blue (citrate) tube
Blue top tube which contains citrate.
Bacteria and Salmonella grow in warm conditions. Too hot or cold will kill them and so a warm, wet environment is perfect for them to grow.
If bacterium cannot use glucose the fermentation tube will stay the same color. Gas may also occur inside the fermentation tube.
Black top (sodium citrate tube) or light blue tube. They both contain sodium citrate. I failed this question on my final, I knew a black top tube is used but it was not given to me as a choice. I did not think hard enough to come to the conclusion that a light blue tube would be another option.
Guessing you're asking about color coded vacutainers, since otherwise I can't make any sense of the question. Light blue is usually the color code for a tube with sodium citrate.
Food poisoning doesn't grow on food. It is from bacteria that grows on it.
A centrifuge tube would be useful, but a regular test tube will suffice.
elevated glucose value
Sodium Citrate, the same as Light Blue top tubes.
The only way the greens could have Salmonella is if the Salmonella was already in the greens when the package was sealed - or if the packaging itself was contaminated. Salmonella can grow on the plant juices.
Salmonella is a type of bacteria. It requires a pH of 4.4 to 9.0 (prefers 6.5 to 7.5) to grow successfully.