Texture evolution of "Amaretti" cookies during storage

The results of a study on texture evolution during 35 days of storage of ldquoamarettirdquo, a typical Italian cookie, packaged in two different ways are reported. Amaretti cookies were wrapped in polyvinylchloride (PVC) film or aluminium foil (ALL), to simulate two different permeability conditions and stored at controlled temperature and humidity. Evolution of texture (such as hardness) and aw were tested instrumentally by a texture analyser and a hygrometer, respectively. Texture was assessed by a cut and puncturing test. Indices for hardening were the area under the curve (N mm) and gradient (N/mm) for the puncturing test and maximum force (N) for the cut test. Both textural tests showed significantly higher hardening of PVC cookies, compared to the ALL cookies. The latter retained good sensorial properties at the end of the storage period, although their internal structure changed from soft and moist to mealy, while the PVC cookies were no longer edible only 10 days after baking. aw values decreased and increased in PVC and ALL lots, respectively. The results suggest that hardening may be explained by water loss in PVC and moisture redistribution in ALL

Effects of additives and ingredient sizing on the shelf-life of "Amaretti" cookies

Cookies are characterised by moisture and water activity (aw) higher than 7% and 0.5, respectively. Cookies have the capacity of bending after baking, when they are fresh, unlike biscuits that break when bent. Hardening is the main cause of quality deterioration of cookies, which change from soft and pliable to firm and crumbly within a few days or even hours after baking. Little research has been done on cookies. "Amaretti" are typical Italian cookies, found in several regions of Italy. Freshly baked "Amaretti" are soft and delicious but undergo severe hardening after seven to ten days, thus limiting the shelf-life, so Amaretti can be marketed only locally. In the present work several attempts have been made in order to extend the shelf-life of Sardinian "Amaretti". In particular, changes to the formulation and to the almond particle size were made. The traditional formulation was, in fact, modified by adding rice starch (thickening agent) or mono-diglyceride of fatty acids (emulsifier). Almonds were grinded to a particle size lower or higher than 1 mm. Amaretti baked with the traditional recipe were used as control. After baking and cooling cookies were wrapped with an aluminium foil and stored at controlled temperature and humidity. Evolution of texture (as hardness) and aw during storage were followed instrumentally by a texture analyser and a hygrometer, respectively

A study on relationships between durum wheat semolina properties, technological mixing parameters and the properties of dough after mixing

Partial least square regression analysis was used to study the correlation between X variables (semolina quality, hydration level and mixing time) and Y variables, which were, in a first model, dough consistency during mixing, and, in a second model, dough properties after mixing (strength, elasticity, density) and leavening (maximum volume). The first model showed a predictive residual sum of squares (PRESS) of 2.98 and a predictive R2 (Q2) of 0.92, and highlighted the key role of hydration and mixing time ondough consistency. The second model had the best PRESS (8.25) and Q2 (0.94) values for dough volume and indicated that the volume increased with increasing mixing time until the dough consistency decreased of 20–30%. Dough volume was primarily affected by hydration. The model indicated that maximum volume after leavening, corresponding to optimum mixing time, was obtained with a soft and elastic dough, with a low-density valu

Bioconversion of ovine scotta into lactic acid with pure and mixed cultures of lactic acid bacteria.

Abstract Scotta is the main by-product in the making of ricotta cheese. It is widely produced in southern Europe and particularly in Italy where it represents a serious environmental pollutant due to its high lactose content. With the aim of evaluating whether scotta bioconversion into lactic acid can be considered as an alternative to its disposal, besides providing it with an added value, here the growth, fermentative performances, and lactic acid productions of pure and mixed cultures of Lactobacillus casei, Lactobacillus helveticus, and Streptococcus thermophilus were evaluated on ovine scotta-based media, without and with the addition of nutritional supplements. The outcomes indicate that ovine scotta can be utilized for the biotechnological production of lactic acid with yields up to 92%, comparable to those obtained on cheese-whey. Indeed, the addition of nutritional supplements generally improves the fermentative performances of lactic acid bacteria leading to about 2 g l−1 h−1 of lactic acid. Moreover, the use of mixed cultures for scotta bioconversion reduces the need for nutritional supplements, with no detrimental effects on the productive parameters compared to pure cultures. Finally, by using L. casei and S. thermophilus in pure and mixed cultures, up to 99% optically pure l-lactic acid can be obtained

Effectiveness of active and modified atmosphere packaging on the shelf-life extension of a cheese tart

The shelflife extension by MAP and AP of a typical cheese tart was studied. Baked tarts were packaged inside barrier to gas trays and wrapped with a barrier to gas and water film. Four batches were prepared: 1) Control; 2) MAP with different N2/CO2 ratios (70/30 and 20/80); 3) Trays with an iron oxide-based oxygen absorber. Tarts were stored at 20°C and sampled for analysis at 0,7, 14,27,35 and 48 days. Determinations inc1uded microbioIogical analyses (total bacterial count, moulds, yeast and staphylococci), chemical-physical parameters (pH, water activity and dry matter), gas changes (CO2, O2 and N2) inside MAP and AP trays, texture evolution and sensory analysis at our laboratories. AP allowed a shelf life of 48 days, MAP shelf lives were of 14 and 34 days for 70/30 and (20/80), respectiveIy, while controI tarts spoiled after only 7 days

Rheological properties and baking quality of commercial durum wheat meals used to make flat crispy bread

Four commercial semolinas and four low-grade semolinas (LGS) samples were used in this study to make flat crispy bread (Carasau). The meals, doughs, and bread were compared with respect to a set of physical, chemical, and textural characteristics, and the bread evaluated by a trained sensory panel. LGSs had a higher extraction rate (higher ash content), finer granularity, and a higher damaged starch content than semolinas. The study revealed the key role of dry gluten content in determining hydration capacity of the dough, whereas damaged starch affected water absorption only in semolina samples. Gluten index and the ratio of gluten tenacity to extensibility (alveograph P/L) were significantly correlated with the weight of the dough discs following sheeting and molding. The panelists gave the highest quality score to the bread with the highest values of crackling and hardness. Textural and sensory attributes were both correlated with one another, and with gluten strength and tenacity, but not with the gluten content of the meal, which only affected final moisture content of the bread. Meal samples with a more tenacious and elastic gluten were more suited to produce flat crispy breads. The yellowness of durum wheat bread could not be predicted by measuring the color of the meal with a reflectance method

The Effects of Ovine Whey Powders on Durum Wheat-Based Doughs

Two types of ovine whey powder, with different protein content, were added at increasing substitution rates to two types of semolina, one with strong and tenacious gluten and the other with weak and sticky gluten. For each dough the optimum mixing time and hydration level were calculated using the consistograph. The whey powder negatively affected the leavening volume of all doughs, at all percentages except the lowest one (5%), mainly because of its effects on the elastic component of gluten as measured with a stress relaxation test. Differences of the secondary structure of gluten proteins among samples were investigated by analyzing the amide I band in the Fourier transform infrared spectra of the dough. Weak and strong semolina showed a different relative percentage of α-helix, random coil, and β-sheet structures. The longer mixing times for dough formation when using semolina with strong gluten led to an increase in α-helices and random coils, which caused a worse leavening performance than the weak-gluten semolina

Random amplified polymorphic DNA and amplified ribosomal DNA spacer polymorphism: powerful methods to differentiate <i>Streptococcus thermophilus</i> strains

Streptococci from different collections and dairy materials were characterized by conventional and molecular methods. After amplification of the 16S–23S rDNA spacer region, all the strains referable to the genus Streptococcus exhibited a single polymerase chain reaction (PCR) product, allowing their differentiation from enterococci. Cleaving this PCR product with Hae III, two different restriction patterns could be observed, allowing Streptococcus salivarius DSM 20560T, Strep. thermophilus NCDO 822 and two strains of Streptococcus spp. to be gathered in one group and all the other strains in another. In order to achieve strain typing, all the cultures were investigated by random amplified polymorphic DNA (RAPD)-PCR analysis employing two selected primers. The results were treated by cluster analysis, appearing significantly consistent with both the taxonomic position and the origin of the strains. Pulsed-field gel electrophoresis (PFGE) of Sma I digests of the genomic DNA from 11 representative strains with decreasing levels of RAPD similarity allowed their diversity to be confirmed, even though RAPD-PCR proved to be less discriminating than PFGE analysis. The results are discussed with reference to the capability of the analytical procedures used to aid both identification and strain typing of streptococci, as well as the taxonomic structure of the species Strep. thermophilus

Effects of the fermentation process on gas-cell size two-dimensional distribution and rheological characteristics of durum-wheat-based doughs

In this study, the effects of baker's yeast and sourdough fermentation on gas-cell size distribution and height of leavened doughs were evaluated in eight durum-wheat-based doughs of different strengths. Furthermore, the chemical and rheological properties of the doughs were analyzed to determine their effects on the leavening process. The gas-cell size distribution was modeled by a log-normal distribution across the full range of gas-cell sizes (10− 4 to 102 mm2), and by a power-law distribution for the large gas cells. The power law α exponent analysis of variance showed that α distinguished between the two empirical distributions, which indicated that there were more larger cells in the sourdough samples than in the baker's yeast samples. The distribution of the small-to-medium gas cells was the same for the two processes, as indicated by the log-normal parameters. The leavened dough height was generally higher for the baker's yeast dough samples, compared to the sourdough samples, except in the case of samples with very strong and elastic gluten

Quality changes of fresh filled pasta during storage: influence of modified atmosphere packaging on microbial growth and sensory properties

This study evaluated the shelf life of fresh pasta filled with cheese subjected to modified atmosphere packaging (MAP) or air packaging (AP). After a pasteurization treatment, fresh pasta was packaged under a 50/50 N2/CO2 ratio or in air (air batch). Changes in microbial growth, in-package gas composition, chemical—physical parameters and sensory attributes were monitored for 42 days at 4 °C. The pasteurization treatment resulted in suitable microbiological reduction. MAP allowed a mold-free shelf life of the fresh filled pasta of 42 days, whereas air-packaged samples got spoilt between 7 and 14 days. The hurdle approach used (MAP and low storage temperature) prevented the growth of pathogens and alterative microorganisms. MAP samples maintained a high microbiological standard throughout the storage period. The panel judged MAP fresh pasta above the acceptability threshold throughout the shelf life