CRISPNESS AND CRUNCHINESS JUDGMENT OF APPLES BASED ON CONTACT ACOUSTIC EMISSION

Contact acoustic emission (AE) measurement, together with a puncture test, were used to evaluate the crispness and crunchiness of three apple cultivars. A storage program was used to induce changes in apple crispness and crunchiness. The instrumental measurements were compared with the results of sensory evaluation.
It was found that crispness and crunchiness could be evaluated instrumentally by measuring firmness, AE events, mean AE amplitude or the product of AE events and mean AE amplitude. For one cultivar, however, firmness was not correlated with any sensory attribute. Generally, the best correlation with sensory attributes was found for the exponential value of AE events. Contact AE allows the measurement of sensory crispness or crunchiness for a given apple cultivar or independently for any apple cultivar. Contact AE can be considered as a useful method for the evaluation of sound properties of wet-crisp foods.

PRACTICAL APPLICATIONS

Contact acoustic emission method can be used for instrumental evaluation of crispness and crunchiness of apples. The method allows more accurate evaluation of these attributes than firmness measurement. There is a chance to extend the application to other wet-crisp foods and to use the method together with other destructive tests, like texture profile analysis or single edge notched bend.     

PHYSICAL AND SENSORY EVALUATION OF CORNFLAKES CRISPNESS

Three compression systems were used to study the mechanical behavior of cereal flakes of 13 commercial cornflakes brands that were also evaluated by sensory analysis. A Kramer cell, on an Instron testing machine, allowed to simultaneously record force in the range 0–5 kN and sound in the frequency domain 0–22 kHz during the crushing of 20 mm thick beds of cereal flakes tested in bulk. It was shown to be the most reliable and efficient method for discrimination. Acoustic emission has been shown to correlate with crispness perception. Uncrispy‐perceived products emitted signals with lower average amplitude and higher peaks, at low frequencies – less than 3 kHz – and opposed a high mechanical resistance to compression. On the opposite, the crispiest flakes emitted sounds with larger average amplitude, fewer high peaks and uniformly distributed in the frequency domain with a moderated mechanical resistance. Links between texture perception and structure were improved and results validated the developed system, which may be used for quality evaluation of particle solid foam foods.     

Sensory Crispness of Crispy Rolls: Effect of Formulation, Storage Conditions, and Water Distribution in the Crust

ABSTRACT:  Crispness is an important sensory quality parameter that strongly influences the acceptability of cellular solid foods such as the crust of many types of breads. Crispness of the bread crust depends particularly on its water content. In this study, the relationship between sensory crispness of crispy rolls and the average water content of the crust was studied for different bread formulations (control, amylase, glucose-oxidase, and protease) and storage conditions (40% and 80% RH). From the different formulations used, only protease treatment increased the crispness of the crust and its retention at both storage conditions. The positive effect of the protease treatment was due to a lower water content of the crust of these breads compared to the other formulations. The relationship between sensory attributes, formulation, and storage conditions was found to be dominated by the dependence on storage conditions. When combining data for low and high humidity storage it showed that crusts with equal water contents could exhibit different scores for crispness. The results led to the hypothesis that a gradient of water content exists within the crust. At high humidity, the crust will take up water from both crumb and environment and a relative smaller gradient of water will exist within the crust. At low humidity on the other hand, the crust will take up water from the crumb only, resulting in a larger gradient of water within the crust.     

食品脆度评价方法研究进展

脆度是食品质地评价中的重要属性,也是消费者非常关注的食品质量指标之一。作者分析总结了近几十年来力学评价、声音信号评价以及感官评价等食品脆度评价方法的研究进展。结论如下：1）力学评价具有较高的准确度和稳定性,但不同模式下结果也会存在不同,单独用此方法评价食品脆度不够准确;2）声音信号评价能更客观地对脆性食品产生的声音信号进行分析、评价,但也存在信号采集不稳定、易受外界噪声干扰等问题,若结合力学评价、感官评价,将能更好地评价食品脆度;3）感官评价直观、简便,但对评价人员要求高且主观性较强,容易出现偏爱型误差,需要更科学的客观评价方法进行辅助评价。该文可以为探寻最佳、通用的食品脆度评价方法提供一定线索。     

INFLUENCE OF APPEARANCE ON THE ASSESSMENT OF AROMA IN BORDEAUX WINES BY TRAINED ASSESSORS

Similarity-scaling approaches and INDSCAL analysis were used to survey 1976 Bordeaux wines presented to trained assessors in four ways: (i) in clear (colourless) glasses with instructions to assess both appearance and aroma attributes; (ii) in clear glasses with instruction to assess aroma, ignoring visual cues; (iii) in clear glasses but under red illumination; and (iv) in coloured glasses, with instruction to assess similarities using aroma only. The results indicated that when instructed to ignore appearance, assessors as a whole succeeded in doing so, providing similar information to that which was obtained in red glasses or under red illumination. When differences in wines are assessed using both appearance and aroma, there is evidence to indicate that some aroma attributes are being assessed differently from when the assessors could not see the wine or were instructed to ignore its appearance.     

A METHOD FOR DIRECT ASSESSMENT OF MALT MODIFICATION

A new test is described which directly determines the status of modification of individual malt corns. Longitudinally-cut half sections of malt are extracted (‘mashed’) in water at 65°C. The enzymically modified regions of the endosperms are dissolved away whilst the unmodified areas are retained in the cut grains.     

ACOUSTIC EMISSION, FRACTURE BEHAVIOR AND MORPHOLOGY OF DRY CRISPY FOODS: A DISCUSSION ARTICLE

This article describes sound properties that are special for crispy foods and relates them to general knowledge on the acoustic emission and mechanical properties of fracturing materials. From properties like the occurrence of sound, the sound energy, the duration of single sound waves, the time interval between the sound pulses and from the force drops involved, it was possible to calculate the morphological constraints for dry, crispy cellular foods. We present data for the minimum and maximum sizes of the pores and of the sizes of the solid material element surrounding them. The loss of crispness in foods caused by aging under deteriorating circumstances was found not to be caused by changes in the type of elements that fracture.     

ACETIC ORCEIN STAINING TEST FOR ASSESSMENT OF PREGERMINATION IN BARLEY

The embryo of dehusked pregerminated barley will stain red with a dilute solution of acetic orcein. This staining test has been used to assess the degree of pregermination of barley samples.     

物性分析仪在食品质构测定方面的应用

质地特性是食品极其重要的品质因素。一般采用的感官评定方法主观因素偏重，而物性分析仪所反映的主要是与力学特性有关的食品质地特性，其结果具有较高的灵敏性与客观性，故其使用越来越广泛。本文综述了物性分析仪的原理及其在小麦粉制品、肉制品、水产品和乳制品中的应用，以及存在的问题与展望。     

A COMPUTER CONTROLLED MICROMALTER FOR ASSESSMENT OF THE MALTING POTENTIAL OF BARLEY CROSSBREDS

An automatic, computer-controlled micromalter with several advantages over current designs has been constructed. All operations are carried out in the one cabinet, and it is not necessary to intervene at any point during the malting process. The sample containers were constructed so that mechanical deculming of groups of ten large or fifteen small samples could be carried out in ten minutes. Initially, the capacity of the micro malter was 40 × 100 gm or 70 × 60 gm samples. These capacities were doubled by the use of longditudinal dividers slid into each canister, making the apparatus suitable for screening of samples submitted from the early generations of a breeding programme. The results obtained by malting 36 large and 60 small samples of the same variety; six replicates of six varieties; and subsamples of a bulk of a single variety in 37 subsequent runs all indicated that the instrument provided satisfactory separation and ranking between samples of differing malting qualities and grouped samples of similar malting qualities together.