Effect of roasting conditions on color and volatile profile including HMF level in sweet almonds (Prunus dulcis)

Microwave, oven, and oil roasting of almonds were used to promote almond flavor and color formation. Raw pasteurized almonds were roasted in a microwave for 1 to 3 min, in an oven at 177 °C for 5, 10, 15, and 20 min; and at 135 and 163 °C for 20 min, and in oil at 135, 163, and 177 °C for 5 min and 177 °C for 10 min. Volatile compounds were quantified in the headspace of ground almonds, both raw and roasted, by selected ion flow tube mass spectrometry. Strong correlations were found between L value, chroma, and 5-(hydroxy methyl)-2- furfural; and were independent of roasting method. Raw almonds had lower concentrations of most volatiles than roasted almonds. Conditions that produced color equivalent to commercial samples were 2 min in the microwave, 5 min at 177 °C in the oven, and 5 min at 135 °C in oil. Microwave heating produced higher levels of most volatiles than oven and oil roasting at commercial color. Sensory evaluation indicated that microwave-roasted almonds had the strongest aroma and were the most preferred. Oil-roasted almonds showed significantly lower levels of volatiles than other methods, likely due to loss of these volatiles into the oil. Alcohols such as benzyl alcohols and strecker aldehydes including benzaldehyde and methional were at higher concentrations than other volatiles in roasted almonds. The oxidation of lipids to form alkanals such as nonanal and degradation of sugars to form furan type compounds was also observed. The Maillard reaction contributed to the formation of more of the total volatiles in almonds than the lipid oxidation reaction. PRACTICAL APPLICATION: The level of 5-(hydroxy methyl)-2- furfural (HMF), color, volatile profile, and sensory perception can be used to develop the best roasting method, time, and temperature for almonds. The rate of color development and the production of volatiles differ under different roasting conditions. Based on the color, volatile, and sensory assessments of the 3 almonds, the use of microwave technology as a process for roasting almonds reduces processing time and leads to an almond product with better flavor than oven or oil roasting.     

焙炒对米茶中丙烯酰胺和晚期糖基化终产物的影响

研究焙炒温度、时间、加水量和浸润时间对米茶加工过程中丙烯酰胺(Acrylamide,AA)和晚期糖基化终产物(Advanced glycation end products,AGEs)的影响。结果表明,随着焙炒温度升高和时间的增加,AA和AGEs含量增加,但是当温度高于200℃时AA含量会呈现降低趋势;随加水量增加和浸润时间延长,AGEs含量显著性减少(p<0.05),米茶中的AA含量先降低,在加水量超过10%,浸润时间超过10 min之后升高。在190℃,加水量10%(w/w),浸润10 min,焙炒35 min最适加工条件下AA和AGEs含量分别为141μg/kg和360 AU/g,低于同类产品,正常食用对人体安全。      

焙炒条件对芝麻油中多环芳烃含量的影响

对芝麻进行不同条件焙炒实验,榨取芝麻油,之后对不同焙炒条件下芝麻油中多环芳烃含量进行检测分析。结果表明:随着焙炒时间的延长、焙炒温度的升高,芝麻油中B[a]P、PAH4、PAH16的含量都呈现明显上升趋势;对照国标GB 2716—2005及欧盟No835/2011号法规关于B[a]P和PAH4的限量,芝麻籽的合理焙炒时间不宜超过30 min,焙炒温度不宜超过200℃;焙炒时间为30 min的条件下,焙炒温度在200~240℃之间时,有利于3环物的积累,而焙炒温度达到260℃时,则有利于4环物及重质多环芳烃的积累。     

Lipid analyses of fumigated vs irradiated raw and roasted almonds

The purpose of this study was to compare the effects of propylene oxide (PO) and irradiation treatments on the lipid analyses of raw and roasted almonds. Eight kilograms each of raw and roasted almonds were divided into four batches (2 kg each). Three of the batches were subjected to PO treatment or irradiation treatment with a dose of 6, 10·5 kGy. The untreated batch served as control samples, they were taken from all the batches at three consecutive times during storage (day 0, 8 weeks and 16 weeks) and analysed for iodine number, peroxide value and 2-thiobarbituric acid number. Overall, irradiated almonds incurred a higher variation in lipid stability than PO tested almonds while roasted almonds incurred a higher variation than raw almonds. © 1998 Society of Chemical Industry     

Impact of storage time and temperature on thermal inactivation of Salmonella Enteritidis PT 30 on oil-roasted almonds

Whole Nonpareil variety almonds were inoculated with Salmonella Enteritidis PT 30 and stored at 4 or 23 °C for up to 48 wk. At 1, 12, 24, 37, and 48 wk of storage, almonds were heated by immersion in 121 °C oil. After heating for 0.5 to 2.5 min, almonds were drained, transferred to tryptic soy broth, and mixed with a stomacher prior to plating onto tryptic soy and bismuth sulfite agars. Over the 48 wk of storage, Salmonella declined by 0.5 and 2.1 log CFU/g at 4 and 23 °C, respectively. The survivor inactivation curves were upwardly concave with rapid initial reductions in the levels of Salmonella. For up to 24 wk of storage, the mean counts of the survivors after treatment were not significantly different. The Weibull model predicted 4- and 5-log reductions of Salmonella in 0.85 ± 0.16 and 1.8 ± 0.43 min, respectively, for almonds stored at 4 °C, and in 1.6 ± 0.53 and 3.2 ± 1.0 min, respectively, for almonds stored at 23 °C. Refrigerated storage had little impact on heat resistance of Salmonella that were inoculated on almonds. PRACTICAL APPLICATION: This research provides information of value in performing or evaluating validation studies for thermally processed almonds. The sensitivity of Salmonella to oil roasting is demonstrated during typical commercial almond storage times and temperatures.     

Effect of cultivar and roasting method on composition of roasted soybeans

BACKGROUND: The composition of raw soybeans and the roasting method have an important impact on the quality of roasted soybeans. The objective of the study was to determine the effect of food‐grade soybean cultivars (IA 2064, IA 1008, IA 1008LF, Prairie Brand 299, Asgrow 2247) and roasting method (oil‐ and dry‐roasting) on the composition of roasted soybeans. RESULTS: Moisture content decreased after roasting, with oil‐roasted soybeans having a significantly lower moisture content than the dry‐roasted soybeans. With the exception of the low linolenic acid cultivar (IA 2064), there were no significant differences in total lipid and fatty acid contents of the five cultivars. Oil‐roasted soybeans had significantly higher lipid content than raw and dry‐roasted soybeans owing to the absorption of oil. The soluble sugars and free amino acids contents of the five soybean cultivars were not significantly different. Decreases in the contents of free amino acids, but not soluble sugars, occurred during roasting. Greater reductions were seen in oil‐roasted soybeans because of the higher roasting temperature. CONCLUSION: Roasting method, rather than cultivar, had the greatest effect on the composition of roasted soybeans. The food‐grade soybean cultivars evaluated in this study were similar in composition. Copyright © 2009 Society of Chemical Industry     

Influence of microwave,the combined microwave/hot air and only hot air roasting on the formation of heat-induced contaminants of carob powders

ABSTRACT

This study aims to investigate the effects of microwave, combined microwave/hot air treatment and hot air-only roasting on the formation of heat-induced contaminants of carob powders. Moisture content, water activity and pH values of the product decreased with the increasing roasting time and microwave power, while browning index (BI) and ultraviolet absorbance (UV-A) values were increased. While L and b values of carob powders decreased with increasing the roasting time and microwave power, a and ΔE values were increased. Varying roasting conditions also significantly affected the content of Maillard reaction products (MRPs): 5-hydroxymethylfurfural (HMF) (0.69–28.32 mg/kg dry matter), furfural (<LOD-10.44 mg/kg dm), furan (6.65–10.26 mg/kg dm) and acrylamide (78.69–122.87 µg/kg dm). MRPs contents increased with increasing the roasting time and microwave power. The highest MRPs were found in the samples roasted at 140°C for 20 min by hot air. Significant correlations between the amount of MRPs and colour values were found, especially with a and b values.     

Impact of roasting conditions on the quality and acceptance of the peanut paste

Roasting is the main processing step performed to improve sensory and conservative properties of peanuts. The objective of this study was to evaluate changes in peanut oil and paste during roasting at different temperatures in a conventional oven (80, 110, 140, 170, and 200°C) and microwave. The increase in roasting temperature promoted reduction of L* value, b* value, and increases of a*, K₂₃₂, K_270, and acidity. For alpha (α), gamma (γ), and delta (δ) tocopherols, as well as fatty acids, less degradation were observed at the roasting temperature of 140°C. Paste acceptability greater than 70% was achieved with roasting at 140°C. Based on the results, 140°C was the optimal roasting temperature that achieved the best paste acceptance rates with the smallest changes in oil and tocopherol quality parameters.     

不同熏醅工艺条件对老陈醋中川芎嗪与丙烯酰胺含量的影响

研究了不同熏醅工艺（蒸汽熏醅及炭火熏醅）及不同参数（温度、时间）对醋醅熏制过程中川芎嗪和丙烯酰胺生成量的影响。结果表明,蒸汽熏醅比炭火熏醅能加快美拉德反应的速率;熏醅过程中生成的川芎嗪和丙烯酰胺生成量随着熏醅温度升高和时间延长而增加,但丙烯酰胺比川芎嗪需要更高的熏醅温度（100 ℃以上）才会生成;无论是蒸汽熏醅还是炭火熏醅,90 ℃熏醅至5 d均未检出丙烯酰胺,表明低温熏醅（90 ℃以下）有利于避免丙烯酰胺的生成,在低温熏醅的前提下,蒸汽熏醅比炭火熏醅既能避免丙烯酰胺的生成,又能显著提高川芎嗪的生成量和褐色度,因此低温蒸汽熏醅工艺更值得提倡推广。     

水分含量对即食酥脆鲫鱼质构及色泽的影响

采用两段式脱水烤制方式开发即食酥脆鲫鱼,以质构和色泽为指标,结合感官评定,探讨了烤前水分含量(70%降至45%)及最终水分含量(11%降至3%)对酥脆鲫鱼质构和色泽的影响。结果表明:随着烤前水分含量的降低,硬度、咀嚼性、剪切力增大,但从70%降至55%变化不显著,进一步降低之后显著增大(p<0.05),L*值减小,a*、b*值增大,从60%降至55%产品a*、b*值增加较显著(p<0.05);随着最终水分含量的降低,硬度、剪切力增大,咀嚼性先增大后略微减小,弹性、内聚性及回复性减小,3%~5%变化不明显,L*值增大,a*、b*值减小,5%~9%之间差别不显著(p>0.05)。结合感官评定确定烤前水分含量在55%,二次干燥之后最终水分含量为5%时产品品质最佳。      

Variety and storage conditions affect the precursor content and amount of acrylamide in potato crisps

BACKGROUND: Acrylamide, a probable human carcinogen, is formed from the amino acid asparagine and reducing sugars when potato products are processed at high temperatures. This is a two‐year study on five Swedish‐grown potato clones, two of which are adapted to cold storage. The clones represented a wide range of precursor concentrations: asparagine, 3.7–15.3 mg g^?1; reducing sugars, 0.9–14.9 mg g^?1. Crisps were prepared in laboratory‐scale equipment mimicking industrial processing conditions. RESULTS: Potatoes stored at 4 °C had significantly higher levels of glucose and fructose than potatoes stored at 8 °C. Acrylamide levels were significantly higher in crisps made from potatoes stored at 4 °C. Two clones with a large difference in asparagine concentration but similar glucose and fructose concentrations gave crisps with significantly different acrylamide contents. The lowest levels of acrylamide were found in crisps made from the potato variety with the lowest asparagine concentration. CONCLUSION: The findings show that variety and storage conditions influence the levels of precursors. Acrylamide formation in crisps can be reduced by using potato varieties with low levels of both asparagine and reducing sugars. Mass transport of precursors during heating is suggested to be important for acrylamide formation in potato crisps. Copyright © 2007 Society of Chemical Industry     

油炸马铃薯片中丙烯酰胺形成的影响因素的研究

丙烯酰胺是富含碳水化合物和氨基酸的食品经高温加热发生美拉德反应而产生的,但有关影响丙烯酰胺形成因素的研究却较少。探讨了油炸温度、原料中还原糖和氨基酸含量、鲜薯切片浸泡液的柠檬酸浓度、油炸前薯片的水分含量及抗氧化剂和油的使用时间对丙烯酰胺形成的影响。结果表明:原料中还原糖和氨基酸含量越高,产品中生成的丙烯酰胺就越多;油炸温度越高,产品中丙烯酰胺含量也相应越高;浸泡液柠檬酸浓度越大,产品中丙烯酰胺含量越低;而随着半成品中含水量的降低,产品中的丙烯酰胺含量也逐渐减少;在油中添加不同浓度的BHT和TBHQ以及采用使用时间不同的油,对加工出来的薯片之间丙烯酰胺含量没有显著的影响。     

面包加工工艺对其丙烯酰胺含量影响

面包在加工过程中会产生丙烯酰胺,对食品安全带来一定危害。该文研究了面包加工工艺对其丙烯酰胺含量影响,包括烘烤温度、烘烤时间、水分含量、发酵方法四方面。研究结果表明,烘烤温度、烘烤时间、面包水分含量及发酵方法对面包中丙烯酰胺含量具有一定影响,在保证面包品质的前提下,采用高温短时烘烤、降低面包坯水分含量、延长发酵时间有利于降低面包中丙烯酰胺含量。该论文研究对降低面包中丙烯酰胺含量具有理论和技术参考意义。     

几种食品添加剂对挤压即食食品丙烯酰胺形成的抑制效果研究

以马铃薯-小麦混合粉为原料,通过在挤压膨化即食食品中,添加不同种类、不同浓度的食品添加剂,研究不同添加剂对产品中丙烯酰胺含量的影响。结果表明:海藻糖、大豆多肽、茶多酚、竹叶提取物、氯化钙等食品添加剂的添加对挤压产品中丙烯酰胺含量的影响显著(p<0.05)。其中当氯化钙添加量达到0.5%时,产品中丙烯酰胺含量比对照减少了80%;大豆多肽添加量达到3%以上或竹叶提取物含量达到0.3%时,产物中丙烯酰胺含量对比对照组减少了50%。     

Influence of seed roasting process on the changes in composition and quality of sesame (Sesame indicum) oil

The composition and quality changes of sesame oils prepared at different roasting temperatures (180–260°C) from sesame seed were evaluated and compared with an unroasted oil sample. There were no apparent differences in characteristics, such as acid value, iodine value, saponification value and refractive index, of sesame oils prepared at a roasting temperature between 180 and 220°C. The colour units and total polar content of oils increased in relation to an increase in roasting temperature. The phospholipid content was reduced from 690 mg kg^?1 in unroasted oil to 0 mg kg^?1 in the oil prepared using a 260°C roasting temperature. The fatty acid content of the oil was reduced markedly, especially in oleic and linoleic acids, when the roasting temperature was over 220°C. The amounts of chlorophyll and sesamolin decreased with increasing roasting temperature. However, the highest level of sesamol and γ-tocopherol was found in oils prepared with a 200–220°C roasting temperature. The sesame oil prepared at a 200°C roasting temperature had the best flavour score when compared with the other samples.     

不同贮藏条件对冻干荔枝色泽的影响

以冷冻干燥后的怀枝荔枝干为研究对象,对不同贮藏条件下(光照、氧气、温度、湿度)冻干荔枝果肉的色泽变化进行了研究。结果表明,影响冻干荔枝色泽变化的主要因素为贮藏温度、表面湿度及氧气。密封贮藏的冻干荔枝在37℃下保存两周后,出现褐变及萎缩变形现象,而在有氧气(空气中)及相对湿度65%～70%的情况下,色泽变化更加明显。同样包装的冻干荔枝果肉在低温(4℃)及密封情况下,贮藏90d仍能较好地保持原有色泽基本不变,25℃贮藏两个月的冻干荔枝出现明显的变色现象。低温及干燥环境是保持冻干荔枝色泽的理想条件。     

Study of acrylamide in coffee using an improved liquid chromatography mass spectrometry method: Investigation of colour changes and acrylamide formation in coffee during roasting

An improved analytical method for the determination of acrylamide in coffee is described using liquid chromatography coupled to mass spectrometric detection (LC-MS). A variety of instant, ground and laboratory roasted coffee samples were analysed using this method. The sample preparation entails extraction of acrylamide with methanol, purification with Carrez I and II solutions, evaporation and solvent change to water, and clean-up with an Oasis HLB solid-phase extraction (SPE) cartridge. The chromatographic conditions allowed separation of acrylamide and the remaining matrix co-extractives with accurate and precise quantification of acrylamide during MS detection in SIM mode. Recoveries for the spiking levels of 50, 100, 250 and 500 µg/kg ranged between 99 and 100% with relative standard deviations of less than 2%. The effects of roasting on the formation of acrylamide and colour development were also investigated at 150, 200 and 225°C. Change in the CIE (Commission Internationale de l'Eclairage) a* colour value was found to show a good correlation with the change in acrylamide. CIE a* and acrylamide data was fitted to a non-linear logarithmic function for the estimation of acrylamide level in coffee. Measured acrylamide levels in commercial roasted coffees compared well with the predicted acrylamide levels from the CIE a* values.