Changes in selected biochemical and sensory parameters as affected by the superficial inoculation of Penicillium camemberti on dry fermented sausages

An atoxigenic strain of Penicillium camemberti was superficially inoculated on fermented sausages in an attempt to improve their sensory properties. The growth of this mould on the surface of the sausages resulted in an intense proteolysis and lipolysis, which caused an increase in the concentration of free amino acids, free fatty acids (FFA) and volatile compounds. Many of these were derived from amino acid catabolism and were responsible for the "ripened flavour", i.e. branched aldehydes and the corresponding alcohols, acids and esters. The development of the fungal mycelia on the surface of the sausages also protected lipids from oxidation, resulting in both lower 2-thiobarbituric acid (TBARS) values and lipid oxidation-derived compounds, such as aliphatic aldehydes and alcohols. The sensory analysis of superficially inoculated sausages showed clear improvements in odour and flavour and, as a consequence, in the overall quality of the sausages. Therefore, this strain is proposed as a potential starter culture for dry fermented sausage production.     

Effects of addition of anka rice on the qualities of low-nitrite Chinese sausages

Anka rice (AR), previously inoculated with Monascus purpureus, was added during manufacturing of low-nitrite Chinese sausages. Chemical compositions and water activities of sausages were not affected. “L”, “a”, and “b” values of sausages with less nitrite (25 ppm) and 0.5% AR added were not significantly different from those with more nitrite (100 ppm) added. Colours of the sausages without AR were light red whereas those with AR added were darker red. Addition of AR did not inhibit lipid oxidation. Higher VBN (volatile basic nitrogen) values of the samples with AR added were observed. With addition of AR, the nitrite degrading rate was retarded. Microbial counts of the sausages with AR added were significantly higher than those of the controls (100 ppm nitrite). The low-nitrite Chinese sausage with addition up to 1.5% AR was acceptable when stored at 4 °C for 28 days.     

Moulds and ochratoxin A on surfaces of artisanal and industrial dry sausages

The use of moulds as a seasoning for sausage can have both desirable and undesirable consequences. The desirable consequences are the creation of a successful product that appeals to consumers. The undesirable consequences are due to the growth of undesirable moulds that produce highly toxic secondary metabolites referred to as mycotoxins. The aim of the paper was to investigate the presence of moulds producing ochratoxin A (OTA) on the surface of sausages from northern Italy. A total of 757 mould strains were isolated from sausage casings. The most frequently identified species were Penicillium nalgiovense, Penicillium oxalicum, Eurotium amstelodami, Penicillium olsonii, Penicillium chrysogenum, Penicillium verrucosum, Penicillium viridicatum, and Eupenicillium crustaceum. Aspergillus ochraceus was detected in only one production lot. Approximately 45% of these samples were positive for the presence of OTA. On the casings of the investigated sausages, the lowest and highest OTA values were 3 and 18 μg/kg, respectively. The OTA concentration was reduced to below the limit of detection (LOD) by brushing and washing the sausages prior to sale. From these data it appears that the presence of OTA on the surface of sausage (on the casings) is not indicative of any health risk for human consumption of sausage, since OTA was not identified inside the dry meat.     

A fermented meat model system for studies of microbial aroma formation

A fermented meat model system was developed, by which microbial formation of volatiles could be examined. The model was evaluated against dry, fermented sausages with respect to microbial growth, pH and volatile profiles. Fast and slowly acidified sausages and models were produced using the starter cultures Pediococcus pentosaceus and Staphylococcus xylosus. Volatiles were collected and analysed by dynamic headspace sampling and GC-MS. The analysis was primarily focused on volatiles arising from amino acid degradation and a total of 24 compounds, of which 19 were quantified, were used for multivariate data analysis. Growth of lactic acid bacteria was comparable for model and sausages, whereas survival of S. xylosus was better in the model. Multivariate analysis of volatiles showed that differences between fast and slowly acidified samples were identical for model and sausage. For both sausage and model, fast-acidified samples had a high content of ketones, sulphides and methyl-branched acids, whereas slowly acidified samples had the highest content of methyl-branched alcohols, aldehydes, their ethyl esters, phenylacetaldehyde and methional. Furthermore, model repeatability with respect to pH, microbial growth and volatile profiles was similar to sausage production. Based on these findings, the model system was considered valid for studies of aroma formation of meat cultures for fermented sausage.     

Contribution of enterococci to the volatile profile of slightly-fermented sausages

The volatile profiles of slightly-fermented sausages inoculated with eight different enterococci strains were determined and compared with a fermented sausage manufactured without any inoculation. The volatile profile was determined by solid-phase microextraction (SPME) and gas chromatography coupled to mass spectrometry (GC/MS). A total of 121 volatile and semi-volatile compounds were identified in the samples of the final products (day 21). Terpenes from spices added during manufacture of dry-fermented sausages were the main group of compounds in the volatile profile. Other groups included alcohols (18% of total volatile compounds), aldehydes (16%), alkanes and alkenes (12%), and ketones (10%). These are derived from lipids, proteins or carbohydrates and formed during fermentation and ripening. In terms of global volatile composition, the batches inoculated with enterococci strains were similar to those obtained for non-inoculated batch. However, some quantitative differences in the volatile profiles of different batches were found, mainly in the compounds formed from amino acid catabolism (i.e.: propanol, isoamyl), from free fatty acid oxidation (i.e.: hexanal, hexanol), or from carbohydrate fermentation (i.e.: 2-butanone, acetoin). In comparison with non-inoculated sausages, some batches were more resistant to oxidation; they contained fewer volatile compounds arising from lipid oxidation. The use of different selected enterococci strains did not alter the volatile profile of slightly-fermented sausages. The enterococci strains provide similar volatile compounds to those usually reported in the literature.     

Effect of selected mould strains on lipolysis in dry fermented sausages

 Several batches of fermented sausages were prepared and inoculated with five strains of moulds belonging to the genera Penicillium and Mucor, selected for their enzymatic activity, and a strain of Penicillium nalgiovense obtained as a commercial starter culture. Control batches were manufactured similary, but without inoculation. Sausages were produced with either artificial or natural casings, and very similar results were obtained with both. The evolution of the different lipidic fractions was monitored, paying special attention to the free fatty acid (FFA) fraction. Two strains presented a high lipolytic activity as indicated by the rise in FFA in comparison to control batches. In conclusion, not all the mould strains contributed to the lipolytic process occurring during sausage ripening and, therefore, not all of these had a positive effect on the final quality of the product. If moulds are to be used for this purpose it is, therefore, necessary to carefully select suitable moulds beforehand. Received: 25 September 1998 / Revised version: 4 February 1999     

The contribution of Penicillium aurantiogriseum to the volatile composition and sensory quality of dry fermented sausages

An atoxygenic, proteolytic and lipolytic strain of Penicillium aurantiogriseum was tested for its ability to accelerate the production of volatile compounds and to improve the sensory properties of dry fermented sausages. The following batches of sausages were prepared: control; superficially inoculated with a spore suspension; added with an intracellular cell free extract; and superficially inoculated and added with the intracellular cell free extract. Higher levels of lipid oxidation products were found in the aroma extracts of sausages without a mould cover. In contrast, branched aldehydes and alcohols presented higher concentrations in superficially inoculated and extract added sausages, while esters only showed higher concentration in the first ones. The sensory analysis showed that sausages prepared with both treatments received the highest scores in all the properties evaluated, which demonstrated both the potential of this mould as producer of volatile compounds and the effectiveness of combining both treatments.     

辐照对猪肉火腿肠风味与品质的影响

分别以1、3、5、7、9 kGy剂量辐照处理火腿肠,然后对其辐照异味强度、脂质氧化、挥发性风味化合物、色差等指标进行检测,分析辐照对火腿肠风味及颜色品质的影响。结果发现,辐照处理可以显著促进火腿肠中脂质的氧化(P0.05),使得红度值(a~*)相比对照组显著降低(P0.05),但是对亮度值(L~*)和黄度值(b~*)影响不显著(P0.05)。随着辐照剂量加大,火腿肠的辐照异味明显增强,1~5 kGy范围内辐照异味不明显,当辐照剂量增加到7 k Gy时,火腿肠产生明显的令消费者不能接受的辐照异味。挥发性含硫化合物、2-丁烯、戊烷、1-戊烯、辛烷、己烷以及醛类化合物含量与对照组相比显著增多(P0.05),且与辐照剂量呈正相关。二硫化碳、二甲基二硫醚、2-甲基丙醛、3-甲基丁醛、己醛、丁烯和二甲苯是火腿肠辐照后产生的最主要挥发性化合物。结果表明,火腿肠经辐照处理后风味和色泽会发生劣变,特别是5 kGy以上的辐照剂量,并且这些品质变化与火腿肠中脂质的氧化密切相关。     

Effect of the packaging method and the storage time on lipid oxidation and colour stability on dry fermented sausage salchichón manufactured with raw material with a high level of mono and polyunsaturated fatty acids

The effects of fatty acid composition, two packaging methods (vacuum and 20% CO₂/80% N₂) and storage under refrigeration for 210 days were evaluated on a dry fermented sausage (salchichón), manufactured with raw material enriched in monounsaturated or polyunsaturated fatty acids. Fatty acid composition was determined on sausage mixtures and on ripened sausages and lipid oxidation and colour stability was determined on ripened sausage at different times during storage. The modification of fatty acid composition of the sausages raised the nutritional quality, slightly affecting the colour properties. Dry fermented sausages enriched in polyunsaturated and monounsaturated fatty acids presented higher lipid oxidation values than the control ones. Both packaging methods (vacuum and 20% CO₂/80% N₂) during 210 days of chilled storage had minor effects on the colour and the lipid oxidation stability.     

Addition of α-ketoglutarate enhances formation of volatiles by Staphylococcus carnosus during sausage fermentation

The effect of leucine and α-ketoglutarate addition on transamination of branched-chain amino acids was studied in model minces inoculated with Pediococcus pentosaceus and Staphylococcus carnosus. Leucine addition changed the ratio of volatile breakdown products of leucine, isoleucine and valine but not the total amount of the volatiles and it was concluded that the amount of free amino acids does not limit transamination of amino acids. The addition of α-ketoglutarate resulted in increased levels of methyl-branched aldehydes and insignificant positive changes in methyl-branched acid production. The results were verified in real fermented sausages with no, low (0.09% w/w) and high (0.36% w/w) addition of added α-ketoglutarate since the levels of the flavour intensive methyl-branched aldehydes and acids were drastically increased in sausages added α-ketoglutarate. The catabolism of phenylalanine was also induced by α-ketoglutarate and there were further indications of increased transamination of aspartate. A triangular test showed that the flavour of sausages with no and low addition of α-ketoglutarate could be clearly distinguished from one another. Altogether the results presented in this paper point to glutamate dehydrogenase, the enzyme catalyzing regeneration of α-ketoglutarate, as a key enzyme in catabolism of amino acids and thereby also in aroma formation during sausage processing.     

脂肪含量和包装方式对法兰克福香肠贮藏品质的影响

以法兰克福香肠为研究对象,以脂质氧化、色泽、质构和挥发性产物为评价指标,研究不同脂肪含量和包装方式对产品贮藏品质的影响。结果表明:随着贮藏时间延长,法兰克福香肠的硫代巴比妥酸值(TBARS)值和亮度均与脂肪含量呈正相关,与包装方式无关;香肠的红度与脂肪含量相关性不显著,与包装方式呈正相关;香肠的硬度和黏性与脂肪含量呈负相关,与包装方式相关性甚小;脂肪含量和包装方式与挥发性产物之间的相关性都较显著。选择较低脂肪含量和真空包装方式有利于保持法兰克福香肠的贮藏品质。     

模仿葡萄球菌接种对发酵香肠品质及氧化稳定性的影响

以模仿葡萄球菌(SStaphylococcus simulans)NJ201接种发酵香肠为实验组,自然发酵香肠为对照组,测定香肠的pH值、色差、质构、过氧化值(peroxide value,POV)、硫代巴比妥酸反应物(thiobarbituric reactive substances,TBARS)值、羰基含量、总巯...     

Application of soymilk skin as sausage wrapping for improving lipid oxidation

Yuba, the soymilk skin, was developed as edible films for sausage. Yuba (Y) were prepared with added pine-needle extract (YP) and employed to wrap sausage. Physical and mechanical properties and lipid oxidation of sausages were compared to sausages made with commercial collagen casing (C). Y films showed better transparency, oxygen-barrier properties, and UV-light barrier properties than C films (p < .05). Particularly, the addition of pine-needle extract increased DPPH activities from 31 to 48% and total phenol content from 7.52 to 14.64 mg gallic acid/g. Regarding application for sausage wrapping, Y (2.35%) and YP (2.66%) wrapped sausages with better protection against water loss during cooking compared to sausages made from C (5.84%). Especially, YP (3.57 MDA mg/kg) showed better protection against lipid oxidation for sausages than Y (4 MDA mg/kg) and C (4.62 MDA mg/kg) on day 6 after refrigerated storage. Yuba films could be employed as potential alternatives to gelatin films for manufacturing sausages.     

食盐添加量对哈尔滨风干肠脂质和蛋白氧化及挥发性化合物形成的影响

研究不同食盐添加量(2.5%、2.0%、1.5%、1.0%)对哈尔滨风干肠在发酵过程中脂质及蛋白氧化的影响。结果表明,降低食盐添加量可显著降低风干肠过氧化物值以及肌原纤维蛋白和肌浆蛋白的羰基含量和表面疏水性,增加总巯基含量(P<0.05),说明NaCl对风干肠的脂质和蛋白氧化有促进作用。此外,挥发性化合物分析结果表明,各组风干肠中挥发性化合物的含量随着发酵时间的延长逐渐增加,且食盐添加量对多数化合物的生成具有显著影响(P<0.05)。随着食盐添加量的降低,醛类物质总体水平下降,酮类、酸类、酯类和醇类物质的总体水平上升。与对照组(2.5%)相比,添加2.0%食盐的样品减少了因脂质和蛋白氧化生成的醛、醇、酸类等物质,增加了微生物代谢产生的酮、醇、酸、酯类等物质,改善了风干肠的整体风味。     

Effect of reuterin,produced by Lactobacillus reuteri on the surface of sausages to inhibit the growth of Listeria monocytogenes and Salmonella spp.

Reuterin is a bacteriocin produced by some strains of Lactobacillus reuteri. The strain used in this study was isolated from raw milk from a dairy farm nearby Ankara. Beef sausage is a long years produced bratwurst style meat product in Turkey, as well as in some other countries in the Mediterranean region. Sausages are produced by raw meat; sometimes lactic starter cultures are added or spontaneous fermentation is employed. The production and storage conditions of the product promotes the growth of Listeria monocytogenes and Salmonella spp. Although nitrate is added as an antimicrobial substance against many pathogens, sometimes however nitrate application is not preventive enough on the surface because of the natural film around the sausages. Since most of the contaminations take place at post production steps, pathogenic growth is more effective on the surface of the sausages in refrigerated conditions. In this study, reuterin was applied to the surface of the sausages in order to prevent the growth of these two pathogens along with nitrate used as an additive in the product. Reuterin has inhibited the growth of L. monocytogenes considerably but not of Salmonella spp. on the surface of the sausages.     

Growth and production of volatiles by Staphylococcus carnosus in dry sausages: Influence of inoculation level and ripening time

Three sausage batches inoculated with normal inoculation level of Pediococcus pentosaceus (5×10(6) CFU/g) and with low, intermediate, and high inoculation levels of Staphylococcus carnosus (10(5), 5×10(6), 5×10(7) CFU/g, respectively) were produced. Cell counts and formation of volatiles were followed throughout a ripening period of three weeks. The staphylococci exhibited the fastest growth in sausages with a low inoculation level, whereas growth was only moderate in sausages with a high initial level. Analysis of volatiles showed that methyl-branched aldehydes and acids, phenylacetaldehyde, 2-methyl-1-butanol, dimethyldisulphide and dimethyltrisulphide were produced in higher amounts in sausages with a high inoculation level of S. carnosus, whereas a low inoculation level correlated with high amounts of diacetyl, ethanol and ethyl esters. The levels of most compounds increased over time, but the amount of diacetyl was negatively correlated to ripening time. A negative interaction effect between inoculation level and ripening time was observed for the amounts of methyl-branched aldehydes.     

Development of Sausages Containing Mechanically Deboned Chicken Meat Hydrolysates

Pork meat sausages were prepared using protein hydrolysates from mechanically deboned chicken meat (MDCM). In terms of the color, compared to the controls before and after storage, the redness (a*) was significantly higher in sausages containing MDCM hydrolysates, ascorbate, and sodium erythorbate. After storage, compared to the other sausage samples, the yellowness (b*) was lower in the sausages containing ascorbate and sodium erythorbate. TBARS was not significantly different among the sausage samples before storage, whereas TBARS and DPPH radical scavenging activities were significantly higher in the sausagescontainingascorbate and sodium erythorbate, compared to the other sausage samples after 4 wk of storage. In terms of sensory evaluation, the color was significantly higher in the sausages containing MDCM hydrolysates, ascorbate, and sodium erythorbate, compared to the other sausage samples after 4 wk of storage. The “off‐flavor” and overall acceptability were significantly lower in the sausages containing MDCM hydrolysates than in the other sausage samples.     

发酵香肠乳酸菌筛选及其对产品品质的影响

利用香肠模型结合主成分分析（PCA），筛出了一株对香肠风味物质有显著提升的植物乳杆菌M-25(Lactobacillus plantarum,M-25)。将其添加到香肠中，以未接菌组作为对照，在川式香肠制作的第0、1、3、7、14 d对pH、Aw、色泽、过氧化值（POV）、硫代巴比妥酸（TBARS）以及挥发性风味物质进行了检测。应用偏最小二乘模型（PLS-DA），以VIP（投影中的变量重要性）>1,P<0.05作为筛选条件对香肠中的特征风味物质进行评价。结果表明，随发酵时间推移对照组和接种植物乳杆菌香肠的pH均先降低后缓慢上升；Aw显著降低（P<0.05）;POV和TBARS显著升高（P<0.05）；而色泽却无显著性差异（P>0.05）。与对照组相比，接种植物乳杆菌香肠的pH、Aw、POV和TBARS值均明显更低，且接种植物乳杆菌香肠中醇类、酮类和酯类物质均明显高于对照组，能明显提升特征风味物质（异戊酸、3-羟基-2-丁酮、苯乙醛和苯乙醇）的含量。综上所述，利用香肠模型筛选的植物乳杆菌M-25能有效提升香肠品质和风味特性。     

接种葡萄球菌和微球菌提高广式腊肠贮藏期间氧化稳定性的研究

本文旨在研究菌株接入广式腊肠延长其货架期机制。将从广式腊肠中依据其蛋白酶、脂肪酶和亚硝酸盐还原酶活性筛选出来的葡萄球菌H33B和微球菌X142B 2株菌株应用到腊肠中,首先测定各处理组中各分子量肽段的含量,然后用4种常见的抗氧化测定方法测定各处理组中小于5 ku肽段的抗氧化活性,最后对贮藏期间(25℃)腊肠脂肪氧化、蛋白氧化值和高铁肌红蛋白含量进行测定。结果表明接种菌株接入不仅能够增加腊肠中小分子肽的含量,还能增强对应处理组中肽的抗氧化性能;此外菌株的接入能够减缓广式腊肠贮藏期间氧化反应的程度,其中以接入混合菌组效果最明显。这些结果表明选择具有一定工艺学特性的菌株应用于广式腊肠中,能够减缓氧化反应的程度,从而有利于货架期的延长。