With the help of a colleague, I have answered my own question in a rough manner. It increases the computing time by a decent bit. I would like to hear more optimized suggestions if any exist before marking anything as solved. Here is the code:
for i= 1:length(table_heightsN)
ArrayN{i,1}.Timestamp = zeros(table_heightsN(i),1);
[row,col] = size(ArrayN{i,1});
for j=1:row
FrameNum = ArrayN{i,1}.ImageNumber(j);
FrameNum = FrameNum+1;
ind1 = find(TT.Index == FrameNum);
ArrayN{i,1}.Timestamp(j) = sum(sscanf(char(TT.Time_m_s_ms_(ind1)),'%f:%f').*[60;1]);
end
end