acidity of butter

The effect of extruder shear rate (500, 750, 1125, 1500 and 1750/s), feed temperature (5, 7, 10, 13 and 15 °C) and storage temperature (5, 7, 10, 13 and 15 °C) on the acid value, colour (L*, a* and b*values) and texture (hardness and adhesiveness) of organic butter was examined. The optimised conditions in terms of extruder shear rate, feed temperature and storage temperature were 1345/s, 13 °C and 7 °C, respectively. At the optimised conditions; the predicted responses were determined as hardness 42.5 g/cm, work softening 67.2%, adhesiveness 42.5 gf/cm, acid value 3.4 mg KOH/kg and L* value 99.57.     

Quality of Malaysian cocoa butter during storage

Malaysian pure prime pressed and deodorised cocoa butters were obtained from local cocoa grinders and analysed for quality deterioration. Approximately 5 kg of each sample was packed in corrugated paper boxes lined with low‐density polyethylene plastic material of thickness 73.2 µm. The water vapour transmission rate and gas transmission rate (for oxygen) of the plastic material were 3.21 g m^?2 day^?1 (37.8 °C, 90 ± 2% RH) and 71.57 cm³ m^?2 day^?1 (23.0 °C, 0% RH) respectively. The butters were stored at 15 ± 4 °C and 70 ± 4% RH for up to 24 months. Samples were taken every 2 months and analysed for free fatty acid content, saponification value, iodine value, refractive index and peroxide value. The findings indicated that the free fatty acid content, iodine value and peroxide value of both types of cocoa butter increased with storage duration. The other parameters showed no significant changes. However, the free fatty acid content and peroxide value after 24 months of storage were still below the limits specified in Malaysia. Therefore we conclude that both types of Malaysian cocoa butter are still in good condition after 24 months of storage, with minimal quality deterioration. Copyright © 2004 Society of Chemical Industry     

Effect of electron beam irradiation on quality indicators of peanut butter over a storage period

Electron beam (e-beam) irradiation is an effective non-thermal processing step for the reduction of Salmonella in peanut butter. The objective of this study was to evaluate the effects of e-beam irradiation on quality indicators of peanut butter. Peanut butter samples were exposed to a range of e-beam doses and examined over a 14-day period at 22 °C. Colour analysis (L^∗, a^∗, b^∗), spreadability, peroxide values (PV) and thiobarbituric acid reactive substances test (TBARS) for lipid oxidation were monitored, fatty acid and amino acid profiles were verified and protein degradation was determined by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). Changes in colour, PV, and TBARS were observed as e-beam dose increased. No significant changes in spreadability were observed (P > 0.05). When applied to peanut butter, e-beam irradiation will produce significant changes in quality indicators; future studies should include sensory evaluation and consumer acceptance studies.     

Effect of aminoethoxyvinylglycine and low-pressure storage on the post-storage production of aroma volatiles by Golden Delicious apples

Golden Delicious apple fruits untreated (control) or treated pre-harvest with the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) were stored at 2°C under either ambient pressure or low pressure (6.7 kPa; LPS). The production of aroma volatiles during post-storage periods at 20°C was measured on fruits stored for 3, 5, 7 and 9 months. Aroma production of AVG- or LPS-treated fruits immediately after storage was considerably lower. However, after 14 days at 20°C, aroma production almost reached values for control fruits (AVG fruits had to be treated with 50 μl C₂H₄ litre^?1). After the longer storage this effect of a post-storage period at 20°C declined gradually and finally was almost absent. Only a post-storage period at 2°C in a normal atmosphere followed by a period at 20°C was now able to partially revive long-stored fruits from this ‘residual’ effect of AVG or LPS. It is suggested that changes in the sensitivity of fruits to C₂H₄ are responsible for the observed decline in aroma production.     

Effect of adding shea butter stearin and emulsifiers on the physical properties of cocoa butter

The aim of this study was to assess the feasibility of shea butter stearin (SBS) as cocoa butter equivalent (CBE). In this work, the optimal ratio of SBS and cocoa butter (CB) was evaluated by the solid fat content and deviation solid fat content. Emulsifiers added to SBS and CB blends were first screened based on β polymorph level, and mixture regression experiment was designed to obtain the optimized compound emulsifiers ratio, finally the characterization of shea butter chocolate was evaluated by sensory evaluation and texture profile analysis (TPA). The best compatibility was obtained when the mixture ratio of SBS and CB was 20:80, where ΔSFC within a range of 1.5 was shown. The appropriate compound emulsifiers were soy lecithin: polyglycerol polyricinoleate: Tween 60 = 1:1:1. Both sensory evaluation and TPA test showed SBS and CB blends could improve the taste and texture of chocolate with proper emulsifiers addition.     

牛油火锅底料冷藏储存过程中品质变化

以牛油火锅底料为研究对象,测定在冷藏(4℃)条件下其水分、酸价、过氧化值、辣椒素类似物、脂肪酸组成及相对含量随时间变化情况。结果表明:样品的水分、酸价、过氧化值随时间延长均呈上升趋势,且氧化速度逐渐加快。辣椒素类似物含量随时间延长而下降,且降解速度逐渐减慢。气相色谱质谱分析得出不饱和脂肪酸含量下降,低级脂肪酸含量升高。因此,控制牛油火锅底料油脂在冷藏期间的劣变有利于维持产品品质,延长其货架期。     

乳粉对可可脂/代可可脂结晶特性的影响

为提高巧克力制品品质,研究了乳粉种类及添加比例对可可脂及代可可脂结晶特性的影响。采用差示扫描量热仪(DSC)和X-射线衍射(XRD),考察不同添加比例的全脂乳粉、脱脂乳粉和乳清粉对可可脂和代可可脂(基于棕榈油和棕榈仁油)在非等温条件下结晶行为的影响。结果表明:全脂乳粉或乳清粉的加入会降低可可脂和代可可脂的结晶和熔化温度,其中全脂乳粉的影响最为显著;脱脂乳粉的加入则表现为提高可可脂和代可可脂的结晶和熔化温度。添加脱脂乳粉或乳清粉后代可可脂仍然稳定在β′晶型,而全脂乳粉的加入则导致代可可脂冷却结晶后β晶型的出现。高比例的全脂乳粉或乳清粉的加入均会导致调温后可可脂结晶中亚稳定态β′晶型的出现,即阻碍了可可脂稳定态晶型β晶型的形成,影响了巧克力的调温效果,而脱脂乳粉的添加对可可脂的稳定晶型无影响。     

精炼工艺对可可脂品质的影响

为探究精炼工艺对可可脂品质的影响,对可可脂毛油进行脱胶、脱酸和脱色,分析精炼过程中可可脂理化指标、微量成分的变化情况。结果表明:可可脂精炼后,酸价下降,过氧化值升高,色泽变浅、透明度升高,微量成分生育酚(288. 15～155. 75 mg/kg)、植物甾醇(3 621. 82～2 551. 01mg/kg)、总酚(216. 76～106. 41 mg/kg)、可可碱(130. 89～78. 67 mg/kg)和咖啡因(311. 77～202. 31 mg/kg)的含量均显著降低;在15～30℃,精炼油固体脂肪含量(92. 75%～18. 17%)高于毛油(86. 27%～3. 73%),此外,精炼油的熔化焓值(84. 79 J/g)和结晶焓值(64. 18 J/g)均高于毛油的熔化焓值(78. 45 J/g)和结晶焓值(59. 63 J/g),说明可可脂精炼油比毛油具有更高的热稳定性。因此,精炼工艺能够显著影响可可脂的品质,要重视适度加工在今后的应用。     

Effect of cocoa butter structure on oil migration

Oil migration from a high oil content filling into adjacent chocolate causes changes in product quality. The objective of this study was to quantify the oil migration from a cream filling system into cocoa butter, which provided a model for the behavior of chocolate-enrobed confectionery products with a soft, creamy center. Magnetic resonance imaging (MRI) was used to monitor spatial and temporal changes of liquid lipid content. A multislice spin echo pulse sequence was used to acquire images with a 7.8 ms echo time and a 200 ms repetition time using a 1.03 T Aspect Imaging MRI spectrometer. Samples were prepared as a 2-layer model system of cocoa butter and model cream filling. Three methods were used to prepare the cocoa butter: static, seeded, and sheared. Samples were stored at 25 °C for a time frame of 56 d. The rate of oil migration was quantified by a kinetic expression based on the linear dependence of oil uptake by cocoa butter and the square root of the time. Samples showed distinctly different rates of oil migration, as evidenced by quantitative differences in the kinetic rate constant. Practical Application: This work will be helpful to elucidate the influence of crystallization process and structural properties such as crystal nanostructure and crystal habit on the migration of oil through a crystalline fat matrix.     

酶解方式对黄油酶解物风味物质的影响

采用SPME和GC-MS方法比较了不同酶解方式对黄油酶解物中风味物质的影响。黄油单酶酶解物、双酶酶解物中分别鉴定得到12种、16种,14种（同时加酶）和16种（顺序加酶）风味物质;黄油酶解物中的主要风味物质为酮类、脂肪酸类物质。两种酶解方式的双酶酶解物中的主要风味物质相似,均为中、短碳链的脂肪酸,但含量有所不同。因此,不同酶解方式获得的黄油酶解物中风味物质的种类与含量差别较大。      

黄曲霉污染稻谷贮藏期间典型挥发性成分的变化

采用HS—SPME/GC—MS检测了黄曲霉污染稻谷贮藏期间的挥发性成分并获取其总离子流图。结合TurboMass和NIST Search软件分析GC—MS总离子流图,得出黄曲霉污染稻谷的挥发性成分有26种,其中醛类5种,醇类6种,酮类1种,烃类9种,酯类1种,杂环类1种,有机酸1种,胺类1种。依据黄曲霉在稻谷中的分解代谢和物质转化,推测出2-羟基-丙酰胺和庚醛是黄曲霉污染稻谷的典型挥发性成分,可作为判别黄曲霉污染稻谷的典型标志物,也可为基于挥发性代谢产物早期快速鉴别黄曲霉污染稻谷的器件开发提供试验依据。     

Effect of cultivars and deep freeze storage on saponin content of white asparagus spears (Asparagus officinalis L.)

A method was developed to prepare saponin samples of asparagus spears by Solid Phase Extraction (SPE) and to analyse these extracts by High Performance Thin Layer Chromatography (HPTLC). We chose six asparagus cultivars grown in Germany and measured total saponin contents of approximately 0.14–0.80 g kg⁻¹ fresh weight (fw). Among these six cultivars grown under eaqual conditions ‘Grolim’ showed the highest levels of saponins while ‘Huchels Alpha’ had the lowest contents. The other four cultivars gave intermediate levels. Asparagus stored at −18°C subsequently resulted in maintenance of saponins during 20 weeks of storage. Up to six saponins were found in the extracted samples, but three of them were the main compounds with approximately 90% of the total saponin content. Two main saponins (AS 1 and AS 2) were characterised by mass spectrometry as protodioscin and methyl-protodioscin.     

Effects of milk fat, cocoa butter, or selected fat replacers on flavor volatiles of chocolate ice cream

Selected volatile compounds of chocolate ice creams containing 0.6, 4.0, 6.0, or 9.0% milk fat or containing 2.5% milk fat, cocoa butter, or one of three fat replacers (Simplesse, Dairy Lo, or Oatrim) were analyzed by gas chromatography and gas chromatography-mass spectrometry using headspace solid-phase microextraction. The headspace concentration of most of the selected volatile compounds increased with decreasing milk fat concentration. Fat replacers generally increased the concentration of volatiles found in the headspace compared with milk fat or cocoa butter. Few differences in flavor volatiles were found between the ice cream containing milk fat and the ice cream containing cocoa butter. Among the selected volatiles, the concentration of 2,5-dimethyl-3(2-methyl propyl) pyrazine was the most highly correlated (negatively) with the concentration of milk fat, and it best discriminated among ice creams containing milk fat, cocoa butter, or one of the fat replacers.     

采收期对黄秋葵果实品质及风味物质的影响

为确定黄秋葵果实的合理采收期,以‘绿箭’品种为试材,研究果实的生长发育特性及主要营养成分及风味物质的变化。结果表明:黄秋葵果实以花后7~9 d生长速率较高,干物质含量较低,但花后11 d果实不溶性膳食纤维方显著升高,而可溶性膳食纤维则迅速降低;随采收期延迟,果实蛋白质、氨基酸、总糖、可溶性糖及灰分含量呈降低趋势,而总酚、黄酮含量则以花后11 d采收较高,分别比花后7 d采收的果实增加了14.10%和5.16%,尽管花后11 d采收的果胶含量较7 d时降低了12.08%,但其果实鲜质量增加近1倍。虽然不同采收期果实风味物质主要成分基本相同,但相对含量存在显著差异。综合分析确定,黄秋葵传统鲜食以花后7~9 d采收为宜,而利用其功能成分进行精深加工,则以花后11 d采收较好。     

牙鲆冷藏过程中肌肉挥发性风味成分的变化

为研究牙鲆不同贮藏阶段挥发性风味物质的组成特征,采用固相微萃取-气质联用技术测定牙鲆4℃冷藏条件下肌肉挥发性风味物质的变化情况,并利用主成分分析法和聚类分析法对挥发性物质的组成差异进行分析。结果表明:在冷藏牙鲆肌肉中共检测出66种主要的挥发性物质,包括醛、醇、酮、烃、酯和胺类化合物等。主成分分析结果表明,不同贮藏时间牙鲆肌肉的特征风味物质组成不同,其中贮藏初期以醛、酮和醇类化合物为主,在第0天和第3天时鱼肉样品的特征风味物质主要是己醛、壬醛、苯甲醛、2-壬酮、2-乙基己醇、1-戊烯-3-醇等;贮藏后期以胺类化合物为主,在贮藏12d时鱼肉样品的特征风味物质主要是甲基乙胺、N-己基甲胺、十九胺等。聚类分析发现,不同贮藏阶段鱼肉样品的风味轮廓可各自聚为一类。