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.     

Microbial and physico-chemical changes during the ripening of dry fermented sausages superficially inoculated with or having added an intracellular cell-free extract of Penicillium aurantiogriseum

The effect of inoculation of the "salchichón" (dry fermented sausage) surface with an atoxygenic, proteolytic and lipolytic strain of Penicillium aurantiogriseum and/or the addition of an intracellular cell-free-extract (ICFE) of the same mould on the ripening process was studied. Four batches of salchichón were manufactured: control, superficially inoculated, added with the intracellular cell free extract and combination of both treatments. Superficial mould modified Micrococcaceae counts, pH, free amino acids, lipid fractions, TBARS and some organic acids. The ICFE degraded free amino acids, producing a rise in ammonia. Both treatments combined accelerate the proteolysis and lipolysis of the sausages and also the further amino acid degradation.     

Characterization of aromatic properties of old-style cheese starters

Old-style cheese starters were evaluated to determine their ability to produce cheese aroma compounds. Detailed analyses of the aroma-producing potential of 13 old-style starter cultures were undertaken. The proteolytic profile of the starters was established by an accelerated ripening study using a model cheese slurry and compared with those of a commercial aromatic starter and commercial Cheddar cheeses. To evaluate the aromatic potential of the starter cultures, quantification of free amino acids liberated and volatile compounds after 15 d of ripening at 30°C as well as sensory analysis were carried out. Results showed that proteolysis patterns of all 13 starter cultures in the curd model were comparable to those of commercial Cheddar cheeses. All tested cultures demonstrated the ability to produce high amounts of amino acids recognized as precursors of aroma compounds. Several differences were observed between the starters and commercial Cheddar cheeses regarding some amino acids such as glutamate, leucine, phenylalanine, proline, and ornithine, reflecting the various enzymatic systems present in the starters. Starters Bt (control) and ULAAC-E exhibited various significant differences regarding their free amino acid profiles, as confirmed by sensory analysis. In addition, identification of volatile compounds confirmed the presence of several key molecules related to aroma, such as 3-methylbutanal and diacetyl. Besides the aroma-producing aspect, 2 starters (ULAAC-A and ULAAC-H) seem to possess an important ability to generate large amounts of γ-aminobutyric acid, which contributed up to 15% of the total amino acids present in the model curd after 15 d ripening. γ-Aminobutyric acid is an amine well-known for its antihypertensive and calming effects.     

The development of free amino acids and volatile compounds in cheese ‘Oloumoucké tvarůžky’ (PGI) during ripening

Twenty‐two free amino acid (FAA) concentrations were observed during manufacture (7 days) and ripening period (42 days follow‐up) of Olomoucké tvar??ky (PGI, smear acid cheese). During the ripening period, the amounts of volatile compounds and selected sensory attributes were also analysed. The free amino acids were determined by means of ion‐exchange chromatography, and the volatile compounds were detected and identified using HS‐SPME coupled with GC/MS method. The development of the individual FAA content positively correlated with the ripening period (r = 0.7734–0.9229; P < 0.01). Forty‐six volatile compounds (14 alcohols; 10 esters; 7 ketones; 5 acids; 4 aldehydes; 3 sulphur compounds; 2 phenol compounds; and 1 terpene) were identified. Concentrations of several compounds increased (e.g. 3‐methylbutanal, 2‐butanol, 2‐butanone; P < 0.05) or decreased (e.g. dimethyldisulphide, methanethiol, 2‐phenylethylacetate, methylbutyric acid; P < 0.05) over cheese ageing. The results gave information about the development of sensory active substances and its precursors in Olomoucké tvar??ky during ripening. In conclusion, we found that free amino acid concentrations and sulphur compounds are positive with improved flavour.     

Generation of volatile flavour compounds as affected by the chemical composition of different dry-cured ham sections

The composition of different dry-cured ham sections has been determined in order to study their contribution to flavour generation. The proteins, free amino acids, free fatty acids and volatile compounds were analysed in different sections of dry-cured hams with 7 and 12 months of processing. The main differences among sections were detected in free amino acids and volatile compounds. To sum up, there was a higher concentration of free amino acids in the centre section than in the butt and shank sections. However, after 12 m of ripening the difference among sections was lower and only the butt was the one with the lowest concentration. Similar results were obtained in the content of volatile compounds, the centre part of the hams contained a higher proportion of volatile compounds after 7 m of ripening than the shank and butt sections. Nevertheless, in 12 months dry-cured hams there are changes in the proportions of volatile compounds being the centre section the one with the highest proportion of volatile compounds due not only to the higher concentration of free amino acids but also to the oxidation of unsaturated fatty acids.     

Volatile composition and sensory properties of industrially produced Idiazabal cheese

The volatile composition and sensory properties of industrially produced Idiazabal cheeses made from ewes’ raw milk (RM) or pasteurised milk (PM) and with addition of different starter cultures were compared. Cheeses were analysed at 90 and 180 d of ripening. Acids were the major volatile compounds in RM cheeses. Methyl ketones were the major volatile compounds in PM cheeses at 90 ripening days. However, the content of acids strongly increased with ripening whereas the content of ketones decreased in PM cheeses. The concentration of esters was higher in RM cheeses than in PM cheeses. No differences were found in the content of alcohols. Most aldehydes, hydrocarbons, terpenes and furans identified were minor volatile compounds in both RM and PM cheeses. In RM cheeses, characteristic sensory attributes for the aroma of Idiazabal cheese were present at 3 months, whereas in PM cheeses those desirable sensory attributes did not appear until 6 months of ripening.     

Volatile compounds, odor, and aroma of La Serena cheese high-pressure treated at two different stages of ripening

La Serena cheeses made from raw Merino ewe's milk were high-pressure (HP) treated at 300 or 400 MPa for 10 min on d 2 or 50 after manufacture. Ripening of HP-treated and control cheeses proceeded until d 60 at 8°C. Volatile compounds were determined throughout ripening, and analysis of related sensory characteristics was carried out on ripe cheeses. High-pressure treatments on d 2 enhanced the formation of branched-chain aldehydes and of 2-alcohols except 2-butanol, but retarded that of n-aldehydes, 2-methyl ketones, dihydroxy-ketones, n-alcohols, unsaturated alcohols, ethyl esters, propyl esters, and branched-chain esters. Differences between HP-treated and control cheeses in the levels of some volatile compounds tended to disappear during ripening. The odor of ripe cheeses was scarcely affected by HP treatments on d 2, but aroma quality and intensity scores were lowered in comparison with control cheese of the same age. On the other hand, HP treatments on d 50 did not influence either the volatile compound profile or the sensory characteristics of 60-d-old cheese.     

Auxin treatment of pre‐veraison grape (Vitis vinifera L.) berries both delays ripening and increases the synchronicity of sugar accumulation

Background and Aims: Pre‐veraison auxin treatments can delay grape berry ripening, but there is little information about their effects on berry development and wine composition. The aim of this study was to further investigate these effects and explore the practical implications of delaying ripening. Methods and Results: Treatment of pre‐veraison Vitis vinifera L. cv. Shiraz berries with 1‐naphthaleneacetic acid (NAA) significantly delayed ripening as measured by the accumulation of total soluble solids (TSS) and anthocyanins. The onset of the post‐veraison phase of berry size increase was delayed in NAA‐treated fruit, but these fruit were significantly larger than Control fruit at harvest. NAA‐treatments significantly increased the synchronicity of berry sugar accumulation. GC‐MS analysis of wine headspace volatiles showed significant, but largely small, differences in the concentration of 19 compounds. No significant difference in sensory properties was found between replicate small‐scale wine lots made from Control and NAA‐treated fruit. Conclusions: Auxin treatment delayed berry ripening, increased the synchronicity of sugar accumulation between berries, increased berry size and changed the levels of some volatile compounds, but did not affect wine sensory properties. Significance of the Study: We propose that NAA sprays might be used to delay grape berry ripening and increase the synchronicity of sugar accumulation, and therefore ripening, without deleterious effects on wine quality. This may be useful in controlling winery intake and fruit composition.     

Effect of mesophilic lactobacilli and enterococci adjunct cultures on the final characteristics of a microfiltered milk Swiss-type cheese

The effect of four associations of adjunct cultures composed of mesophilic lactobacilli and enterococci, either solely or combined, on the microbiological, biochemical and sensory characteristics of Swiss-type cheese made using microfiltered cows’ milk and supplemented with propionibacteria was studied. The global pattern of growth was similar to that generally observed in raw milk cheese and interactions between microflora were highlighted during ripening. Enterococci, which negatively affected the survival of streptococci starters, seemed to play a limited role in the formation of volatile compounds, probably due to their low levels throughout ripening. On the contrary, mesophilic lactobacilli, which affected the evolution of propionibacteria, enterococci and L. delbrueckii subsp. lactis starter counts, modified free amino acid content, production of volatile compounds and organoleptic properties of mature cheese. This population appeared to be of major importance in the formation of cheese flavor as it was positively related to numerous potential flavor compounds such as alcohols and their corresponding esters, acetaldehyde and 4-methyl-4-heptanone. The original mesophilic lactobacilli present in milk could play an important role in the sensorial diversity of raw milk Swiss-type cheeses such as Comte.     

Enhancement of the flavour development of dry fermented sausages by using a protease (Pronase E) and a cell‐free extract of Penicillium camemberti

The present work was an attempt to improve the organoleptic properties of dry fermented sausages by enhancing the release of amino acids and their further transformation into ammonia, ketoacids and some volatile compounds responsible for the ripened flavour. For this purpose a protease (Pronase E from Streptomyces griseus) and a cell‐free extract (CFE) of a Penicillium camemberti strain selected for its L ‐amino‐oxidase activity were used. The addition of Pronase E alone led to a large increase in the content of free amino acids. The CFE showed deaminative activity, which gave rise to the accumulation of some important volatile compounds such as 2‐methylpropanal and 2‐ and 3‐methylbutanal. Organoleptic analysis reflected an improvement in the quality of the sausages, especially when the two treatments were combined. © 2002 Society of Chemical Industry     

Generation of non-protein nitrogen and volatile compounds by Penicillium chrysogenum Pg222 activity on pork myofibrillar proteins

A non-toxigenic strain of proteolytic Penicillium chrysogenum Pg222 isolated from dry-cured ham was tested for its ability to generate non-protein nitrogen (NPN) and volatile compounds from muscle myofibrillar proteins. The activity of mold led to higher accumulation of non-protein and amino acidic nitrogens than control samples. Volatile compound analysis revealed the presence of branched compounds, such as 3-methylbutanal and 3-methylbutanol only in samples inoculated with the mold. Similarly, compounds such as ethanol, propanol and 2-methoxy ethanol were detected only in inoculated samples at all sampling time. 3- and 2-methylpentane, benzoic and acetic acids, 2-butanone and 2-ethylhexanol, pyridine and 3-carene were detected occasionally, but only in the Pg222 batch. The proteolytic activity of P. chrysogenum Pg222 lead to accumulation of soluble NPN compounds, in addition to the generation of volatile compounds of great interest for dry-cured meat products. Therefore, this mold could be appropriate to be used as a non-toxigenic starter culture during the ripening of dry-cured meat products to stimulate proteolysis and flavour development.     

Use of bacterial extracts to enhance amino acid breakdown in dry fermented sausages

The effect of the intracellular cell-free extracts (ICFEs) of two bacterial strains (Lactobacillus sakei GO and Bacillus pumilus) on the amino acid catabolism and the sensory properties of dry fermented sausages, was investigated. Extracts were added to sausages alone or in combination with a protease, papain. Amino acid breakdown was monitored by the changes in free amino acids, ammonia and amine content during the ripening process. A 15% decrease in the content of free amino acids was observed in sausages added with the ICFE from L. sakei GO. Furthermore, the extract of L. sakei GO significantly reduced (54-68%) the content of the amino acids considered as precursors of the typical ripened flavour, i.e., valine, leucine and isoleucine. Chemical changes were not reflected in a significant improvement of the sensory quality of sausages added with the ICFEs. The potential use of the bacterial ICFEs studied in the present work for the manufacture of dry fermented sausages, and its comparison with the use of fungal extracts, are discussed.     

Contribution of a selected fungal population to proteolysis on dry-cured ham

The proteolytic changes taking place in dry-cured hams lead to increases in free amino acids. Such free amino acids not only contribute to flavour, but also serve as precursors of volatile compounds. Several months of ripening time are required to allow the particular flavour to develop. The fungal population allowed to grow on the surface of some types of dry-cured could play a key role on proteolysis, as it has been shown for dry-cured sausages. The purpose of this work was to study the possible contribution of fungi to proteolysis in dry-cured ham. For this, a strain each of non-toxigenic Penicillium chrysogenum (Pg222) and Debaryomyces hansenii (Dh345), selected for their proteolytic activity on myofibrillar proteins, were inoculated as starter cultures. Changes in the high ionic strength-soluble proteins of an external muscle (adductor) revealed in only 6 months higher proteolysis in the inoculated hams when compared to non-inoculated control hams. Proteolytic strains among the wild fungal population on non-inoculated control hams prevented from obtaining similar differences at the end of processing. However, inoculation with Pg222 and Dh345 led to higher levels for most free amino acids at the external muscle in fully dry-cured hams. In addition, the concentration for some of the more polar free amino acids (i.e. Asp, Glu, Ser and Gln) in inoculated hams was higher at external than at internal (biceps femoris) muscles. These promising results deserve further studies to know the impact of a selected fungal population on the volatile compounds and sensory properties of dry-cured ham.     

酸浆豆腐后熟过程中风味物质的形成途径分析

采集不同后熟阶段的酸浆豆腐为样本，对其游离氨基酸、有机酸、挥发性风味物质进行测定。结果显示，游离氨基酸和有机酸是滋味物质的主要来源，其中酸味氨基酸是主要的呈味物质，在不同的后熟阶段占总氨基酸的33%～35%。后熟过程中乳酸、乙酸和柠檬酸3 种有机酸是主要呈味物质且含量最高，其总量约占有机酸总量的50.08%～65.00%。后熟过程中共检测到84 种风味化合物，包括醛类、醇类、酚类、呋喃类等化合物，共同赋予酸浆豆腐独特的酵香风味。     

Cheese ripening in nonconventional conditions: A multiparameter study applied to Protected Geographical Indication Canestrato di Moliterno cheese

A multiparameter study was performed to evaluate the effect of fondaco, a traditional ripening cellar without any artificial temperature and relative humidity control, on the chemical, microbiological, and sensory characteristics of Protected Geographical Indication Canestrato di Moliterno cheese. Ripening in such a nonconventional environment was associated with lower counts of lactococci, lactobacilli, and total viable bacteria, and higher presence of enterococci, in comparison with ripening in a controlled maturation room. Moreover, fondaco cheese underwent accelerated maturation, as demonstrated by faster casein degradation, greater accumulation of free AA, and higher formation of volatile organic compounds. Secondary proteolysis, as assessed by liquid chromatography-mass spectrometry of free AA and low molecular weight peptides, did not show any qualitative difference among cheeses, but fondaco samples evidenced an advanced level of peptidolysis. On the other hand, significant qualitative differences were observed in the free fatty acid profiles and in the sensory characteristics. Principal component analysis showed a clear separation of the fondaco and control cheeses, indicating that ripening in the natural room conferred unique sensory features to the product.     

Combined use of Pronase E and a fungal extract (Penicillium aurantiogriseum) to potentiate the sensory characteristics of dry fermented sausages

A combination of an extract of Penicillium aurantiogriseum and Pronase E was used in an attempt to enhance the sensory characteristics of dry fermented sausages, specifically, a salami-like one named "salchichón". The addition of Pronase E alone (600 units/kg) produced a rise in free amino acids and biogenic amines and also an increase in the ammonia content. Addition of the protease and fungal extract (100.87 mg protein/kg of mixture) brought about a decrease in the level of free amino acids and a larger increase in the ammonia content than the batch added with only Pronase E. There was also an increase in the amount of specific volatile compounds such as 2- and 3-methylbutanal, 2- and 3-methylpropanal and 2- and 3-methyl-1-butanol produced by the breakdown of amino acids in these fermented sausages. Values of pH, a(w) and dry matter were not affected by addition of the protease or fungal extract. In contrast, addition of Pronase E produced a notable change in the textural characteristics, reducing the hardness, cohesiveness, gumminess, chewiness and cutting force. Sensory analysis showed that fermented sausages manufactured with Pronase E and Penicillium aurantiogriseum extract had better odour, flavour, texture and, as a consequence, better general acceptability.     

Proteolysis in dry fermented sausages: The effect of selected exogenous proteases

The effect of three commercial proteases (pronase E from Streptomyces griseus, aspartyl proteinase from Aspergillus oryzae and papain) on protein breakdown and the sensory characteristics of dry fermented sausages was investigated. Water soluble, non-protein, 5% phosphotungstic acid soluble, 5% sulphosalicylic acid soluble and total volatile basic nitrogen contents increased during fermentation, stabilizing later until the end of ripening (26th day). Nitrogen values were always greater in the aspartyl proteinase added batch in comparison with the other protease added batches. Total free amino acid changes showed a similar pattern to those observed for the 5% sulphosalicylic acid soluble nitrogen. The electrophoretic studies demonstrated that proteolysis of high molecular weight myofibrillar and sarcoplasmic proteins was more prominent in protease added batches. It was especially intensive in papain one. The dominant amino acids at the end of ripening were similar in all batches. Tyramine and histamine increased throughout ripening. No significant differences in sensory properties were found between control and pronase E and papain added batches, but they were significantly different (p < 0.01) from the sausages containing aspartyl proteinase, due to an excessive softening. The effect of exogenous enzyme addition on the flavour potentiation of dry fermented sausage is discussed.     

Effect of the fungal protease EPg222 on proteolysis and texture in the dry fermented sausage ‘salchichón’

Proteolytic activity of the fungal protease EPg222 and its effect on the texture of the dry fermented sausage ‘salchichón’, which has a long ripening process, was assayed. Samples with enzyme added showed a significant reduction of myofibrillar protein concentration during the ripening period, compared with a control, and proteolytic activity of the enzyme led to a higher accumulation of non‐protein and ‐amino acid nitrogen. Analysis of volatile compounds in ripened dry fermented sausages revealed that only in EPg222 batches were branched compounds derived from amino acids catabolism detected that are associated with the flavour of dry cured meat products. The texture profile analysis showed reduction in hardness, gumminess and chewiness values in treated compared with control sausages. The effect of this enzyme could be of great interest in stimulating proteolysis, in flavour development and in reducing the hardness of dry fermented sausages produced by a long ripening process. Copyright © 2004 Society of Chemical Industry     

解淀粉芽孢杆菌GSBa-1凝乳酶在马苏里拉干酪中的应用

对分离自酒曲的1 株解淀粉芽孢杆菌GSBa-1发酵所产凝乳酶进行研究,该酶凝乳活力高而蛋白水解活力低,纯酶凝乳活力可达1.46×106 SU/g;使用该凝乳酶和商品凝乳酶制作马苏里拉干酪,并对干酪理化成分、成熟过程中pH值和微生物指标及干酪成熟前后质构特性、游离脂肪酸、可溶性蛋白、风味和干酪性能等指标进行对比分析。结果显示,理化成分上菌株凝乳酶与商品凝乳酶制作的干酪相接近（P＜0.05）。干酪在成熟过程中,发酵剂存活数先增加后减少,但其差异不大;菌株凝乳酶制作的干酪pH 4.6可溶性蛋白含量较多,干酪的游离氨基酸总量（76 mg/100 g）也高于商品凝乳酶制作的干酪游离氨基酸总量（55.3 mg/100 g）;菌株凝乳酶制作的干酪质构特性优于商品凝乳酶制作的干酪;电镜结果显示,菌株凝乳酶制作的干酪内部网状结构更充实;菌株凝乳酶具有稍强的蛋白水解活力,导致其制作的干酪风味物质种类多于商品凝乳酶制作的干酪,风味物质更加丰富。干酪样品的保形性和拉丝性实验测定结果显示,2 种凝乳酶制作的干酪性能差异不大（P＞0.05）;对2 种凝乳酶制作的干酪进行感官评定,其总评分相接近。以上结果表明,解淀粉芽孢杆菌GSBa-1凝乳酶在一定程度上可代替小牛凝乳酶应用于马苏里拉干酪的生产。