Propionic acid ($CH_3CH_2COOH$) is a short-chain saturated monocarboxylic fatty acid consisting of only 3 carbons ($C_3$). It is widely known for selectively inhibiting molds and rope-forming bacteria while having minimal inhibitory activity against baker's yeast (Saccharomyces cerevisiae), making it ideal for bread preservation. Therefore, calling it a 'long chain fatty acid' is factually false (making statement 3 the correct answer).

Option analysis:

• It is effective against molds: True, it is a premier antimycotic food preservative.
• It affects cell membrane permeability: True, un-ionized acid dissipates proton gradients across microbial membranes.
• It is a long chain fatty acid: Not true (false statement), propionic acid is a 3-carbon short-chain fatty acid.
• It is less effective against yeast and bacteria: True, allowing yeast fermentation to continue in doughs.

Aspartame is an intense non-nutritive artificial sweetener approximately $180 - 200$ times sweeter than sucrose. Chemically, it is the methyl ester of the dipeptide formed from two natural amino acids: L-aspartic acid and L-phenylalanine (specifically, N-(L-$lpha$-aspartyl)-L-phenylalanine 1-methyl ester).

Option analysis:

• Proline and valine: Incorrect amino acids.
• Histidine and proline: Incorrect amino acids.
• Aspartic acid and phenylalanine: Correct, the two constituent amino acids of aspartame.
• Arginine and tryptophan: Incorrect amino acids.

Biogenic amines are classified by chemical structure into aliphatic, aromatic, and heterocyclic amines. Putrescine (1,4-diaminobutane, $NH_2(CH_2)_4NH_2$), cadaverine, spermine, and spermidine are aliphatic biogenic amines lacking aromatic rings. Tyramine is an aromatic amine, while tryptamine and histamine (derived from histidine) are heterocyclic amines.

Option analysis:

• Putrescine: Correct, aliphatic diamine formed by decarboxylation of ornithine.
• Tyramine: Aromatic biogenic amine formed from tyrosine.
• Histidine: An amino acid containing an imidazole heterocyclic ring, not a biogenic amine itself.
• Tryptamine: Heterocyclic indoleamine formed by decarboxylation of tryptophan.

Carrageenans are a family of linear sulfated galactans extracted from red edible seaweeds (Rhodophyceae), principally species of Gigartina, Chondrus crispus (Irish moss), Eucheuma, and Kappaphycus. They are widely utilized in the food industry as gelling, thickening, and stabilizing hydrocolloids.

Option analysis:

• Caulerpa: Green seaweed (Chlorophyceae), not a source of carrageenan.
• Gigartina: Correct, red seaweed belonging to Rhodophyceae, a principal industrial source of carrageenan.
• Sargassum: Brown seaweed (Phaeophyceae), source of alginates, not carrageenan.
• Monostroma: Green seaweed, consumed as nori/aosa, not a carrageenan producer.