column_name is a vector, so strcmp(column_name,'Corn') is a vector (of class logical), so when you do:
if match_corn == 1
that condition will be considered true only if all elements of match_corn are true, i.e., all elements of column_name are 'Corn'.
Instead, you want to count the number of non-zero elements of match_corn, which you can do with nnz:
column_name = new_data(:,9);
match_corn = strcmp(column_name,'Corn');
match_rice = strcmp(column_name,'Rice');
match_flour = strcmp(column_name,'Flour');
count_corn = nnz(match_corn);
set(handles.edit3,'String',count_corn);
count_rice = nnz(match_rice);
set(handles.edit4,'String',count_rice);
count_flour = nnz(match_flour);
set(handles.edit5,'String',count_flour);
