Carbohydrate changes in ripening Capsicum annuum in relation to textural degradation

 Within 8 days of harvest, fruits of Capsium annum showed striking changes in texture when ripened at room temperature. Physiologically, they showed a significant weight loss and organoleptically, a change in textural firmness which was evident microscopically, as extensive cellular damage. The associated biochemical changes during ripening were: (1) an increase in free-sugar levels, (2) an increase in in situ hydrolysis of some hemicellulose fractions (Hem a, b and c) and (3) a general increase in the activity of cellulase, α-mannosidase, laminarinase, polygalacturanase, galactanase, mannanase, β-galactosidase and hemicellulase (HCe) activity on Hem b and c. In contrast the activity of xylanase, pectin methyl esterase and HCe on Hem a decreased during ripening. Cold storage (8°C) held textural changes in check, resulting in a longer shelf-life for cold-stored fruits compared to fruits stored at room temperature. Received: 14 May 1997     

Prediction of the ripening times of Manchego cheese using multivariate statistical analyse: a preliminary study

 Multiple linear regression, principal component regression, and partial least squares (PLS) regression were used to calculate ripening time in standard Manchego cheeses based on water activity (Aw), pH, and other proteolysis parameters. The root mean square error of prediction by cross-validation was used to study the prediction accuracy of the models. PLS regression yielded the best predictions of ripening time and was used to predict the ripening times of eight commercial Manchego cheeses. Received: 8 October 1997 / Revised version: 20 January 1998     

Production of reduced-calorie grape juice jelly with gellan, xanthan and locust bean gums: sensory and objective analysis of texture

 The production of reduced-calorie grape juice jellies with gellan, xanthan and locust bean gums (LBG) was studied. Twenty formulations of grape juice jelly were prepared according to a second-order composite rotatable design (with six central points). Response surface methodology (RSM) was used to optimise jelly formulation using as independent variables: total sugar content, ranging from 14 to 46°Brix; and total gum concentration ranging from 0.30 to 0.70% (w/v), with the proportion of gums in the mixture xanthan:LBG:gellan ranging from 5:5:90 up to 45:45:10. The processing temperature used was 90°C for complete solubilisation of gums. The dependent variables were objective measures of texture and a parameter obtained from sensory analysis, the overall balance (B), which represents the overall evaluation of the jelly. The resulting polynomial equation (R ² = 0.929) revealed that a jelly produced with white grape juice, total sugar with sucrose equal to 39.3°Brix, and, 0.54% (w/v) of total gum added in the proportions of: 1:1:1.7 (gellan:xanthan:LBG) had a maximum value of B. The sensory-optimised jelly was objectively characterised for texture and the model was tested. The texture characteristics, i.e. gel hardness, cohesiveness and springiness, were found to be similar to those of a reference product, a previously developed reduced-calorie grape juice jelly with low methoxyl pectin. Received: 12 June 1997 / Revised version: 21 August 1997     

Prediction of the ripening times of Manchego cheese using multivariate statistical analyse: a preliminary study

 Multiple linear regression, principal component regression, and partial least squares (PLS) regression were used to calculate ripening time in standard Manchego cheeses based on water activity (Aw), pH, and other proteolysis parameters. The root mean square error of prediction by cross-validation was used to study the prediction accuracy of the models. PLS regression yielded the best predictions of ripening time and was used to predict the ripening times of eight commercial Manchego cheeses. Received: 8 October 1997 / Revised version: 20 January 1998     

The effect of postmortem processing treatments on quality attributes of raw Atlantic salmon (Salmo salar) measured by sensory and instrumental methods

The main objective of this study was to compare the effects of three different processing treatments on sensory attributes and instrumental quality measurements of raw Atlantic salmon (Salmo salar) fillets. Salmon was either pre-rigor filleted and restricted or allowed to contract (Vacuum-PRE and Contracted-PRE, respectively) or post-rigor filleted (POST). Sensory evaluation (appearance, flavour, texture) and instrumental quality measurements (colour, texture, fat, astaxanthin, liquid holding capacity) were performed at 5–7 days postmortem. Sensory evaluation revealed that Vacuum-PRE fillets had less desirable quality attributes than the other treatment groups, with higher scores for tenderness and whiteness and lower scores for hardness and colour intensity. The observed changes in fillet height between the treatment groups indicated that the immediate vacuum packaging of the Vacuum-PRE fillets had limited their contraction during rigor mortis development, resulting in the negative effects observed on quality. This implicates that the well-known positive effects of pre-rigor filleting regarding colour and texture can be reduced or even abolished if the fillets are restricted from contraction during rigor mortis development.     

Fatty acids of a salami-type sausage made of Baltic herring fillets, pork and lard

 The fatty acid composition of "fish wurst", a fermented salami-type sausage made of pork, lard and Baltic herring fillets (Clupea harengus var. membras) was investigated. Changes in the proportions of the 35 most abundant fatty acids were examined throughout the 1-month ripening period followed by a 4-month storage period. The fat composition of the product was stable (32–35%) and retained the characteristics of the main ingredients: oleic acid (37.4%, mean of three production batches) palmitic acid (23.7%) and linoleic acid (10.7%) from lard and fish, stearic acid (11.7%) mainly from lard, and palmitoleic acid (3.0%) and long-chain (C20–C24), polyunsaturated fatty acids (c.a. 6%) mainly from fish. During the 4-week ripening period a statistically significant increase (P≤0.05) was detected in the proportions of minor fatty acids only, i.e. eicosenoic acid (20 : 1n-9), eicosadienoic acid (20 : 2n-6), docosadienoic acid (22 : 2n-6) and docosatrienoic acid (22 : 3n-3). During the 4-month storage of the ripe sausage, the fatty acid composition stabilized. Only the proportion of stearic acid increased significantly during storage, from 11.7% to 12.5%. Received: 23 January 1998 / Revised version: 1 April 1998     

Fatty acids of a salami-type sausage made of Baltic herring fillets, pork and lard

 The fatty acid composition of "fish wurst", a fermented salami-type sausage made of pork, lard and Baltic herring fillets (Clupea harengus var. membras) was investigated. Changes in the proportions of the 35 most abundant fatty acids were examined throughout the 1-month ripening period followed by a 4-month storage period. The fat composition of the product was stable (32–35%) and retained the characteristics of the main ingredients: oleic acid (37.4%, mean of three production batches) palmitic acid (23.7%) and linoleic acid (10.7%) from lard and fish, stearic acid (11.7%) mainly from lard, and palmitoleic acid (3.0%) and long-chain (C20–C24), polyunsaturated fatty acids (c.a. 6%) mainly from fish. During the 4-week ripening period a statistically significant increase (P≤0.05) was detected in the proportions of minor fatty acids only, i.e. eicosenoic acid (20 : 1n-9), eicosadienoic acid (20 : 2n-6), docosadienoic acid (22 : 2n-6) and docosatrienoic acid (22 : 3n-3). During the 4-month storage of the ripe sausage, the fatty acid composition stabilized. Only the proportion of stearic acid increased significantly during storage, from 11.7% to 12.5%. Received: 23 January 1998 / Revised version: 1 April 1998     

Chymotrypsin and general proteolytic activities in muscle of Engraulis encrasicolus and Engraulis anchoita during the ripening process

 During fish ripening, biochemical changes occur that give rise to the organoleptic properties characteristic of the product. Enzymes play a key role in this ripening process, although it is not known exactly which enzymes are involved. We investigated the effects of the gutting method (nobbing only, or nobbing and butterflying) and addition of cathepsin C on general proteolytic activity, chymotrypsin activity, pH and organoleptic characteristics during brine ripening of fresh Engraulis encrasicolus. We also monitored these variables during brine ripening of frozen/thawed E. encrasicolus and E. anchoita. Butterflied fish ripened more rapidly than fish prepared by the traditional method (nobbing only). Inclusion of cathepsin C in the brine had a negative effect on texture (very firm, low juiciness) but a positive effect on flavour, which was more intense. Frozen/thawed fish were successfully ripened, giving a final product with fully acceptable organoleptic characteristics. In all batches except the E. anchoita batch both general proteolytic activity and chymotrypsin activity increased rapidly after immersion in brine, then dropped gradually over the ripening period. Received: 7 July 1999     

Effects of the smoking process on odour characteristics of smoked herring (Clupea harengus) and relationships with phenolic compound content

The relationship between smoking parameters and odour characteristics, evaluated by a trained sensory panel, were studied on smoked herring. In addition, a possible correlation between the content of 10 phenolic compounds and sensory perceptions was investigated. Five smoking techniques were applied, combining smoke production conditions, performed by pyrolysis of beech wood sawdust or by friction of beech wood log, with smoke deposition, either in a controlled kiln (traditional smoking) or by an electrostatic process. In the fifth smoking technique, a purified condensate of beech smokes was vaporised on fish fillets in the smokehouse. The time of smoking was 3 h for traditional smoking and the liquid smoke atomisation process and 12 min for the electrostatic method. The effects of three smoking temperatures (16, 24, 32 °C) were tested for both the traditional and the liquid smoke atomisation processes, as well as the effect of the position of the exhaust valve in the smokehouse in the case of the traditional method. Two different voltages were applied for the electrostatic process, 37 and 42 kV.     

Identification and sensory evaluation of flavour enhancers in Japanese traditional dried herring (Clupea pallasii) fillet

Flavour-enhancing components of dried herring fillet (migaki-nishin in Japanese) were isolated and evaluated for their effects on sensory perception. Sensory evaluation revealed that addition of dried herring fillet water-soluble extracts to Japanese noodle soup significantly (P < 0.05) enhanced soup flavour characters, such as thickness, mouthfulness and continuity. The extracts were fractionated by dialysis and chromatography. Fractions containing flavour enhancers were isolated by sensory perception. Results from instrumental analyses showed that the kokumi flavour enhancers in dried herring fillet were creatine and creatinine.     

Physicochemical,microbiological, textural and sensory changes during the ripening of pasteurised goat milk cheese made with plant coagulant (Cynara scolymus)

This study describes the changes that occur during the ripening of cheeses made with a plant coagulant derived from artichoke flowers (Cynara scolymus). The results indicate that the physicochemical composition during ripening evolves similarly to other cheeses. The texture and sensory features of the cheeses during ripening evolved differently from that observed for other goat cheeses. Although it is common for a bitter taste to develop during the ripening of cheeses elaborated with plant coagulants, bitterness was scored very low in the cheeses made with artichoke, so that these cheeses could be suitable for marketing.     

Seasonal variations in the free fatty acid composition of Manchego cheese and changes during ripening

 This paper examines the evolution of the free fatty acid concentration in Manchego cheese during ripening (up to 150 days) and in two different cheesemaking seasons (autumn and winter). Factorial analysis of the principal components showed that short-chain fatty acids were the variables that best correlated (81% of the total variance explained) with the samples when distributed according to ripening time. These fatty acids likewise differentiated autumn and winter samples. Received: 30 April 1999 / Revised version: 5 July 1999     

Secondary proteolysis in Serra cheese during ripening and throughout the cheese-making season

 Experimental Serra cheeses were manufactured from raw ewe’s milk and thistle flowers following a two-way factorial design. The content of nitrogen soluble in water (WSN), in 2% trichloroacetic acid (2% TCA-N), in 12% TCA (TCA-N) and in 5% phosphotungstic acid (5% PTA-N), and the pH and salt-in-moisture concentration were measured throughout the ripening period (sampling at 0, 7, 21 and 35 days) and the cheese-making season (sampling in November, February and May). Proteolysis in 35-day-old Serra cheese was quantitatively high [average values of 34.6% and 11.9% for WSN/TN (total nitrogen) and 2% TCA-N/TN, respectively], but qualitatively low (average values of 5.8% and 1.2% for 12% TCA-N/TN and 5% PTA-N/TN, respectively). The ratios WSN/TN and 2% TCA-N/TN were lowest for cheeses ripened in February, whereas the ratio 12% TCA-N/TN was highest for cheeses ripened in November. By 35 days of ripening, the average pH and salt-in-moisture concentration values were 5.2 and 4.8%, respectively. No correlation was found to occur between the measured pH or salt-in-moisture concentration and the values of soluble nitrogen fractions throughout the cheese-making season. Received: 14 February 1996/Revised version: 4 June 1996     

Oxidative and sensory changes during bulk and retail storage of hot-filled turkey casserole

 Oxidative and sensory changes in hot-filled turkey casserole were investigated during bulk storage at 3°C and during retail storage at 4°C. Oxidative changes, assessed as warmed-over flavour (WOF) by a trained sensory panel or determined as levels of thiobarbituric acid reactive substances (TBARS), showed no development during bulk storage for up to 3 weeks, whereas scores of WOF and levels of TBARS increased rapidly during retail storage for up to 3 days. The development of WOF during retail storage was avoided when the product was vacuum-packed or gas-packed. Only insignificant microbiological changes were observed during bulk storage of the product or during the subsequent retail storage. Received: 8 October 1997 / Revised version: 19 December 1997     

Effect of pasture versus indoor feeding regimes on the yield,composition, ripening and sensory characteristics of Maasdam cheese

Maasdam cheese was manufactured from standardized milk derived from each of three feeding systems: grass (GRA), grass and clover pasture (CLO), and indoor feeding of total mixed ration (TMR). Pasture‐derived cheeses had significantly lower L* (whiteness) and higher b* values (yellowness) compared to TMR‐derived cheeses. Acetate levels were significantly lower in CLO and butyrate levels significantly higher in TMR compared to the other cheeses. Grass‐fed cheese had significantly higher scores for smooth texture, ivory colour and shiny appearance compared to TMR. The influence of feed type was minimal on cheese yield, composition and on glycolysis, lipolysis and proteolysis during ripening.     

Comparison of heating methods and the use of different tissues for sensory assessment of abnormal odours (boar taint) in pig meat

Five heating methods (microwave, hotwire, boiling at 25 °C and 75 °C and melting) were used to generate cooking odours from backfat of entire male pigs and a 'composite' sample consisting of fat and muscle from the head along with salivary glands. The methods elicited significantly different scores for odours from 4 groups of 10 samples differing in their concentrations and ratios of skatole and androstenone. The odours (pork odour, abnormal odour, skatole odour and androstenone odour) were assessed by 3 experienced assessors. Correlations between skatole and androstenone concentrations and abnormal odour score in backfat were higher for skatole, suggesting it is the more important boar taint compound. In the composite sample, androstenone concentration was much higher than in backfat and androstenone was a more important contributor to boar taint. The microwave, hotwire and boiling (75 °C) methods produced the clearest separation between samples and the microwave method was considered the most suitable for on-line use.     

Changes in the texture,physicochemical properties and volatile compound profiles of fresh Kashar cheese (<90 days) during ripening

In this study, four different fresh Kashar cheese samples were ripened for 90 days. The physicochemical properties, texture attributes, fatty acid composition and volatile compound profiles of the samples were measured every 30 days of ripening. The texture properties of the cheese samples were significantly affected by the duration of the ripening period. The results of this study highlighted that texture parameters as a function of ripening period should be considered for both fresh and aged Kashar cheeses to determine the ripening period as they are very important for consumer acceptability and consumption of the end product.     

Changes of lactose, lactic acid, and acetic acid contents in Serra cheese during ripening

 Changes in the quantities of lactose, lactic acid and acetic acid in Serra cheese were monitored using a triplicate two-way factorial design over a ripening period of 35 days (sampling at 0, 7, 21 and 35 days) throughout the cheesemaking season (sampling in November, February and June). The amount of lactose in total solids of cheese (TS) decreased slowly from 6.17% to 0.21% (w/w_TS) as ripening time elapsed. As a result of sugar metabolism, the lactic acid content increased from 0.07% at day 0 to 2.10% (w/w_TS) by 35 days, whereas the acetic acid content increased from 0.00% to 0.24% (w/w_TS) during the first week. The lactose content was statistically correlated with the lactic acid content but not with the acetic acid content. Received: 18 November 1996