# Rheology-Based Classification of Foods for the Elderly by Machine Learning Analysis
## 2 Materials and Methods
### Rheological Measurements  
Different instrumental rheology measurements were made using a texture analyzer (TA.XT plus, Stable Micro Systems, Surrey, UK) equipped with a 500 N load cell. First, mung-bean starch gels with different degrees of hardness were subjected to four different measurements, including UDF, cutting-shear, puncture, and compression tests, and the detailed experimental conditions were as follows. All of the texture measurements were made in triplicate, and the experimental results were expressed as mean \(\pm\) standard deviation.  
UDF test: based on the methods of [PERSON] et al. (2018) and Japan Care Food Conference (2018), the UDF test was carried out. First, a sample was loaded in a UDF container (40 mm in diameter and 25 mm in height) to have a height of 15 mm. Thereafter, a cylindrical probe (diameter 20 mm, height 35 mm) was compressed to a clearance of 5 mm from the bottom of the vessel at a crosshead speed of 600 mm/min.  
Cutting-shear test: according to the method of [PERSON] (2018), a sample was loaded on a plate with a central hole (width 55 mm, length 3 mm). Thereafter, a blade probe (width 50 mm, height 60 mm, thickness 0.5 mm) was lowered at a crosshead speed of 100 mm/min until it passed through the sample.  
Puncture test: a sample was loaded on a plate with a central hole (10 mm), and a rod probe (diameter 5 mm) was lowered at a crosshead speed of 100 mm/min until it passed through the sample.  
Compression test: a compression test was carried out based on the method of [PERSON] et al. (2018). A sample (diameter 20 mm, height 15 mm) smaller than the probe size was loaded on a plate. Thereafter, a disk probe (diameter 50 mm, height 10 mm) was lowered at a crosshead speed of 100 mm/min at 66.7% strain.  
\begin{table}
\begin{tabular}{c c} \hline
**Classification by Korean Food Code** & **Samples** \\ \hline Soybean Sauces & Gochujang (C) Cheiljedang), SSamjang (C) Cheiljedang) \\ \hline Salted or Boiled Foods & Pickled radish (llga, Sejong-si, Korea) \\ \hline Processed Agricultural Products & White mushroom (Moring Farm, Gyeongsang, Korea) \\ \hline Processed Meat and Packaged Meat & Smoked ham (Samhoham, Gyeong-gi, Korea), Sausage (Lotte), Frank sausage (Hansung, Gyeongsang, Korea), Chicken steak (Farmsco, Gyeong-gi, Korea), Brown \\  & rice chicken steak (Haetsal Food System, Gyeong-gi, Korea), Hamburg steak (C) \\  & Cheiljedang), Hamburg steak (Ottogi) \\ \hline Dairy Products & Mozzarella cheese (Saputo, Montreal, Canada), Monterey jack cheese (Great lakes \\  & cheese, Hiram, Georgia, USA), Cheddar cheese (Great lakes cheese) \\ \hline Fishery Products & Fish cake bar (Sajo, Gyeong-gi, Korea) \\ \hline Instant Foods & Instant rice (C) Cheiljedang), Instant abalone porridge (C) Cheiljedang) \\ \hline \end{tabular}
\end{table}
Table 1: Cont.  
For all of the instrumental methods, the plots of force versus time were obtained, and the maximum peak values were then recorded as hardness. After the four instrumental measurements were compared, the UDF and puncture tests were selected and further compared to each other. Specifically, a total of 59 food samples (25 gels + 34 commercial products in Table 1)s were subjected to both UDF and puncture tests under the conditions mentioned above, followed by the tensorflow-based machine learning analysis.