Entire Ripening Period Research Articles

Untargeted Metabolomics Combined with Sensory Analysis to Evaluate the Chemical Changes in Coppa Piacentina PDO during Different Ripening Times.

Ripening time is known to drive the chemical and sensory profiles of dry meat products, thus potentially affecting the final quality of the product. Starting from these background conditions, the aim of this work was to shed light, for the first time, on the chemical modifications of a typical Italian PDO meat product-namely, Coppa Piacentina-during ripening, to find correlations between its sensory quality and the biomarker compounds related to the progress of ripening. The ripening time (from 60 to 240 days) was found to deeply modify the chemical composition of this typical meat product, providing potential biomarkers of both oxidative reactions and sensory attributes. The chemical analyses revealed that there is typically a significant decrease in the moisture content during ripening, likely due to increased dehydration. In addition, the fatty acid profile showed that the distribution of polyunsaturated fatty acids significantly (p < 0.05) decreased during ripening, because of their high susceptibility to oxidation and conversion to intermediate and secondary molecules. An untargeted metabolomics approach, coupled with unsupervised and supervised multivariate statistics, highlighted a significant impact (prediction scores > 1) of lipid oxidation during ripening time, with some metabolites (such as γ -glutamyl-peptides, hydroperoxy-fatty acids, and glutathione) being particularly discriminant in predicting the changes observed. The discriminant metabolites were coherent with the progressive increase of peroxide values determined during the entire ripening period. Finally, the sensory analysis outlined that the highest degree of ripening provided greater color intensity of the lean part, slice firmness, and chewing consistency, with glutathione and γ-glutamyl-glutamic acid establishing the highest number of significant correlations with the sensory attributes evaluated. Taken together, this work highlights the importance and validity of untargeted metabolomics coupled with sensory analysis to investigate the comprehensive chemical and sensory changes to dry meat during ripening.

Biogenic amine production by nonstarter strains of Lactobacillus curvatus and Lactobacillus paracasei in the model system of Dutch-type cheese

The objective of the study was to assess the development of the biogenic amine content in model cheese samples individually inoculated with two biogenic amine producing non-starter lactic acid bacteria strains of Lactobacillus curvatus subsp. curvatus (DEPE T3 and DEPE T36) and two biogenic amine producing non-starter lactic acid bacteria strains of Lactobacillus paracasei (DEPE T51 and DEPE T52) over the course of a 90 day storage period (10 ± 1 °C). During the entire ripening period, the dominant biogenic amine was tyramine. After just two months of ripening, tyramine concentration 167 mg/kg was detected in the model cheeses with the DEPE T3 strain (moreover a total biogenic amine concentration was 220 mg/kg), whilst in the case of the DEPE T36 strain it was even 211 mg/kg of tyramine (sum of biogenic amine was 302 mg/kg). In the samples with the added DEPE T51 and DEPE T52 strains, tyramine concentration after 90 days of ripening almost reached the level of 50 mg/kg.

Fate of Listeria innocua during production and ripening of smeared hard cheese made from raw milk

The fate of 2 different Listeria innocua strains was analyzed during the production and ripening of smeared raw milk Greyerzer cheese (Gruyère). These strains were used as surrogates for the pathogenic Listeria monocytogenes, as they are physiologically very similar. Bacterial cells were added to the cheese milk at levels of 105 cfu/mL. During the first 24 h of cheese making, the number of the test strains decreased to a level of below 102 cfu/g. Obviously, the cooking temperature of 56°C and the subsequent slight temperature decrease to 50°C within 70 min contributed to a distinct reduction of Listeria counts. The counts in the cheese cores did not exceed 103 cfu/g within 12 wk of cheese ripening and Listeria was not detectable after 24 wk. In contrast to the cores of the cheeses of the 4 batches in this study, their rinds always contained a high listerial load of approximately 106 to 108 cfu/g throughout the entire ripening period. The smeared surface showed an increase of pH to alkaline values, corresponding to smear microbiota development. Coryneforms and Staphylococcus counts were stable at >107 cfu/cm2 over 175 d, whereas yeast counts decreased to about 105 cfu/cm2 at the end of ripening. The study shows that the smear culture had no noticeable anti-listerial potential. When removing the rind or portioning such smeared cheese loaves with a cutting device, a postprocess contamination of the core might occur, thus presenting a major hygienic risk.

Detection of different microenvironments and Lactobacillus sakei biotypes in Ventricina, a traditional fermented sausage from central Italy

The present study evaluated the physico-chemical and microbiological features of Ventricina, considering for the first time the presence of different compartments deriving from the technology of production. In fact meat pieces (pork muscle and fat cut into cubes of about 10–20cm3), mixed with other ingredients and then stuffed into pig bladder, are still distinguishable at the end of the ripening. They appear delimited on the outside by the casing and inside by thin layers consisting of spices (mainly red pepper powder), salt and meat juices. Our results showed that the exterior (portion of the product in contact with the casing), the interstice (area between the different cubes of meat or fat) and the heart (the inner portion of meat cubes) had distinctive values of pH and aw, and a typical microbial progression, so that they can be considered as different ecological niches, here called microenvironments. The study of lactic acid bacteria population, performed with PCR-DGGE and sequence analysis targeting the V1–V3 region of the 16S rRNA gene (rDNA), highlighted the presence of a few species, including Lactobacillus sakei, Lb. plantarum, Weissella hellenica and Leuconostoc mesenteroides. The RAPD-PCR analysis performed on Lb. sakei, recognised as the predominant species, allowed the differentiation into three biotypes, with that characterised by the highest acidifying and proteolytic activities and the highest ability to grow in the presence of sodium chloride prevailing. This leading biotype, detectable in the interstice during the entire ripening period, was isolated in the microenvironments exterior and heart starting from the 30th d of ripening, and it was the sole biotype present at the end of the ripening. The analysis of microenvironments through the scanning electron microscopy (SEM) evidenced the presence of micro-channels, which could favour the microbial flow from the interstice to the exterior and the heart. Moreover, the SEM analysis allowed the detection of biofilms, recognised as responsible for the correct colonisation of the different meat niches.

Valorization of indigenous dairy cattle breed through salami production

The aim of the research was to produce salami manufactured with meat of three different commercial categories of bovine breed: cow on retirement, beef and young bull. A total of six experimental productions, at small-scale plant, were carried out with and without starter culture inoculums. The evolution of physico-chemical parameters in all trials followed the trend already registered for other fermented meat products. Several LAB species were found during process with different levels of species diversity and frequency of isolation among inoculated (mainly Pediococcus pentosaceus and Staphylococcus xylosus) and uninoculated (mainly Enterococcus devriesei, Lactobacillus curvatus and Lactobacillus sakei) trials. Enterobacteriaceae were found at very low levels during the entire ripening period and no pathogenic bacteria were found in any samples. The multivariate analysis showed that starter inoculums and meat affected significantly the physico-chemical and the microbiological composition of salami. The sensory analysis evidenced the highest overall acceptability was displayed by salami produced with meat from cow on retirement.

Microbial analyses of traditional Italian salami reveal microorganisms transfer from the natural casing to the meat matrix

In this study the bacterial biodiversity, during the maturation process of traditional sausages (Salame Mantovano), produced with two different kinds of casing (hog middle or “Crespone” and hog bung or “Gentile”), was investigated by means of culture-dependent and -independent methods. In order to assess the natural variability linked to the type of casing used in production, the ingredients, as well as ripening conditions, were identical in both productions. The aim of the study was to understand the contribution of casing microflora during sausage ripening by identifying the dominant species and strains. The bacterial ecology of casings and salami at different ripening stages, as determined by plating, revealed higher staphylococci and enterococci counts for Gentile casing and for the entire ripening period of the salami studied. After molecular identification of 219 Lactobacilli and 225 cocci gram positive catalase positive (GPCP) isolates, the species most frequently isolated were Lactobacillus sakei, Lactobacillus curvatus, Staphylococcus xylosus, and Staphylococcus saprophyticus. Some L. sakei and S. saprophyticus strains, coming from casing, were also found in the salami at different times of ripening. A richer biodiversity was only detected at the beginning of maturation. We also report the first detection, by PCR–DGGE method, of Arcobacter marinus and Brochothrix thermosphacta species in casings and Kokuria salsicia in fresh sausage. Results suggesting that casing can be an important source of bacteria during natural fermentation when starter cultures are not used.

Ripening period influences fruit softening and antioxidative system of ‘Samar Bahisht Chaunsa’ mango

Increased respiration rate and textural softening in mango during fruit ripening limit its postharvest shelf life with poor quality. Changes in ethylene production, respiration rate, activities of fruit softening [exo-polygalacturonase (exo-PG), endo-polygalacturonase (endo-PG), pectin esterase (PE) and endo-1,4-β-d-glucanase (EGase)], and antioxidative [peroxidase (POX), catalase (CAT) and superoxide dismutase (SOD)] enzymes were studied in mango cv. ‘Samar Bahisht Chaunsa’ during ripening at ambient conditions (25±1°C; 60–65% RH). Ethylene production (0.01–0.34μmolkg−1h−1) and respiration rate (1.14–2.70mmol CO2kg−1h−1) showed quadratic and cubic increase respectively up to day-5 of fruit ripening and later on reduced as the fruit reached to fully ripe stage (day-9). Fruit showed a linear decreasing trend for fruit firmness (160.6–4.1N) during the entire ripening period. Fruit exhibited significant linear increase in the activities of endo-PG (4.11–8.15 viscosity changes mg−1proteinh−1), cubic increase for exo-PG (18.95–60.3μg gal acid mg−1proteinh−1) and EGase (3.96–9.52 viscosity changes mg−1proteinh−1) and cubic decrease in PE (0.93–0.19mM NaOH mg−1proteinh−1) enzymes during the entire ripening period. Linear decreasing trend for SOD (50.71–26.75Umg−1 protein) and cubic increasing trend for CAT (37.63–78.45Umg−1 protein) and POX (17.11–82.35Umg−1 protein) enzymes were observed during fruit ripening in ‘Samar Bahisht Chaunsa’ mango. Fruit showed linear increase in total antioxidant scavenging activities (766.87–478.41 IC50 value) up to day-7 and later on it decreased. Conclusively, along with the ethylene production and respiration rate, fruit ripening period was well associated with the activities of fruit softening and antioxidative enzymes of ‘Samar Bahisht Chaunsa’ mango fruit. As the ripening stage advanced, except PE and SOD, activities of fruit softening and antioxidative enzymes significantly increased in ‘Samar Bahisht Chaunsa’ mango fruit.

Comparison of culture-dependent and -independent methods for bacterial community monitoring during Montasio cheese manufacturing

The microbial community in milk is of great importance in the manufacture of traditional cheeses produced using raw milk and natural cultures. During milk curdling and cheese ripening, complex interactions occur in the microbial community, and accurate identification of the microorganisms involved provides essential information for understanding their role in these processes and in flavor production. Recent improvements in molecular biological methods have led to their application to food matrices, and thereby opened new perspectives for the study of microbial communities in fermented foods. In this study, a description of microbial community composition during the manufacture and ripening of Montasio cheese was provided. A combined approach using culture-dependent and -independent methods was applied. Culture-dependent identification was compared with 16S clone libraries sequencing data obtained from both DNA and reverse-transcribed RNA (cDNA) amplification and real-time quantitative PCR (qPCR) assays developed to detect and quantify specific bacterial species/genera ( Streptococcus thermophilus, Lactobacillus casei, Pediococcus pentosaceus, Enterococcus spp., Pseudomonas spp.). S. thermophilus was the predominant LAB species throughout the entire ripening period of Montasio cheese. The culture-independent method demonstrates the relevant presence of Pseudomonas spp. and Lactococcus piscium at the beginning of ripening. The culture-dependent approach and the two culture-independent approaches produced complementary information, together generating a general view of cheese microbial ecology.

Enzyme activity in Spanish goat's cheeses

Specific enzyme activity has been studied in Spanish goat's cheese. Neutral protease, aminopeptidase, and carboxypeptidase activity was analysed during the ripening of two Spanish goat's cheeses. One cheese was Majorero cheese from the island of Fuerteventura; the other was a soft cheese mould-ripened by P. candidum on the surface. The trend in neutral protease activity was rather similar in both cheeses over the ripening period. Protease activity was higher in Majorero cheese and higher on the surface than inside the mould-ripened cheese. Aminopeptidase activity also increased in both cheeses over the entire ripening period, but it was higher in the mould-ripened cheese than in the Majorero cheese. Carboxypeptidase activity was not recorded in either the Majorero or the soft cheese.

Effect of ripening temperatures on proteolysis and lipolysis in the outer and inner regions of Ras-type cheese made by various salting methods

Ras-type cheese was manufactured using different salting techniques including addition of salt to the curd at a level of 2% plus surface dry salting for 7 days, immersion in brine (20% NaCl) for 4 days or immersion in brine for 2 days plus surface dry salting for 5 days. Cheeses were matured at 7, 11, 15 or 20°C throughout the entire ripening period. Cheeses were organoleptically examined. Proteolysis and lipolysis in the outer and inner layers of the same cheese were assessed. Manufacture, without salt addition to the curd and brining or brine/dry salting, produced good quality cheese and accelerated proteolysis and lipolysis to a degree dependent on ripening temperature. Degradation of both αS 1 - and β-casein and production of free fatty acids were more rapid and extensive in the inner regions of the cheese than in the outer portion of the same cheese. High ripening temperatures enhanced the development of cheese flavour and this was associated with a marked reduction in the ripening period. Ripening at 20°C led to seepage of whey and fat from the cheese. Storage of cheese at 15°C appears to be suitable for maturing good quality Ras-type cheese in 8 weeks and it can be recommended for accelerating the ripening of this, and probably similar, cheese varieties.

Effect of Temperature at Ripening Period on the Eating Quality of Rice : Effect of temperature maintained in constant levels during the entire ripening period

Effect of Temperature at Ripening Period on the Eating Quality of Rice : Effect of temperature maintained in constant levels during the entire ripening period

Studies on Diagnosis of Rice Grains by Photometric Method : VI. Changes in translucency and color of rice kernel in the progress of maturation and dehydration

Changes in translucency and coloring of rice kernel in the course of maturation were examined photometrically by the "rice inspector". And the effects of dehydration, variety and vigor of kernel were also investigated. The results are summarized as follows: 1. Regardless of glutinosity, translucency of fresh kernel increased rapidly with the progress of ripening, until 15 to 20 days after anthesis, and thereafter the increment gradually declined toward maturity. The increase of translucency was considerably rapid in vigorous kernels as compared with weaker kernels. Some of the vigorous kernels of glutinous rice showed a little decline in their translucency in the last stage of maturity in accordance with the decrease of kernel moisture. 2. Fresh kernels of non-glutinous rice slightly increased their translucency by artifical drying in the later stages of ripening. On the other hand, those of glutinous rice markedly lost their translucency and turned opaque by drying. And this phenomenon (Ryokka) characteristic of glutinous rice was seen throughout the entire ripening period. 3. Another experiment on Ryokka cleared that in the course of artificial drying, fresh kernels of glutinous rice started to diminish their translucency at around 20% of moisture content and rapidly increased their opacity in the moisture range of 15 to 17%. 4. Greenish coloring of hulled rice attained its peak about 15 to 20 days after anthesis, and thereafter declined toward maturity in accordance with chlorophylous decomposition. 5. Red-brownish hue of the colored rice was remarkably deepened during maturation, especially in vigorous kernels. And this coloring tendency was more conspicuous for deeper-colored varieties. A test on artiticial drying of fresh kernel obviously showed that the dehydration of hulled rice encouraged its brownish coloring. 6. Results of some spectrophotometric investigation on rice extractives suggested that brownish coloring of rice kernel during ripening might be ascribed to bathochromic shift or bathochromic effect due to structural changes of polyphenolic tannin-like substances in rice bran.

Influence of Leafroll Virus on Composition of Burger Fruits

Levels of the principal organic acids, amino acids, and cations in fruits from healthy and leafroll-infected Burger vines, grafted onto Dogridge rootstock free of all known virus, were compared during the 1973 and 1974 seasons in a field trial at Davis. Total titratable acidity, and malate and tartrate, were significantly greater (P&lt;0.01) in fruits from leafroll-infected vines than in fruits from healthy vines, when compared on the same sampling date. Potassium, too, was significantly higher in fruits from leafroll-infected vines during the entire ripening period (August 19 to November 1). High correlations existed between potassium and total acidity, malate, and tartrate, indicating that the higher levels of these organic substances in infected fruits may have been due to the increased amounts of potassium in the fruits. The concentration of proline in fruits from infected vines followed the levels of soluble solids, and was significantly less (P&lt;0.05) than in healthy vines at all stages of fruit development. Arginine also was present in higher amounts in healthy fruits, compared to infected fruits, during early stages of fruit ripening. However, at the end of the ripening season, there was either no difference in arginine concentration of fruits, or infected fruits had somewhat higher arginine than did healthy fruits. Fruits from healthy or infected, cluster-thinned vines had higher levels of soluble solids, arginine, and proline than did fruits from vines with full crops. In contrast, concentrations of total acidity, tartrate, malate, and potassium were not significantly affected by crop level when compared on the same sampling date.

Influence of Leafroll Virus on Composition of Burger Fruits

Levels of the principal organic acids, amino acids, and cations in fruits from healthy and leafroll-infected Burger vines, grafted onto Dogridge rootstock free of all known virus, were compared during the 1973 and 1974 seasons in a field trial at Davis. Total titratable acidity, and malate and tartrate, were significantly greater (P&lt;0.01) in fruits from leafroll-infected vines than in fruits from healthy vines, when compared on the same sampling date. Potassium, too, was significantly higher in fruits from leafroll-infected vines during the entire ripening period (August 19 to November 1). High correlations existed between potassium and total acidity, malate, and tartrate, indicating that the higher levels of these organic substances in infected fruits may have been due to the increased amounts of potassium in the fruits. The concentration of proline in fruits from infected vines followed the levels of soluble solids, and was significantly less (P&lt;0.05) than in healthy vines at all stages of fruit development. Arginine also was present in higher amounts in healthy fruits, compared to infected fruits, during early stages of fruit ripening. However, at the end of the ripening season, there was either no difference in arginine concentration of fruits, or infected fruits had somewhat higher arginine than did healthy fruits. Fruits from healthy or infected, cluster-thinned vines had higher levels of soluble solids, arginine, and proline than did fruits from vines with full crops. In contrast, concentrations of total acidity, tartrate, malate, and potassium were not significantly affected by crop level when compared on the same sampling date.

Effect of gibberellin on the production of ethylene and on respiration rate in yellow transparent apples

The dependence of ethylene production and respiration rate on the concentration of gibberellin (GA) applied in water emulsion of lanoline to young fruits was studied in Yellow transparent apples. Ethylene production and respiration rate were slightly increased by GA treatment. The increased level was maintained throughout the entire ripening period, which was also apparent from the total amount of both released gases. A gas-chromatographic method, using a flame ionization detector for simultaneous determination of ethylene and CO2 in the atmosphere of experimental biological containers, is described in this paper. CO2 is hydrogenated to methan on Ni — ThO2 catalyst by hydrogen which is used as carrier gas. The gases pass the hydrogenating reactor after the separation in the Chromatographic column before entering the detector.

Studies on White-core Rice Kernel : III. Relations between white-core occurrence and development of starch tissue in rice kernel

In order to investigate the development of white-core structure in rice kernel, some observations and measurements were conducted on the cross sections of rice kernels. Results and discussion are summarized as follows: About 5 to 6 days after flowering, a radial arrangement of starch tissue which mainly consisted of thin cells became clear to be seen. And the thin cells especially along the dorso-ventral diameter remained thin and sometimes opaque through the entire ripening period. The radial tissue was well-arranged in the common kernels, whereas polygonal large-cells enclosing a bundle of thin-cells were observed in the white-core kernels. The progress of translucentization of starch tissue of white-core varieties was somewhat sluggish in early stages of ripening. Generally the growth of kernel was rather rapid on its abdominal side in early ripening stage except for several days after pollination and on its dorsal side in the later stages. The ventral side of the kernel of white core variety showed the better growth, especially at the sarly stage of the kernel development, compared with that of common variety. It is considered that vigorous developent of ventral side causes more but thinner cells in that side and thinner cells in the opposite side, resulting in the formation of inavcive tissues of thin cells along the dorso-ventral diameter, and censequently the occurrence of white core in those tissues.

Chemical Study of the Ripening Process of Bosc Pears

1. A study of the ripening process of Bosc pears held at 67⚬ F. has been made by means of chemical analyses of individual sample lots removed from the ripening room on each of 17-20 successive days. Pears of three different lots, picked ten days apart, were studied in this way and determinations made of total solids, alcohol insoluble residue, soluble solids, dextrose, levulose, sucrose, and sorbitol. 2. The losses of weight during the ripening period were recorded. The results of sugar and other determinations were calculated in terms of fresh weight at the time of sampling as well as in percentages of the original fresh weight. The latter method, involving correction for changes in effective size of sample taken, appears to give a more accurate method of studying the changes taking place during ripening. 3. A study of the sugar changes during ripening showed that levulose increased during the entire ripening period. Sucrose increased for the first six to eight days and then decreased throughout the rest of the period studied. Dextrose remained constant during the formation of sucrose, but increased later as sucrose disappeared. The increases in dextrose and levulose accompanying the decrease in sucrose were approximately equal, and their sum was about the same amount as that of the sucrose hydrolyzed. 4. The principal difference in the sugar content of fruit of the three pickings lay in the differences in the amounts of sucrose present. Throughout the ripening period the early picked fruit showed the least sucrose, the fruit of the commercial picking an intermediate amount, and the late picked fruit the highest values of this sugar. 5. Total sugars, calculated as the sum of dextrose, levulose, and sucrose, increased during the ripening process; this increase was considerably greater than could be accounted for by the observed decreases in the alcohol insoluble residue. 6. Sorbitol was identified as a constituent of Bosc pears, and a quantitative method was devised for its measurement. Sorbitol was observed to decrease during the ripening process in fruit of all three pickings, and these decreases were large enough to account for the observed increases in total sugars.