The effect of some manufacturing conditions on the development of flavour in Cheddar cheese

Organoleptic assessments by the NIRD panel of Cheddar cheeses made with Streptococcus cremoris NCDO 924 or 1986, either in enclosed vats excluding nonstarter flora or in open vats, showed that high viable starter populations in curd did not give stronger-flavoured cheese, but led to the development of bitterness. Cheeses made in open vats developed typical flavour more rapidly than those made in enclosed vats. Maturation temperature was the most important factor in determining the flavour intensity; cheese ripened at 13d?C for six months had stronger flavour than corresponding ones ripened at 6d?C for nine months, irrespective of the starter or vat used.     

Elimination of the development of bitter flavour in Cheddar cheese made from milk containing heat-denatured whey protein

A method has been developed for increasing the yield of Cheddar cheese by as much as 7.5% by the incorporation of denatured whey protein in curd. The process effectively eliminates the development of intense bitter off-flavours which are generally associated with the production of cheese from acidified milk. Although the manufacturing procedure produces cheese with acceptable Cheddar flavour, the development of high quality Cheddar flavour is impaired     

Comparison of different bacterial culture systems for the production of reduced-fat Cheddar cheese

Six different culture systems, two controls (A and B) containing mesophilic starter lactococci and four experimental systems (C, D, E and F) containing mesophilic lactococci plus adjunct cultures (all of which contained Lactobacillus helveticus ), were compared for their effects on the quality of reduced-fat Cheddar cheese (175 g/kg fat). Adjunct cultures (i.e. C, D and F) resulted in cheeses having significantly higher concentrations of low molecular mass peptides (i.e. < 0.5 kDa) and free amino acids than the control cheeses. The adjunct cultures D and F resulted in cheeses that received higher flavour scores and were more acceptable than the control cheeses at 90 and 180 days.     

Mineral composition of lamb carcasses from the United States and New Zealand

The mineral composition-iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), fluoride (F), and phosphorus (P) (New Zealand lamb only)-of lean tissue from lamb retail cuts was studied. Twenty-four US lamb carcasses of different ages (5 to 11 months), geographical regions (Texas, Colorado and Montana) and USDA quality grades (Prime and Choice) and 27 New Zealand lamb carcasses from three weight groups (11 to 12·5 kg, 13 to 14·5 kg, and 16·5 to 18 kg), age rangining from 7 to 8 months, were selected for use in this study. Mineral concentrations were influenced more by retail cut and age than by quality grade or weigth group. Foreshank and shoulder cuts from both the US and New Zealand group consistently had the highest (P < 0·05) Zn content among the cuts. The K content of the muscle in US lambs increased as age increased, while the level of Ca and Zn in New Zealand lambs decreased as carcass weight increased. Except for Ca, the mineral concentrations of the lean tissue from US lambs were higher than the New Zealand lambs, although the differences were not always significant. US lambs had approximately 20%, 30% and 37% more Fe, Zn and Mg, respectively, but 27% less Ca than lean tissue from the New Zealand lambs.     

Comparison of performance and quantitative descriptive analysis sensory profiling and its relationship to consumer liking between the artisanal cheese producers panel and the descriptive trained panel

The aim of this research was to compare the performance and sensory profiling of a panel of artisanal cheese producers against a trained panel and their relationship to consumer liking (external preference mapping). Performance was analyzed statistically at an individual level using the Fisher's test (F) for discrimination, the mean square error for repeatability, and Manhattan plots for visualizing the intra-panel homogeneity. At group level, performance was evaluated using ANOVA. External preference mapping technique was applied to determine the efficiency of each sensory profile. Results showed that the producers panel was discriminant and repetitive with a performance similar to that of the trained panel. Manhattan plots showed that the performance of artisanal cheese producers was more homogeneous than trained panelists. The correlation between sensory profiles (Rv = 0.95) demonstrated similarities in the generation and use of sensory profiles. The external preference maps generated individually with the profiles of each panel were also similar. Recruiting individuals familiar with the production of artisanal cheeses as panelists is a viable strategy for sensory characterization of artisanal cheeses within their context of origin because their results were similar to those from the trained panel and can be correlated with consumer liking data.     

Influence of ripening temperature on the volatiles profile and flavour of Cheddar cheese made from raw or pasteurised milk

Cheddar cheeses were made from raw (R1, R8) or pasteurised (P1, P8) milk and ripened at 1°C (P1, R1) or 8°C (P8, R8). Volatile compounds were extracted from 6 month-old cheeses and analysed, identified and quantified by gas chromatography-mass-spectrometry. A detailed sensory analysis of the cheeses was performed after 4 and 6 months of ripening. The R8 cheeses had the highest and P1 the lowest concentrations of most of the volatile compounds quantified (fatty acids, ketones, aldehydes, esters, alcohols, lactones and methional). The R8 and P8 cheeses contained higher levels of most of the volatiles than R1 and P1 cheeses. Ripening temperature and type of milk influenced most of the flavour and aroma attributes. Principal component analysis (PCA) of aroma and flavour attributes showed that P1 and R1 had similar aroma and flavour profiles, while R8 had the highest aroma and flavour intensities, highest acid aroma and sour flavour. The age of cheeses influenced the perception of creamy/milky and pungent aromas. PCA of the texture attributes separated cheeses on the basis of ripening temperature. The R8 and P8 cheeses received significantly higher scores for perceived maturity than P1 and R1 cheeses. The P1 and R1 cheeses had similar values for perceived maturity. In a related study, it was found that concentrations of amino acids and fatty acids were similar in R1 and P1 during most of the ripening period, and R1 and P1 cheeses had low numbers of non-starter lactic acid bacteria (NSLAB). The panel found that ripening temperature, type of milk and age of cheeses did not influence the acceptability of cheese. It is concluded that NSLAB contribute to the formation of volatile compounds and affect the aroma and flavour profiles and the perceived maturity of Cheddar cheese.     

我国食品安全国家标准与美国食品法规制定程序对比及分析

食品安全国家标准的制定程序是确保标准内容权威公正、科学合理的重要保障,也在一定程度上影响标准的正确认识、理解和执行。本研究对我国食品安全国家标准和美国食品法规的制定程序和特点进行梳理、对比和分析,探讨两者存在的差异及原因,为我国食品安全国家标准的管理提供新的思路和建议。     

Sodium content in retail Cheddar, Mozzarella, and process cheeses varies considerably in the United States

Reducing the sodium content in cheese is expected to contribute to reducing the overall intake of sodium by US consumers. The purpose of this study was to measure the sodium levels in cheeses that are most commonly purchased by US consumers in the retail market, including brand and private label. A secondary purpose of the study was to generate data that can enable the dairy industry to adopt best practices regarding sodium levels in cheeses. The sodium content of a total of 1,665 samples of Cheddar (650 samples), low moisture part skim (LMPS) Mozzarella (746 samples), and process cheese singles (269 samples) from 4 geographical regions were collected over a period of 3 wk, and were analyzed over a 1-mo period. Process cheese contained the highest mean level of sodium (1,242 mg/100 g), followed by string cheese (724 mg/100 g). Across Cheddar cheese forms and brands, the mean analytical sodium was 615 mg/100 g, with 95% between 474 and 731 mg/100 g; label sodium ranged from 600 to 800 mg/100 g (mean 648 mg). Across all LMPS Mozzarella forms and brands, the mean analytical sodium was 666 mg/100 g, with 95% between 452 and 876 mg/100g; label sodium ranged from 526 to 893 mg/100 g (mean 685 mg). Across all process cheese forms and brands, the mean analytical sodium was 1,242 mg/100 g, with 95% between 936 and 1,590 mg/100 g; label sodium ranged from 1,185 to 1,740 mg/100 g (mean 1,313 mg/100 g). These findings demonstrate that manufacturers tended to be conservative with their reporting of sodium on labels. Manufacturers need to reduce variability to better target desired sodium levels, which is an opportunity for better process control, and will enable them to label sodium more accurately.     

Optimized dairy grazing systems in the northeast United States and New Zealand. II. System analysis.

Factors that optimize milk production from Northeast United States and New Zealand grazing systems are compared using a linear programming model. The objective function maximized gross margin per hectare of land farmed. The experimental design compared the optimum characteristics of each system over a range of milk prices. The Northeast has a shorter grazing season and lower cropping costs than New Zealand. The optimum pasture area was 49% of the farm for Northeast systems. Gross margins declined rapidly above 55% or below 36% pasture area. The optimum stocking rate was 1.13 cows/ha, or 2.3 cows/ha of pasture. Optimum per cow production was higher for Northeast [7105 kg of fat-corrected milk (FCM)] than New Zealand (5710 kg of FCM) systems. This was related to lower grain relative to milk prices in the Northeast. New Zealand, all-pasture systems gave the lowest cost per unit of milk but also gave the lowest gross margin across all milk price scenarios. The best use of purchased feed in New Zealand systems was to support increased stocking rate rather than per cow production. Optimum grazing management practices were similar for supplemented New Zealand and Northeast systems. All-pasture New Zealand systems are characterized by short lactations and long autumn rotations to transfer pasture in situ for winter feeding. Higher costs per unit of milk produced will be an inevitable consequence of maximizing gross margin at high milk prices in New Zealand systems.     

Effects of pectic fat mimetics and transglutaminase on the regularity of protein and fat degradation and flavour compounds in Cheddar cheese during ripening

The effect of simultaneous transglutaminase (TGase) treatment with pectic fat mimetics (PFM) addition on regularity of protein and fat degradation and flavour compound variations in Cheddar cheese during ripening was investigated. In the early stages of fermentation, the cheese with 20% PFM and 15 U/L TGase had a higher amino acid content. In the middle stage of fermentation, cheese with high concentration of TGase hydrolysed more proteins. Cheese supplemented with PFM and TGase showed increased content of long-chain polyunsaturated fatty acids, especially linoleic acid (C18:2). In addition, PFM and TGase compensated the flavour deficiencies of low-fat cheeses and had positive effects on volatile compounds such as alcohols, acids and methyl ketones. Overall, the characteristics and flavours of Cheddar cheese with the addition of PFM and TGase were superior to the control group, which could provide a theoretical basis for the application of PFM and TGase in cheese production.     

The effect of age on Cheddar cheese melting,rheology and structure,and on the stability of feed for cheese powder manufacture

Age-related changes to the rheology and structure of Cheddar for cheese powder manufacture, and how this influences the stability of cheese feed during pre-spray-drying storage, were investigated. Cheddar cheese (3, 5, 7, 9, 12 and 15 months old) was analysed for meltability by the Schreiber Test and small angle oscillation measurements. Results showed increasing stiffness and reduced activation energy for initiation of milk fat melting with age. Cheese feeds for manufacture of cheese powder were made, with or without emulsifying salts (ES), and analysed for emulsion stability. In the absence of ES, feeds made from 3 month old Cheddar were significantly more stable than those made from 5 month old cheese. A similar significant increase in emulsion stability was observed for cheeses of 7 months of age compared with 12 months, indicating the necessity to use Cheddar cheese aged 3 months or less to produce stable cheese feeds without ES.     

Dissimilarity scaling and INDSCAL analysis in the study of flavour differences between normal pHu and DFD beef

Overall dissimilarity measurement of paired stimuli followed by Individual Differences Scaling (INDSCAL) analysis was used to study flavour perception in a set of beef extracts. The experiment was designed to determine whether pH contributed to flavour difference between beef of “normal” ultimate pH (pHu5.8) and “dark-cutting” (DFD) beef (pHu6.2). Assessors distinguished the flavour of “normal” pHu and DFD beef both by a combination of pH and titratable acidity, and a second dimension independent of pH. The chemicals added to adjust pH independently of the original muscle composition contributed a third flavour dimension. Substantial assessor variation was observed in the relative weight given to the three flavour dimensions, and this is discussed in relation to the task of judging overall dissimilarity.     

Effect of curd washing on cheese proteolysis,texture, volatile compounds,and sensory grading in full fat Cheddar cheese

Curd was washed to varying degrees during Cheddar cheese manufacture, by partial replacement of whey with water at the early stages of cooking, to give target levels of lactose plus lactic acid in cheese moisture of 5.3 (control), 4.5, 4.3 and 3.9% (w/w). The cheeses were matured at 8 °C for 270 days. While curd washing had little effect on composition or the mean levels of proteolysis (as measured by pH 4.6 soluble nitrogen and levels of free amino acids), it led to cheeses that were, overall, firmer and less brittle. Curd washing resulted in cheeses having lower levels of some volatile compounds, and being less acid, more buttery, sweeter, saltier and creamier than non-washed cheeses that had more 'sweaty', pungent and farmyard-like sensory notes. The results suggest that curd washing during Cheddar manufacture may be used as a means of creating variants with distinctive flavour profiles.     

美国的食物过敏原标签管理走向

食物过敏是一种至今除了严防接触外尚无有效预防方法的免疫症状。在美国,食物过敏的敏感人群达总人口的4%。美国的食物过敏症90%以上由花生、坚果类、鱼类、甲壳类、乳类、小麦、大豆和蛋类引起。这八种过敏原合称“八大类”,是食品过敏原标记的重点。在过去10年内,美国因过敏原未标明造成的食品召回事件节节上升。本文回顾了美国FDA对食品过敏原标识管理所作的努力和美国食品过敏原标识的现状,简单介绍了去年通过的食品过敏原标签和消费者保护法,以及该法对食品酶制剂标签可能产生的影响。