An Assessment of Light-Induced Off-Flavors in Retail Milk

Samples of whole and skim milk from two local dairy plants that were packaged in 3.8-L plastic containers (nonreturnable high density polyethylene) and 1.9, .95, and .48-L fiberboard containers and displayed in the dairy cases of four local grocery stores under normal fluorescent light were analyzed for light-induced changes in flavor and riboflavin content. Milk samples were analyzed daily for flavor, odor, appearance, and riboflavin content. Sensory evaluation was by 25 untrained panelists, and riboflavin was determined by HPLC method. Milk samples were analyzed first in summer, then repeated in winter. Data indicated that under typical production and storage conditions in the area, type and size of container, fat content, and season of production had no major damaging effects on flavor, odor, appearance, or riboflavin content of retail milk.     

High Performance Liquid Chromatographic Analysis of Riboflavin (Vitamin B2) with Visible Absorbance Detection in Italian Cheeses

A high-performance liquid chromatographic method for riboflavin determination in cheese samples was developed. Reverse phase conditions were used, i.e., a C-18 column isocratically eluted with an acetonitrile water mixture (20:80). A shift of the detection wavelength from 267 to 446 nm was proposed as a simple and very effective means for circumventing the problem of incomplete resolution of riboflavin from interfacing peaks. The detection limit of riboflavin was 2.5 ng, a value well above the level required for determining the riboflavin content in cheese samples. From both high- and low-fat cheese, the riboflavin recovery was the same (90.2%). The riboflavin content of several different Italian cheeses was determined.     

BRNING TIME AND SMOKING INFLUENCE ON ACCEPTABILITY OF IDIAZABAL CHEESE

Brining time and traditional smoking effects on sensory characteristics (appearance, odor, texture, taste and aftertaste) during ripening of Idiazabal cheese were studied in terms of acceptability. The range of brining time (12, 24 and 36 h) considered in this study showed little effect on sensory parameters. In longer brined cheeses, an improvement of rind acceptability was observed especially at the beginning of the ripening period. In young products the texture of the more salted cheese was preferred, in hard cheeses consumers preferred the less salty ones. The traditional smoking process had a greater effect on sensory parameters perceived by consumers than brining time did. It was observed that smoking had a positive influence on acceptability of rind, paste color and eyes. Smoking also increased odor and texture acceptability.     

The influence of storage temperature and storage time on color stability,retail properties and case-life of retail-ready beef

Steaks from three different muscles were either vacuum or carbon dioxide packed and stored for up to 24 weeks at three different storage temperatures (−1.5, 2, or 5 °C). Following storage, they were displayed for up to 30 h. CIE color coordinates, the oxidative states of myoglobin and pH were measured and muscle color, surface discoloration, retail appearance, and odor were evaluated prior to storage and during display (0, 1, 2, 4, 6, 24 and 30 h), and/or immediately prior to and following display. Prior to display, pH was negatively related to duration of storage, and samples stored at −1.5 °C had the highest and samples stored at 5 °C, had the lowest pH. Perception of muscle color was influenced by duration of storage and display, but lower storage temperatures appeared to produce a stabilizing effect. Both lightness of muscle color and deoxymyoglobin content were apparently not influenced by storage temperature or duration of storage or display. Both oxymyoglobin (OMB) and redness, as defined by CIE a* values, were lost progressively during storage and display, but this loss was progressively lower as storage temperature decreased. Yellowness of muscle color, as defined by CIE b* values, generally decreased as storage was prolonged, and this decrease was observed more quickly at higher storage temperatures. Surprisingly, b* values were not related to duration of display. Both surface discoloration and metmyoglobin (MMB) content increased progressively during storage and display. Samples stored at 5 °C displayed the most surface discoloration, while samples stored at −1.5 °C contained the least MMB and displayed the least surface discoloration. Retail appearance deteriorated progressively during storage in all samples stored at 2 and 5 °C and in samples stored at −1.5 °C, which were displayed for at least 24 h. Retail appearance also deteriorated progressively during display in samples stored at −1.5 and 2 °C for three weeks or longer and in samples stored at 5 °C for 0 to 15 and 24 weeks. In unstored samples, samples to be stored at −1.5 °C generally received the lowest retail appearance scores, but after prolonged storage and display, samples stored at −1.5 °C received higher retail appearance scores than samples stored at 5 °C, particularly when samples were stored for 12 weeks or longer and displayed for 1 h or more. Odor deteriorated progressively during storage when measured both prior to display and after 30 h of display. In samples stored for three weeks or longer, samples stored at −1.5 °C generally received the lowest odor scores and were perceived to have the least prevalent off-odors. Samples stored at −1.5 °C maintained a retail case-life of 30 h, when stored for up to 17 weeks, while samples stored at 2 and 5 °C maintained a retail case-life of 30 h, when stored for only eight and seven weeks, respectively. Consequently, storage life can be more than doubled by storage at subzero temperatures (−1.5 °C).     

Effect of liquid whey protein concentrate–based edible coating enriched with cinnamon carbon dioxide extract on the quality and shelf life of Eastern European curd cheese

Fresh unripened curd cheese has long been a well-known Eastern European artisanal dairy product; however, due to possible cross-contamination from manual production steps, high moisture content (50–60%), and metabolic activity of present lactic acid bacteria, the shelf life of curd cheese is short (10–20 d). Therefore, the aim of this study was to improve the shelf life of Eastern European acid-curd cheese by applying an antimicrobial protein-based (5%, wt/wt) edible coating. The bioactive edible coating was produced from liquid whey protein concentrate (a cheese production byproduct) and fortified with 0.3% (wt/wt, solution basis) Chinese cinnamon bark (Cinnamomum cassia) CO₂ extract. The effect of coating on the cheese was evaluated within package-free (group 1) and additionally vacuum packaged (group 2) conditions to represent types of cheeses sold by small and big scale manufacturers. The cheese samples were examined over 31 d of storage for changes of microbiological (total bacterial count, lactic acid bacteria, yeasts and molds, coliforms, enterobacteria, Staphylococcus spp.), physicochemical (pH, lactic acid, protein, fat, moisture, color change, rheological, and sensory properties). The controlled experiment revealed that in group 1, applied coating affected appearance and color by preserving moisture and decreasing growth of yeasts and molds during prolonged package-free cheese storage. In group 2, coating did not affect moisture, color, or texture, but had a strong antimicrobial effect, decreasing the counts of yeasts and molds by 0.79 to 1.55 log cfu/g during 31 d of storage. In both groups, coating had no effect on pH, lactic acid, protein, and fat contents. Evaluated sensory properties (appearance, odor, taste, texture, and overall acceptability) of all samples were similar, indicating no effect of the coating on the flavor of curd cheese. The edible coating based on liquid whey protein concentrate with the incorporation of cinnamon extract was demonstrated to efficiently extend the shelf life of perishable fresh curd cheese, enhance its functional value, and contribute to a more sustainable production process.     

发酵酸鱼贮藏过程中理化与感官品质变化研究

本文以发酵成熟的酸鱼为研究对象,真空包装后在不同温度(4、25、35℃)条件下进行保藏试验,以感官评价、失水率、全质构、蛋白质组成、微观结构等为主要指标评价发酵酸鱼在不同贮藏条件下的品质变化与保藏特性。结果表明,保藏期90 d内,35℃贮藏加速产品感官品质劣变,失水较多,硬度变大,蛋白组成变化显著,蛋白质降解相对剧烈,肌肉纤维收缩严重,纤维间隙增大;室温(25℃)条件下贮藏期内产品感官品质较35℃相对稳定;与25和35℃条件下相比,冷藏(4℃)对发酵酸鱼的外观、气味、滋味和口感保持较好,低温有利于减缓酸鱼中水分流失、质构变化以及蛋白质的降解,90 d内能较好保持产品的感官品质和组织结构。     

Reducing SO(2) in fresh pork burgers by adding chitosan

The use of 0.02 or 0.05% chitosan is proposed to reduce from 450 to 150mgkg(-1) the SO(2) required to preserve pork burgers aerobically packed and stored at 2°C for up to 21days under retail display conditions. The effects of chitosan and/or sulfite addition and the storage time were determined in fresh (color deterioration, lipid oxidation, pH, total viable counts, Escherichia coli and coliforms, Salmonella, appearance and odor) and cooked (appearance, odor, flavor and texture) burgers. The addition of either 0.02 or 0.05% chitosan was not detected by sensory analysis, and extended the shelf life of low-SO(2) burgers from 7 to 14days. Chitosan enhanced the preservative effects of sulfite at a low dose, acting on the main causes of meat deterioration (bacterial spoilage, color stability and lipid oxidation), and provided good sensory properties to fresh and cooked pork burgers.     

Influence of Initial Riboflavin Content on Retention in Pasta During Photodegradation and Cooking

Samples of enriched pasta were stored under controlled lighting conditions and the loss of riboflavin was determined. After an initial rapid degradation, the riboflavin level continued to decrease slowly. After 12 wk, more than 80% the riboflavin had degraded. When pasta samples- with varied levels of riboflavin enrichment were exposed to light for 2 days, riboflavin losses ranged from 57.8–64.3%. Riboflavin leaching from pasta during cooking was also shown to be concentration independent with 34.5–37.6% of the riboflavin solubilized in the cooking water. Riboflavin in pasta which had been exposed to light for 2 days prior to cooking had a similar percentage of the undegraded riboflavin leached into the cooking water.     

瑞士奶酪生产工艺研究

以新鲜牛乳为主要原料,根据瑞士奶酪的生产工艺,采用L9(34)正交实验的方法,研究了不同切割尺寸、发酵剂添加比例、发酵剂添加量、发酵温度和切割pH对瑞士奶酪色泽、滋气味和组织状态的影响,确定了生产瑞士奶酪的最佳工艺条件为发酵剂添加量0.02%(质量分数),凝块切割尺寸0.6cm,切割pH6.60,发酵剂(唾液链球菌嗜热亚种∶瑞士乳杆菌∶谢氏丙酸杆菌)添加比例2∶2∶1,发酵温度37℃。     

Behavior of Listeria monocytogenes and Aeromonas spp. on fresh-cut produce packaged under equilibrium-modified atmosphere.

Storage experiments were conducted to follow the behavior of pathogens on fresh-cut vegetables (trimmed brussels sprouts, grated carrots, shredded iceberg lettuce, and shredded chicory endives) packaged under an equilibrium-modified atmosphere (EMA) (2 to 3% O2, 2 to 3% CO2, and 94 to 96% N2) and stored at 7 degrees C. As a comparison, fresh-cut vegetables were also packaged in a perforated high-barrier film (air conditions) and stored at 7 degrees C. In a first step, the shelf life of the vegetables in the two kinds of packages was determined by evaluating the microbiological quality as well as the sensorial quality (appearance, taste, and odor). In general, sensorial properties were faster in limiting the shelf life than microbiological criteria. The shelf life of the vegetables stored under an EMA was extended by 50% or more, compared with the air-stored vegetables. In a second storage experiment, the four fresh-cut vegetables were inoculated with a cocktail of psychrotrophic pathogens (Listeria monocytogenes, Aeromonas caviae [HG4]) and A. bestiarum (HG2) before packaging under an EMA and air at 7 degrees C. The inoculated pathogens were more influenced by the type of vegetable than by the type of atmosphere. No growth was detected on the brussels sprouts or on carrots (L. monocytogenes). Aeromonas spp. had a higher growth rate than L. monocytogenes on the shredded chicory endives and shredded iceberg lettuce at 7 degrees C.     

Comparative study of flavor, texture, and sensory in cream cheese and cholesterol-removed cream cheese

This study was performed to compare flavor, texture, and sensory profiles of cream cheese and cholesterolremoved cream cheese made from whole milk and cream. The cholesterol was removed by crosslinked β-cyclodextrin and the cheeses were stored at 7°C for 4 week. To quantify the flavor compounds, the cheeses (0, 1, 2, 3, and 4 week) were extracted by solid-phase microextraction, analyzed by GC-MS and quantified by GC-flame ionization detector (FID). Tentatively identified flavor compounds were 11 acids, 2 ketones, 1 amine, 1 alcohol, 2 lactone, and 1 alkene. In texture profile analysis such as hardness, cohesiveness, adhesiveness, and sensory analysis such as appearance, flavor, taste, and texture properties were not significantly different (p>0.05) between two cheeses. On the basis of our results, it is concluded that no adverse changes was shown in the cholesterol-removed cream cheese in flavor, texture, and sensory characteristics during 4-week storage.     

湖北烟区烤烟质量综合评价及典型相关分析

对湖北烤烟外观质量、化学成分和感官质量状况进行分析,并与津巴布韦烤烟进行比较,结果表明:1)湖北烤烟颜色柠檬黄-橘黄,结构疏松,身份适中;香气质好量足,杂气较轻,余味较舒适,配伍性强.与津巴布韦烤烟相比较,外观及感官质量仍有一定差距:在颜色、成熟度和刺激性上的差异达到0.05显著水平;在结构、香气质、香气量、杂气和余味上的差异达到0.01显著水平;化学成分含量及其比值与津巴布韦烤烟差别不大.2)烤烟外观质量与感官质量关系密切,两者间的典型相关主要是由外观质量中的颜色、成熟度、结构、身份、油分和色度及感官质量中的香气质、香气量和杂气相关决定的.化学成分与感官质量的典型相关主要是由化学成分中的烟碱、总氮、糖碱比和氮碱比与感官质量中的香气质、刺激性和余味相关决定的.     

COTTAGE CHEESE SHELF LIFE AND SPECIAL GAS ATMOSPHERES

SUMMARY– Cottage cheese samples were stored at 3–4°C for 10–12 days in special all-glass containers with purified carbon dioxide, nitrogen and air atmospheres. Shelf-life quality of the cheese was measured by taste panel scoring and by bacterial counts of the top centimeter of product. Carbon dioxide slightly decreased the bacterial counts but it produced an acid or tart cheese. Nitrogen did not significantly decrease the bacterial counts nor affect the taste of the cheese.     

Calcium Supplementation of Cottage Cheese

Cottage cheese (100 g) provides only 6% of the calcium Recommended Daily Allowance for adults. Samples of fresh cheese were supplemented with calcium salts (chloride, lactate, or phosphate monobasic) to double the calcium content of the cheese to approximately 145 mg/100 g, and the effects of the supplementation on taste and microbial stability were studied. Supplementations did not affect pH or microbial stability during 21 d of refrigerated storage. Sensory evaluation results of a 12-member taste panel showed higher flavor and preference scores for control than for all supplemented samples (P<.05) but no difference in odor, color, or texture. Overall, chloride appeared to be preferable for calcium content supplementation because only .26% (wt/wt) of the salt was required to obtain the desired calcium content level and the mineral was evenly distributed in the cheese.     

Effect of starter cultures on the physico‐chemical and biochemical features in ewe cheese made with extracts from flowers of Cynara cardunculus L

The effect of starter cultures on the physico‐chemical and biochemical features of Los Pedroches cheese made by using Cynara Cardunculus L extracts as vegetable coagulant was assessed. Specimens of cheese containing no starter (vats A and C) and others to which a lactic acid starter was added (vats B and D) were stored either under typical farmhouse ripening conditions (vats A and B) or in a controlled chamber at 14°C and 80% relative humidity (vats C and D) for 90 days. The addition of starter cultures and the ripening conditions where found to have no appreciable effect on the moisture, fat, protein, ash, NaCl, Ca and P contents of the cheese, nor on its water activity; however, it resulted in increased lactic acid contents and lower pH values relative to control specimens throughout ripening. The protein breakdown of the cheeses was assessed in terms of soluble nitrogen, non‐protein nitrogen, aminoacid nitrogen, ammonia nitrogen, soluble tyrosine and tryptophan, and urea‐PAGE. Proteolysis was generally more marked and rapid in cheese containing the lactic starter, the NPN, NH₃ ‐N and soluble Tyr and Trp contents of which were significantly higher than those of the cheese obtained with no starter. The PAGE technique revealed no appreciable differences between the four cheese batches studied; however, it showed the cheese to be more resistant to β‐CN hydrolysis than to α_s‐CN hydrolysis. In general, the flavour and aroma scores were higher in batches obtained with starter cultures and ripened under controlled conditions. © 1999 Society of Chemical Industry     

Monitoring Chemical and Microbial Changes of Cottage Cheese using a Full-history Time-temperature Indicator

Cottage cheese (4% milkfat) was stored under three isothermal conditions (3, 9, and 15°C) and one varied temperature condition for the length of its useful shelf life–up to 32 days. Attached to each one-half pint carton were two full history, enzymatic based, time-temperature indicators (I-POINT models #4014 and #4021). Throughout the study quality attributes of the cottage cheese, as determined by chemical and microbial means, and the indicator progress were periodically monitored. The cheese spoiled due to growth of acid-forming bacteria under the warmer conditions and due to psychrotrophic bacteria under the coldest condition. Response of the I-POINT model 4014 was significantly related to changes in three of the quality attributes of the cottage cheese, specifically: pH, standard plate count when the cheese was stored at 8.8° C, and titratable acidity when the cheese was stored at 15.1° C.     

The effect of three different ripening/storage conditions on the distribution of selected parameters in individual parts of Dutch‐type cheese

The aim of the study was (i) to detect changes of dry matter, NaCl and twenty‐two free amino acids contents, pH and levels of selected microorganisms in four layers of cheese (from edge to core) during ripening and storage period and (ii) to describe the changes of the above‐mentioned parameters caused by early relocation of cheese from optimum ripening conditions to refrigeration temperatures. The number of mesophilic aerobic and facultative anaerobic bacteria and lactic acid bacteria differed significantly (P < 0.05) during the experiment dependent on the analysed layer and ripening/storage conditions. The free amino acid content differed significantly in individual analysed layers of cheese and also according to individual ripening/storage conditions. The highest content of free amino acids was found in samples stored at optimal ripening temperatures. Cheese hardness was also analysed and the lowest one was detected in samples ripened under optimal temperatures for the whole period. Early release of cheeses into storage rooms with lower temperature significantly affected properties of these products.     

Active packaging of cheese with allyl isothiocyanate, an alternative to modified atmosphere packaging

The natural antimicrobial compound allyl isothiocyanate (AITC), found in mustard oil, is effective against cheese-related fungi both on laboratory media and cheese. Penicillium commune, Penicillium roqueforti, and Aspergillus flavus were more sensitive to AITC when it was added just after the spores had completed 100% germination and branching had started on Czapek yeast extract agar than were spores in the dormant phase. The use of 1 AITC label (Wasaouro interior labels, LD30D, 20 by 20 mm) in combination with atmospheric air in the packaging extended the shelf life of Danish Danbo cheese from 4 1/2 to 13 weeks. Two AITC labels extended the shelf life from 4 1/2 to 28 weeks. Both 1 and 2 labels in combination with modified atmosphere packaging extended the shelf life of the cheese from 18 to 28 weeks. This study showed that AITC was absorbed in the cheese, but it was not possible to detect any volatile breakdown products from AITC in the cheese. Cheese stored for up to 12 weeks with an AITC label had an unacceptable mustard flavor. The mustard flavor decreased to an acceptable level between weeks 12 and 28. Cheese stored in atmospheric air had a fresher taste without a CO2 off-flavor than did cheese stored in modified atmosphere packaging. AITC may be a good alternative to modified atmosphere packaging for cheese. The extended shelf life of cheese in the package is very desirable: the cheese can be transported longer distances, and the packaging can be used for the final maturing of the cheese. Furthermore, AITC can address problems such as pinholes and leaking seals in cheese packaging.