Abstract:

Hardness is one of the most important food texture attributes. Reference sample for sensory evaluation is the
foundation for understanding the specific sensory attribute and evaluating its intensity. At present, the reference samples for
food texture sensory evaluation in international standard and Chinese standard are mainly based on the Western diet. Most of
them are difficult to obtain and also unfamiliar to Chinese. Therefore, it is necessary to establish Chinese reference samples
for food texture to satisfy Chinese conditions. A rapid method for screening reference sample was developed in this paper
through a case study of establishing hardness references. The method is based on statistical analysis of the sample hardness
data from texture analyzer (TPA) testing. Cluster analysis, principal component analysis and analysis of variance were used
to choose the samples which meet the general requirements for sensory attribute references, such as typical, representative
and stable requirements. A descriptive analysis panel consisting of 10 assessors was selected to evaluate the sensory intensity
of harness by using 15 cm linear scale. Totally 9 reference samples for food hardness intensity were finally selected out of
16 categories consisting of more than 100 food products including Baiyu tofu, Labixiaoxin jelly, Jinluo sausage, Henghui
egg curd, Beijing Yiming canned chufa, Huiyi crisp peanut, almond produced by China Oil and Foodstuffs Corporation
(COFCO), Sugus, and crystal sugar from Ershang Group with hardness intensity of 1.0, 2.4, 4.3, 5.6, 7.4, 9.8, 10.8, 12.2
and 14.0, respectively. Moreover, there existed a linear relationship between the natural logarithm of sensory intensity value
and physical hardness data from TPA testing (y = 0.46x－2.424, R2 = 0.977), which was consistent with the psychophysical
power law. The established hardness reference samples not only provide a unified “ruler” for sensory evaluation of food
hardness in China, but also provide a guide to establish reference samples for other sensory attributes.

Key words: hardness, texture, reference sample, sensory analysis, psychophysical law