Nonenzymatic browning of single strength orange juice and synthetic orange drinks containing 10% (v/v) orange juice has been studied under aerobic and anaerobic conditions. The juice and drinks were aseptically packaged into two types of flexible film (retort pouch and polyethylene Whirl-Park) and stored at 20 wk at 24°C. Ascorbic acid retention was affected by the processing itself, the concentration of added amino acids, and by the packaging material. The effect of amino acids on browning was found to be linear with concentration and was more pronounced in the presence of high levels of ascorbic acid.

Flavor and color concentrates were prepared by a vacuum distillation process from cold pressed Valencia and midseason orange oils and were analyzed quantitatively by gas chromatography. Twentyfive major and minor constituents were identified by mass spectrometry. The influence of the concentration process on oxygenated flavor compounds, primarily aldehydes and alcohols, was evaluated. Aldehydes and color values were determined by chemical and spectrophotometric methods. When compared with midseason orange oils, 25-35s higher concentration of oxygenated flavor compounds and of total aldehydes were found in Valencia orange oils. Midseason oils had 20-30s higher color values when compared with Valencia oils. Cold pressed oils concentrated to 25-fold had an increase in color value of 20-fold, while the concentration of oxygenated flavor compounds increased about 10 times.

Browning and changes in the composition of sliced and whole carambola (Averrhoa carambola L.) fruit during storage were investigated. Susceptibility to browning after slicing, packaging and storage for 4 wk at 4.4ЊC varied considerably between four cultivars and five selections. There was no difference in browning susceptibility between fruit harvested at mature green or breaker stages of maturity. Freshly sliced carambola browned only slightly when exposed to air, but packaged slices that had been stored for 2 or more wk at 4.4ЊC browned rapidly (within 6 hr) when exposed to air. Whole fruit stored at 4.4ЊC for up to 6 wk, then sliced, showed much less susceptibility to browning. Ascorbic acid decreased and polyphenoloxidase activity increased in carambola slices during storage, but less in whole fruit. Treating slices with 1.0 or 2.5% citric acid ϩ 0.25% ascorbic acid (in water) prior to packaging was very effective in limiting browning.