Application of mid-infrared spectroscopy to the prediction of maturity and sensory texture attributes of cheddar cheese.

The objective of this study was to determine the potential of mid-infrared spectroscopy in conjunction with partial least squares (PLS) regression to predict various quality parameters in cheddar cheese. Cheddar cheeses (n= 24) were manufactured and stored at 8 degrees C for 12 mo. Mid-infrared spectra (640 to 4000/cm) were recorded after 4, 6, 9, and 12 mo storage. At 4, 6, and 9 mo, the water-soluble nitrogen (WSN) content of the samples was determined and the samples were also evaluated for 11 sensory texture attributes using descriptive sensory analysis. The mid-infrared spectra were subjected to a number of pretreatments, and predictive models were developed for all parameters. Age was predicted using scatter-corrected, 1st derivative spectra with a root mean square error of cross-validation (RMSECV) of 1 mo, while WSN was predicted using 1st derivative spectra (RMSECV = 2.6%). The sensory texture attributes most successfully predicted were rubbery, crumbly, chewy, and massforming. These attributes were modeled using 2nd derivative spectra and had corresponding RMSECV values in the range of 2.5 to 4.2 on a scale of 0 to 100. It was concluded that mid-infrared spectroscopy has the potential to predict age, WSN, and several sensory texture attributes of cheddar cheese.

Evaluating mid-infrared spectroscopy as a new technique for predicting sensory texture attributes of processed cheese.

The objective of this study was to investigate the potential application of mid-infrared spectroscopy for determination of selected sensory attributes in a range of experimentally manufactured processed cheese samples. This study also evaluates mid-infrared spectroscopy against other recently proposed techniques for predicting sensory texture attributes. Processed cheeses (n = 32) of varying compositions were manufactured on a pilot scale. After 2 and 4 wk of storage at 4 degrees C, mid-infrared spectra (640 to 4,000 cm(-1)) were recorded and samples were scored on a scale of 0 to 100 for 9 attributes using descriptive sensory analysis. Models were developed by partial least squares regression using raw and pretreated spectra. The mouth-coating and mass-forming models were improved by using a reduced spectral range (930 to 1,767 cm(-1)). The remaining attributes were most successfully modeled using a combined range (930 to 1,767 cm(-1) and 2,839 to 4,000 cm(-1)). The root mean square errors of cross-validation for the models were 7.4 (firmness; range 65.3), 4.6 (rubbery; range 41.7), 7.1 (creamy; range 60.9), 5.1 (chewy; range 43.3), 5.2 (mouth-coating; range 37.4), 5.3 (fragmentable; range 51.0), 7.4 (melting; range 69.3), and 3.1 (mass-forming; range 23.6). These models had a good practical utility. Model accuracy ranged from approximate quantitative predictions to excellent predictions (range error ratio = 9.6). In general, the models compared favorably with previously reported instrumental texture models and near-infrared models, although the creamy, chewy, and melting models were slightly weaker than the previously reported near-infrared models. We concluded that mid-infrared spectroscopy could be successfully used for the nondestructive and objective assessment of processed cheese sensory quality.

Composition, sensory and shelf life stability analyses of Longissimus dorsi muscle from steers reared under organic and conventional production systems.

In recent years the demand for organically grown food has increased. In this study, organic (O, n=6) and conventionally (C, n=6) reared steers aged between 18 and 24 months were slaughtered during the month of September 2002. Four days post-slaughter, the Longissimus dorsi (LD) muscle was excised from the left side of each carcass. All muscles were vacuum packed and aged in a chill for a further seven days. Steaks were cut from each sample, and from these, lean meat was removed, blended and compositional analysis was carried out. O samples were significantly higher (P>0.05) in fat content and therefore were significantly (P>0.05) lower in moisture content than C samples. No significant differences were observed between C and O samples for protein, ash, ß-carotene, α-tocopherol or retinol. There was also no significant difference in fatty acid content between C and O samples. Colour stability and fat oxidative stability of samples were also measured, while stored under retail conditions. Samples were packed using both modified atmosphere packaging (MAP) and by overwrapping with cling film. MAP C samples had the best colour stability while overwrapped C samples had the best lipid stability. Therefore, colour and lipid stability of beef samples were influenced by sample composition and packaging format used, which resulted in C samples outperforming O samples with respect to shelf life stability.

The spacing effect in short-term motor memory.

A study of the spacing effect was conducted within a short-term motor memory framework. In Experiment 1 subjects received one or six repetitions of a discrete linear movement at intervals of 5 or 60 sec, and with a constant retention interval of 30 sec. The performance over 10 trials was analyzed in terms of algebraic, absolute, and variable error. The facilitation associated with longer intervals found in verbal retention situations was obtained in the present study for algebraic error only. The results were discussed in terms of the several hypotheses offered by Hintzman (1974), and a mechanism for the operation of differential attention was suggested. Inconsistencies with previous data were discussed. Experiments 2 and 3 addressed some unresolved issues from Experiment 1 and additional support for the differential-attention hypothesis was obtained.