No abstract

The effect of hydroxylamine (NH2OH), p‐aminobenzoic acid (PABA) and p‐aminosalicylic acid (PASA) on the spectrum of the final product (s) formed when o‐dihydroxy‐ and trihydroxyphenols were oxidized by tyrosinase was examined. New pigmented product(s), probably oximes, were formed by the interaction of NH2OH with the o‐quinones of 4‐methyl catechol, 3,4‐dihydroxyphenylacetic acid (DOPAC) and 3,4‐dihydroxyphenylpropionic acid (3,4‐DPPA) but not with the o‐quinones of catechol or protocatechuic acid. Interaction of PABA or PASA with the o‐quinones of catechol, 4‐methyl catechol, protocatechuic acid, DOPAC and 3,4‐DPPA also yielded pigmented oximes. The interaction of the o‐quinones of trihydroxyphenols with NH2OH, PABA or PASA had little effect on the spectrum of the final product (s), suggesting that oximes are not formed in these reactions.

No abstract

Heating `Golden Delicious' apples (Malus domestica Borkh.) for 4 days at 38C or pressure-infiltrating them with a 4% CaCl2 solution reduced decay and maintained fruit firmness during 6 months of storage at 0C. Heating reduced decay caused by Penicillium expansum Link ex Thorn by ≈30%, while pressure infiltration with CaCl2 reduced decay by >60%. Pressure infiltration with CaCl2 after heating reduced decay by ≈40%. Pressure infiltration maintained firmness best (>84 N), as measured with a manually driven electronic fruit-firmness probe, followed by heat and CaCl2 (76 N), heat alone (71 N), and no treatment (control) (60 N). Force vs. deformation (FD) curves from a puncture test with a fruit-firmness probe mounted in a universal testing machine showed that fruit heated before storage were firmer than all nonheated fruit, except those pressure-infiltrated with 4% CaCl2. However, FD curves also showed that apples pressure-infiltrated with 4% CaCl2 differed quantitatively from apples in all other treatments, including those heated.

No abstract