APPLICATION OF LOW TEMPERATURE HEAT TREATMENTS BEFORE RETORTING IMPROVES THE QUALITY OF CANNED POTATOES

Low temperature heat treatments applied to potatoes (cv Atlantic, Snowden, and Pike) prior to retorting were evaluated for their effect on sloughing in canned potatoes. Blanching in water for 30 min at 60 - 77C before retorting decreased potato breakage, brine turbidity, and brine soluble solids without adversely affecting firmness or color. Low temperature blanching was only effective when potatoes were retorted in CaCl₂ (0.1 %) brine solutions. Sloughing was also decreased by a hot-fill and hold process that utilized brine fill temperatures of 77 − 93C followed by a 30 min hold in CaCl₂ (0.1 %) brine before commercial sterilization. The hot-fill and hold method for control of sloughing in canned potatoes is an improvement over current methods because it eliminates the need for a blanching step and requires only minimal changes in equipment or product flow.     

PHYSICAL PROPERTIES OF TWO POPULAR INDIAN POTATO VARIETIES

Physical properties of potatoes, often required for analyzing heat and mass transfer during cooling and storage applications, were determined for the Kufri Jyoti and Kufri Sinduri varieties. The average values of linear dimensions, D_p, S_p, R_a, mass, ρ, A_cand A of these two varieties were measured. The Kufri Jyoti was found to have comparatively more variations in a, b and c than the Kufri Sinduri. The average values of D_p, S_p, R_a, ρ, A_cand A for the Kufri Jyoti and Kufri Sinduri were found to be 4.647 and 3.692 cm; 82.45 and 86.65%; 82.99 and 91.78%; 1113.3 and 1092.1 kg/m³; 30.86 and 12.10 cm²; and 79.05 and 47.10 cm², respectively. The average values of ε, D_v, average D_pi, λand bulk density for the Kufri Jyoti and Kufri Sinduri in a commercially used 50‐kg gunny bag were found to be 0.42 ± 0.01 and 0.43 ± 0.008; 4.998 and 4.056 cm, 4.817 ± 0.534 and 3.922 ± 0.211 cm, 0.58 and 0.57; and 647.6 and 622.5 kg/m³, respectively. Relationships were also established for calculating the A of potato as a function of volume and weight.     

Formation of aldehydes from S-alk(en)ylcysteines and their sulfoxides

Fourteen S-alk(en)ylcysteines, S-methyl, S-ethyl, S-propyl, S-isopropyl, S-allyl, S-butyl, S-isobutyl, S-(2-butenyl), S-(3-butenyl), S-pentyl, S-isopentyl, S-prenyl, S-hexyl and S-(methylthiomethyl) derivatives and the corresponding sulfoxides, including those naturally occurring in alliaceous and brassica vegetables, were oxidised in model solutions with either glyoxal or potassium peroxodisulfate. The Strecker aldehydes, 2-[alk(en)ylthio]ethanals, preferentially formed by oxidation of the individual S-alk(en)ylcysteines were identified and their sensory properties and odour threshold values evaluated and described. These Strecker aldehydes were accompanied by the corresponding 2,4-bis[alk(en)ylthio]but-2-enals formed by subsequent aldolisation/dehydration reactions of the 2-[alk(en)ylthio]ethanals. 2-(Methylthio)ethanal and 2-(allythio)ethanal have been identified as the minor constituents among cooked broccoli and cooked garlic volatiles for the first time. Despite being formed in relatively small amounts, they might contribute to the overall aroma of processed vegetables.     

A comparison of the retention of vitamins B1, B2 and B6, and cooking yield in pork loin with conventional and enhanced meal-service systems

In this study different simulated meal-service systems were compared with respect to vitamin B₁, B₂ and B₆ retention, and cooking yield in pork roasts. Initially the roasts were cooked traditionally or sous vide. No significant differences were observed between cooking methods. Further processing included warm-holding, conventional cook-chill, modified atmosphere packaging (MAP) and sous vide. Compared to retention in the freshly cooked samples, vitamin B₂ retention remained unaffected, irrespective of the meal-service system used and storage period. As regards vitamin B₁ and vitamin B₆, retentions declined significantly, by 14% and 21% respectively during 3 h of warm-holding, and by 11% and 19% respectively after 1 day of storage and subsequent reheating (cook-chill, MAP and sous vide). Vitamin B₁ retention declined by an extra 4% during storage for 14 days (sous vide) (not significant) It is concluded that conventional and enhanced meal-service systems produce roasts with similar quality attributes. Adjustment factors of 15% and 20% for vitamin B₁ and B₆ respectively are suggested, in addition to the losses caused by the initial heat treatment.     

Acrylamide content in fried chips prepared from irradiated and non-irradiated stored potatoes

The content of reducing sugars and asparagine, responsible for the formation of acrylamide, was determined in eight Indian potato varieties. Among these, Kufri chipsona-2 and Kufri lavkar showed the lowest level of reducing sugar (680.68 ± 56.50 mg/kg) and asparagine (2074.36 ± 122.27 mg/kg), respectively. The acrylamide content in potato chips prepared from Kufri chipsona-2, the variety that is used commercially in India for making potato chips was also the lowest. Irradiation of this variety of potatoes at the sprout inhibition dose of 60 Gy and subsequent storage for six months showed a 10.7% lower content of reducing sugars at both 14 and 4 °C. The acrylamide content was 8.41% and 6.95% lower in chips from irradiated potatoes stored at 14 and 4 °C than the corresponding non-irradiated controls. The colour of the chips was also better in irradiated potatoes as judged from the L∗ and a∗ values.     

Direct isocratic normal-phase HPLC assay of fat-soluble vitamins and β-carotene in oilseeds

Non-conventional seeds are of current interest because their constituents have unique chemical properties and they may augment the supply of edible oils. The study of seed oils for their minor constituents is useful in order to use both oil and the minor components effectively. Fat-soluble vitamins (FSV) and pro-vitamin A (#-carotene) are of particular importance in nutrition. Although fatty acid profiles of the selected seeds have been reported, no data about their FSV composition are yet available. Black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.), and niger (Guizotia abyssinica Cass.) seed oils were extracted with two different solvents [n-hexane (H) or chloroform/methanol (CM) (2:1 v/v)] in a Soxhlet-extractor. An isocratic normal-phase high-performance liquid chromatography (NP-HPLC) method for FSV and #-carotene analysis using a Zorbax-Sil silica column and an ultraviolet (UV) detector was developed. Isooctane/ethylacetate (96:4 v/v) was used as the eluant for the simultaneous elution of vitamin E, while isooctane/2-propanol (99:1 v/v) was used to elute other FSV and #-carotene. Saponification of seed oil samples was not required. The seed oil or its diluted solution in the selected mobile phase was therefore directly injected onto the HPLC column. All tocopherol derivatives were identified in seed oil samples. The main constituents in black cumin and niger seed oils were !- and %-tocopherols, whereas #-tocopherol (575-672 µg g^-1 oil) was the major tocopherol in coriander seed oil. #-Carotene was measured in high levels in coriander seed oil (739-892 µg g^-1 oil), followed by niger seed oil (574-702 µg g^-1 oil) then black cumin (569-593 µg g^-1 oil). Examined seed oils, especially niger seed oil, were characterized by high amounts of phylloquinone (>0.2% of oil content). Retinoic acid, vitamin A-alcohol, vitamin D (D₂+D₃), and menadione (vitamin K₃) have not been detected in all oilseed samples. The aim of the present investigation was to estimate FSV and #-carotene content of studied oilseeds. The results obtained show that because of their specific FSV constitution, these seed oils are promising new oils.     

Sensory and chemical evaluation of Thymus zygis L. essential oil and compressed CO2 extracts

The effects of the extraction procedure on the sensory and chemical evaluation of Thymus zygis L. aromatic extracts obtained by hydro distillation and compressed CO₂ extraction were studied. Compressed CO₂ extractions were performed at a temperature of 313 K and 10 and 15 MPa of pressure for 60 min. Aromatic extracts were analysed by GC and GC-MS. Sensorial analysis of the aromatic extracts incorporated into a sunflower oil was carried out by a panel of 20 trained members. The main compounds of Thymus zygis essential oil obtained by Clevenger distillation are: p-cymene (13.6%), thymol (23.8%), geraniol (18.2%), and geranyl acetate (16.3%). The compositions of supercritical extracts are quite different. The detection threshold of Thymus zygis essential oil was 0.001 mg/kg sunflower oil. The preferred level of essential oil incorporation was 0.02 mg/kg sunflower oil (P<0.05). Sensorial attributes were correlated with chemical compositions and it can be concluded that extracts with higher levels of phenols and geranyl acetate were preferred.     

Photobacterium phosphoreum isolated as a luminescent colony from spoiled fish, cultured in model system under controlled atmospheres

A luminescent colony isolated from spoiled hake, tentatively identified as Photobacterium phosphoreum, was cultured in a sterile fish juice at 1ǃ °C. Growth, trimethylamine, off-odour and biogenic amines production under four gas mixtures (60% CO₂/15% O₂/25% N₂, 60% CO₂/40% O₂, 40% CO₂/60% O₂, 40% CO₂/40% O₂/20% N₂) and under air were tested. Aerobically incubated bacteria showed the highest counts and trimethylamine production after 43 days of storage (>10⁸ cfu/ml and 28 mg TMA-N/100 ml, respectively). Mixtures containing CO₂ and O₂ seemed to exert an inhibitory effect both on growth and trimethylamine production by this bacteria, specially for mixtures containing 60% CO₂. Off-odour production was detected when the bacteria was incubated in air from day 15. Cadaverine was the major amine produced by P. phosphoreum followed by histamine. Putrescine and spermidine production generally increased during the aerobic incubation. However, the level of histamine and tyramine was higher under the gas mixture containing 60% CO₂/15% O₂/25% N₂ than in air, whereas the agmatine production seemed to be enhanced under any gas mixture assayed.     

Some properties of potatoes and their starches II. Morphological,thermal and rheological properties of starches

The physico-chemical, morphological, thermal and rheological properties of the starches separated from different potato cultivars (Kufri Jyoti, Kufri Badshah and Pukhraj) were studied. The starches separated from the mealier cultivars (Kufri Jyoti and Kufri Badshah) showed lower transition temperatures (T_o; T_p and T_c), peak height indices (PHI), and higher gelatinization temperature range (R) and enthalpies of gelatinization (ΔH_gel) than the starch from the least mealy cultivar (Pukhraj). Swelling power, solubility, amylose content and transmittance values were observed to be higher for Kufri Jyoti and Kufri Badshah potato starches, while turbidity values were lower for these starches. The rheological properties of starches, measured using a dynamic rheometer, showed significant variation in the peak G′, G″ and peak tan δ values. Kufri Badshah and Kufri Jyoti starches showed higher peak G′, G″ and lower peak tan δ values than Pukhraj starch during heating and cooling cycles. Kufri Jyoti and Kufri Badshah starches showed higher breakdown in G′ than starch from the Pukhraj potato cultivar. The large-sized granules of the starches from Kufri Badshah and Kufri Jyoti appeared to be associated with higher values of peak G′ and G″ and consistency coefficient. Starch from the least mealy cultivar (Pukhraj) showed higher retrogradation, which increased progressively during storage at 4 °C for 120 h.     

Linalool disaccharides as flavour precursors from green coffee beans (<Emphasis Type="Italic">Coffea arabica</Emphasis>)

Two linalool disaccharides, isolated from green coffee beans (Coffea arabica), were identified as 3(S)-linalool-3-O-#-D-glucopyranosyl-#-D-apiofuranoside and 3(S)-linalool-3-O-#-D-glucopyranosyl-!-L-arabinopyranoside. The structures were established by one- and two-dimensional ¹H and ¹³C NMR spectra as well as by ESI MS/MS spectra.     

Thermal and long-term freezing stability of ivermectin residues in sheep milk

The stability of ivermectin residues in sheep milk under conditions of pasteurization (74 °C, 40 s), high pasteurization (80 °C, 1 min), and boiling (100 °C, 10 s) based on residue content (at a level of concentration of about 2 µg/kg and 30 µg/kg of H₂B_1a) and sort of ingestion (in vitro, in vivo) was studied. None of these factors influenced concentrations of ivermectin in the matrix investigated. Residues of ivermectin were also stable in milk after one year of freezing at -20 °C. After two years of freezing they had diminished by approximately one quarter. The concentration of the H₂B_1a component was analyzed using a combined HPLC method with fluorescence detection. Samples were extracted with acetonitrile and cleaned-up using a solid phase extraction on C₈ minicolumns. Eluate was concentrated under stream of nitrogen and dry extracts were pre-column derivatized with trifluoroacetic anhydride and N-methylimidazole. The method used was extensively validated.     

Distinguishing organic wines from normal wines on the basis of concentrations of phenolic compounds and spectral data

This study was undertaken to determine whether it is possible to distinguish organic wines from normal wines on the basis of chemical composition and spectral data. A total of 58 wine samples including organic and normal red and white wines from France and Germany were analysed. The concentrations of several phenolic compounds, including trans-resveratrol, were determined using reversed-phase high-performance liquid chromatography with both diode array and coulometric electrode array detection. In addition, total phenols, total acids, pH and SO₂ were determined. The ultraviolet-visible (UV-vis) spectra of wines were measured, and the absorbances at four different wavelengths were determined. The data were processed statistically using principal component analysis (PCA). Despite several different combinations of variables, separation of white wines was only achieved according to geographical origin. PCA differentiated well between organic Burgundy red wines and normal Burgundy wines. The separation was based on the concentrations of caffeic and gallic acids, total phenol content and the absorbance ratios A₂₅₄/A₂₇₆, A₂₇₆/A₃₂₀ and A₃₂₀/A₅₂₀. PCA was unable to differentiate organic white wines from corresponding normal wines. The mean trans-resveratrol concentrations of 16 organic red wines and 16 normal red wines were 5.6 mg/l and 2.9 mg/l, respectively. The highest concentration, 14,5 mg/l, was found in an organic red wine from the Loire district in France.     

Physicochemical,thermal and pasting properties of starch separated from γ-irradiated and stored potatoes

The morphological, thermal and pasting properties of starch separated from potatoes of three varieties (Kufri Chandramukhi, Kufri Jyoti and Kufri Chipsona-2), treated either with CIPC (isopropyl N-(3 chlorophenyl) carbamate) or γ-irradiation (Co⁶⁰, 0.1 and 0.5 kGy) and subsequently stored at 8, 12 and 16 °C for 90 days, were studied. Scanning electron microscopy (SEM) showed the presence of oval and irregular shaped starch granules with a diameter range of 15–16 μm. Mean granule size of starch separated from potatoes stored at 12 °C ranged from 18–25 μm and irradiation treatment resulted in an increase in the proportion of small size granules. The irradiation of potatoes with 0.5 kGy resulted in starch with significantly lower peak-, trough- and breakdown-viscosity as compared to starch from potatoes treated with either CIPC or 0.1 kGy irradiation. The irradiation of potatoes with 0.5 kGy caused a significant increase in setback and pasting temperature. Pasting temperature of starch was observed to vary with the storage temperature. Starch separated from potatoes stored at higher temperature showed lower pasting temperature and vice versa. The starch from potatoes stored at 8 °C showed higher peak-, trough- and breakdown-viscosity and lower setback. Peak viscosity increased and swelling volume decreased with increase in storage temperature. FTIR spectra showed that the starch from irradiated potatoes displayed a significant decrease in the intensity of the C–H stretch region between 2800 and 3000 cm⁻¹, which was observed to be irradiation dose-dependent, and higher with 0.5 than 0.1 kGy. However, a slight broadening of O–H stretch (3000–3600 cm⁻¹) in starches from irradiated potatoes was observed. The spectral changes caused by γ-irradiation were apparent in the O–H stretch (3000–3600 cm⁻¹), C–H stretch (2800–3000 cm⁻¹) and bending mode of water (1600–1800 cm⁻¹).     

Stereoselectivity of the β-lyase-catalyzed cleavage of <Emphasis Type="Italic">S</Emphasis>-cysteine conjugates of pulegone

Stereoisomers of 8-S-cysteinyl-p-menthan-3-one synthesized from (R)- and (S)- pulegone by Michael addition of cysteine were characterized by means of GC, GC-MS, LC-MS, and ¹H-NMR. Conjugates were treated with three sources of cysteine-S-conjugate #-lyase: (i) a crude enzyme extract prepared from Eubacterium limosum, (ii) tryptophanase from E. coli and (iii) yeast cells. The result was liberation of 8-mercapto-p-menthan-3-one, a powerful flavoring substance exhibiting a cassis-type odor note. The enzyme-catalyzed cleavage of the thio-ether bond proceeded with low enantioselectivity. Discrimination of diastereoisomers was more pronounced with a clear preference of the cis-configured substrates.     

Kinetics of 3-chloropropane-1,2-diol (3-MCPD) degradation in high temperature model systems

A study of the decay kinetics of 3-chloropropane-1,2-diol (3-MCPD) at high temperatures in aqueous model systems is reported. Data obtained over the pH range 5-6.5 and temperatures of 80-142 °C agreed well with a predicative model derived from earlier kinetic data. The results showed that 3-MCPD was unstable in aqueous solutions approaching infinite dilution at temperatures above 80 °C. Comparison of the experimental decay of 3-MCPD with that based on the kinetic parameters A (=10^{7.73347+0.83775pH}s-1) and E_a (=119.2 kJ mol^-1) was good to within 20% over the temperature and pH ranged studied. A putative mechanism for the degradation reaction is discussed together with the implications for the decay and formation of 3-MCPD in food systems.     

Effect of controlled and modified atmospheres on the production of biogenic amines and free amino acids during storage of hake

Free amino acids (FAAs) and biogenic amines were determined in whole hake (Merluccius merluccius L) stored in bulk under controlled or modified atmosphere (60% CO₂:15% O₂:25% N₂) for 12 days at 2 °C and followed by storage in trays either under the same special atmosphere or under air for 31 days at 2 °C, which was the control. At the end of the storage, significant differences were observed (PА.05) in the amino acids isoleucine, leucine, methionine, phenylalanine, valine, glutamic acid and glycine between the control lot and the treated lots, and it was the control lot which exhibited the highest concentrations. However, the lots kept in special atmospheres exhibited higher levels of alanine, #-alanine, threonine, and tryptophan than the control lot. There was no relationship between the decreases in histidine, tyrosine, lysine, arginine and ornithine initial concentrations and the increases in their corresponding biogenic amine concentrations (histamine, tyramine, cadaverine, agmatine and putrescine, respectively) which appeared as a result of decomposition of fish by decarboxylation of the FAA. Significant differences (PА.05) were observed in the biogenic amine concentrations among the lots kept under special atmospheres. The bulk-stored lot in controlled atmosphere for the first 12 days and then packed in trays with modified atmospheres exhibited the lowest levels of biogenic amines, except for agmatine, throughout storage.     

Effect of controlled atmospheres enriched with O2 in formation of biogenic amines in chilled hake (Merluccius merluccius L.)

Changes in biogenic amines (tyramine, histamine, putrescine, cadaverine, agmatine and spermidine) contents during the storage of chilled hake in a controlled atmosphere with four gas mixtures of different CO₂ and O₂ concentrations, (CO₂/O₂/N₂ at 60/15/25, 40/40/20, 60/40/0 and 40/60/0 respectively) were studied. Biogenic amines were determined by high-pressure liquid chromatography with post-column derivatization and ortho-phtaldehyde. Histamine levels, potentially the most toxic amine in hake, were very low during storage. The amine in hake with the highest level was cadaverine. Spermidine and putrescine had very high levels at the beginning of the storage. However, agmatine and tyramine were not detected in the source raw material. An increase in biogenic amines was observed in the control lot from day 12 of storage except for agmatine, where levels began to increase earlier. Cadaverine and agmatine could be used as control indices due to their behaviour during the storage period studied. The varying O₂ and CO₂ concentrations in the different atmospheres did not seem to affect the production of spermidine. The high levels of CO₂ in thelot in M1 atmosphere were not sufficient to inhibit the production of biogenic amines. However, the high O₂ concentration had an inhibiting effect on the production of biogenic amines. Therefore, the formation of biogenic amines was inhibited by controlled atmospheres with oxygen-enriched binary gas mixtures.     

The \delta{}^{18}{\rm O} -value of the p-OH group of L-tyrosine permits the assignment of its origin to plant or animal sources

The biosynthesis of L-tyrosine in plants by the shikimate pathway via arogenate implies that the oxygen atom in the p-position originates from D-erythrose with a d¹⁸O \delta{}^{18}{\rm O} -value near +30‰ above leaf water, while its synthesis in animals by hydroxylation of external L-phenylalanine with O₂ as oxygen source and a kinetic isotope effect k₁₆/k₁₈ɏ.018 demands a d¹⁸O \delta{}^{18}{\rm O} -value near +6‰. These expectations are fully confirmed by experimental data from the ¹⁸O-pattern analysis of natural aromatic compounds. The result is considered as a basis for the assignment of L-tyrosine and L-tyrosine-derived material of plant or animal origin, respectively, and for the determination of the relative amounts of plant and animal material in food and animal feed.     

Treatment of Potato Processing Wastewater with Coagulating and Polymeric Flocculating Agents

Reduction of wastewater strength in abrasive-peeled, lye-peeled, and steam-peeled potato processing wastewater using 4 inorganic salts and 11 polymers was investigated. Treatment of wastewater with 150 mg/ L FeCl₃ 6H₂O + 20 mg/L Purifloc Anionic Polymer #23 aided in coagulation and flocculation of suspended solids of effluent from abrasive-peeled potatoes including greater than 90% reduction in chemical oxygen demand (COD), total suspended solids (TSS) and turbidity. Treatment with 300 mg/L CaCl₂+ 25 mg/L Purifloc #23 reduced COD and TSS levels in wastewater from lye-peeled potato by 69% and 76%, respectively. In steam-peeled effluent, 350 mg/L CaCl₂+ 25 mg/L Nalco 7122 reduced TSS by 90% and COD by 60%. Waste strength of effluent from processing potatoes can be substantially reduced by treating with coagulating and flocculating agents before discharging into municipal or other treatment systems.     

Relationship among fecal coliforms and <Emphasis Type="Italic"> Escherichia coli </Emphasis>in various foods

For much of the twentieth century, coliform bacteria and especially Escherichia coli have been used as indicators of possible post-processing contamination and the presence of E. coli as an indicator of fecal contamination in foods. In this study, 500 foods in 10 different groups, mainly dairy products, delicatessen products, salads, spices, cream cakes and fresh fruit and vegetable samples, were analyzed for the natural contamination of fecal coliforms and E. coli by the standard most probable number (MPN) method. The difference between weighted means of fecal coliforms and E. coli counts were only 0.246 log₁₀ MPN/g-ml (MPN/gram for solid samples, and MPN/milliliter for liquids). Enumeration results were also evaluated by Pearson's correlation coefficient ( r), Cronbach's alpha (f) and determination coefficient ( r ²) analysis. According to results, although 33 samples contained only non- E. coli fecal coliforms, the results of reliability analyses indicated that fecal coliform counts and E. coli counts may be used interchangeably ( P <0.0001). It can be said that fecal coliform or, preferably E. coli analysis is sufficient for rapid routine determination of fecal contamination, at least for those food groups analyzed in this research.