Fresh blueberries were processed into sugar and sugar-free jams and stored for 6 months at 4 and 25 degrees C. The jams were analyzed immediately after processing and over 6 months of storage for polyphenolic content, percent polymeric color, and antioxidant capacity. Processing resulted in losses of anthocyanins, procyanidins, chlorogenic acid, and ORAC in both jam types, but flavonols were well retained. Marked losses of anthocyanins and procyanidins occurred over 6 months of storage and were accompanied by increased polymeric color values. Chlorogenic acid levels also declined during storage, but flavonols and ORAC changed little. Jams stored at 4 degrees C retained higher levels of anthocyanins, procyanidins, and ORAC and had lower polymeric color values than jams stored at 25 degrees C. Sugar-free jams retained higher levels of anthocyanins and had lower polymeric color values than sugar jams late during storage. Blueberry jams should be refrigerated to better retain polyphenolics and antioxidant capacity.

This study was conducted to determine the oxidative stability of conjugated linoleic acid rich soy oil (CLARSO) and the effects of conjugated linoleic acid (CLA) levels on volatile oxidation products formed during CLARSO oxidation. CLARSO oxidative stability was determined by gravimetric analysis, peroxide value, headspace oxygen analysis and p-anisidine value. Volatile oxidation compounds were analyzed by solid phase microextraction-gas chromatography with a flame ionization detector and a mass spectrometer. CLA oxidation results were highly dependent on analytical methods used and oxidation parameters measured. The gravimetric study showed a CLA concentration effect on oxidation, which was not seen in the headspace oxygen depletion and peroxide value. Volatile oxidation data indicate that CLARSO had significantly higher (p \ 0.05) levels of pentanal and trans-2-heptenal than the other oils, but there was no significant difference between the amounts of any volatiles present in 8 and 15% CLARSO. This suggests that oxidation was greater in CLARSO and that CLA concentration did not affect oxidation.

A conjugated linoleic acid (CLA)-rich soy oil has been produced by photoisomerization of soy oil linoleic acid. Nutritional studies have shown that CLA possesses health benefits in terms of reducing certain heart disease and diabetes risk factors. Potato chips are snacks that are readily produced in the CLA-rich soy oil containing CLA levels similar to those of the oil used for frying. The objective of this study was to develop an FTIR method to rapidly determine the CLA content of oil in potato chips. Photoirradiated soy oil samples with ∼25% total CLA were mixed with control soy oil, and 100 soy oil samples with total CLA levels ranging from 0.89 to 24.4% were made. Potato chips were fried using each of these 300 g CLA rich soy oil mixtures at 175 °C for approximately 3 min. Duplicate GC-FID fatty acid analyses were conducted on oil extracted from each batch of potato chips. The chip samples were ground and then scanned using ATR-FTIR spectroscopy with the aid of a high-pressure clamp, and duplicate spectra of each sample were averaged to obtain an average spectrum. Calibration models were developed using PLS regression analysis. These correlated the CLA isomer concentrations of potato chips obtained by GC-FID fatty acid analysis with their corresponding FTIR spectral features. The calibration models were fully cross validated and tested using samples that were not used in the calibration sample set. Calibrations for total CLA, trans,trans CLA, trans-10,cis-12 CLA, trans-9,cis-11 CLA, cis-10,trans-12 CLA, and cis-9,trans-11 CLA had coefficients of determinations (R2v) between 0.91 and 0.96 and corresponding root-mean-square error of prediction (RMSEP) ranging from 0.005 to 1.44. The ATR-FTIR technique showed potential as a method for the determination of the CLA levels in unknown potato chip samples.

Jain and Proctor [1] reported pilot scale production of 20 % conjugated linoleic acid (CLA) in soy oil by photoisomerization of soy oil linoleic acid (LA) in oil triacylglycerides to CLA using an iodine catalyst. Recently, we reported in a food oil oxidation study of freshly produced CLARSO that the pro-oxidant effect of CLA and iodine was independent of concentration [2]. However, the study did not distinguish between the effect of CLA and iodine on CLA oxidation. Removal of iodine may be important if iodine is identified as prooxidant. However, if CLA is the major pro-oxidant, storage conditions and added antioxidants may be very important after iodine removal to protect against oxidation. The objective of the following study was to distinguish between the effect of added CLA and added iodine concentration on soy oil oxidative stability.Commercial RBD (Refined, bleached, and deodorized) soy oil was obtained from Riceland Foods (Stuttgart, AR) containing 52 % linoleic and 6 % linolenic acid. Resublimed iodine crystals were used as a catalyst (Alfa Aeser, Ward Hill, MA). Commercial CLA triacylglyceride (Tonalin Ò TG80) consisting of a 50:50 mixture of cis-9, trans-11 and trans-10, cis-12 was obtained from Cognis Nutrition and Health (Cincinnati, OH).Nine RBD soy oil treatments containing combinations of 0, 0.175, and 0.35 % iodine; 0, 10 and 20 % commercial CLA triacylglyceride (Tonalin Ò TG80) were prepared. CLARSO oxidative stability was studied by gravimetric analysis [3] and headspace oxygen determination. The 500-mg samples of soybean oil treated with combinations of CLA and iodine were weighed into aluminum pans.Samples were stored in an oven in the dark at 65°C for 10 days and weighed daily. Results were expressed as change in weight (mg per 500 mg of oil). To measure headspace oxygen, 3 g of oil was weighed into 10-mL amber colored glass vials and the vials were stored in an oven in the dark at 65°C for 10 days. The headspace oxygen content in each vial was determined daily by using Oxygen Analyzer-Quantek Model 905 (Quantek Instruments, Grafton, MA). Data were analyzed as a full-factorial design by analysis of variance (ANOVA) and mean comparison of triplicate runs was done by a student's t test (p \ 0.05) using JMP 9.0 (SAS Institute Inc., Cary, NC). RBD soybean oil was used in this study in place of CLARSO because the CLA in CLARSO may not allow for the effects of iodine to be determined independently. Figure 1 shows the effects of iodine and CLA concentration on weight change of RBD soy oil. The presence of iodine in the oils resulted in shorter induction time, more rapid weight increase, and therefore greater oxidation. However, there was no increase in induction time with increasing iodine levels. At 0 % CLA, both 0.175 and 0.35 % iodine had an induction period of 1 day. However, at 10 % CLA, 0.175 % iodine had an induction period of 0 days, and 0.35 % iodine had a 1-day induction period. At 20 % CLA, the two iodine concentrations again showed similar behavior with a 1 day induction period. The main...