Oligosaccharides in raw and processed legumes

 Oligosaccharides from several types of raw and processed legume seeds consumed in Spain, e.g. lentils (Lens culinaris L.), chickpeas (Cicer arietinum L.), red kidney beans (Phaseolus vulgaris L.), white common beans (Phaseolus vulgaris L.), “Judiones de la Granja” great white beans (Phaseolus vulgaris L.) and faba beans (Vicia faba L.), were analysed by high performance liquid chromatography. The total sugar content ranged from 6.69% to 9.99%, and oligosaccharides represented 25–46% of the total sugar, in the various dry legumes. The main oligosaccharide in raw faba beans was verbascose (3.32%), and stachyose in the remaining legumes (2.21–3.23%). Different amounts of sucrose and traces of glucose, fructose and small amounts of inulin were present in raw samples of all the legumes. After soaking in tap water the loss of oligosaccharides was lowest in red beans (1.25%) and highest in common white beans (27.6%). Pressure cooking, without previous soaking, resulted in no oligosaccharide loss in common white beans but a loss of up to 32% in chickpeas. After pressure cooking of soaked legumes, the loss of stachyose ranged from 14.2% in red beans up to 35.9% for lentils. Substantial amounts of flatus-producing factors can be eliminated by common processing methods. Received: 12 May 1997 / Revised version: 17 July 1997     

Resistant starch and potential glycaemic index of raw and cooked legumes (lentils, chickpeas and beans)

 The amount of resistant starch (RS) in raw and processed legumes, lentils, chickpeas and beans was analysed. In addition, the effect of cooking on the availability of legume starches to enzymes, which may influence the glycaemic response, was studied. Raw legumes were found to have higher RS values (16–21%) than retrograded or cooked ones (4–8%). Cooling increased RS yields, whereas reheating maintained or decreased the value depending on the sample. On the other hand, the kinetics of starch hydrolysis revealed that the rate of digestion was higher for cooked seeds and retrograded flours (15–21% of total starch digested) than for raw flours (5–8% of total starch digested). The estimated glycaemic indices (GIs), i.e. GI₁ from the Hydrolysis Index (HI) and GI₂ from the percentage of hydrolysis within 90 min (H ₉₀), were well correlated with the reported GI values (r = 0.96 and r = 0.95 respectively, P≤ 0.05). Received: 22 September 1997 / Revised version: 24 November 1997     

Profiles of phenolic compounds of Apis mellifera and Melipona spp. honeys from Venezuela

 The size of the indigestible fraction of, and the availability of starch in, commercial frozen and canned peas was studied in vitro. The total dietary fibre content, as determined by chemical analysis, was similar in both samples (27%); nevertheless, appreciable amounts of resistant starch (4.4–6.9%) and resistant protein (4.7–5.4%) were found in the insoluble dietary fibre gravimetric residue. Other indigestible components of the pea were an additional fraction of resistant starch, not associated with insoluble dietary fibre, and the oligosaccharides inulin and stachyose. The total amount of starch (25.8–36.1%) was very different between frozen and canned samples, and was inversely correlated with their sucrose contents (14.2–6.7%). Our results indicate that 35–40% of the dry weight of peas is not digested in vitro and that the relative rate of glucose release by α-amylase hydrolysis seems to be decreased in the presence of resistant starch. Received: 8 October 1996     

Chemical Composition,Starch Bioavailability and Indigestible fraction of Common Beans (Phaseolus Vulgaris L.)

In Mexico, consumption of beans represents 15% of the normal diet of the population in rural zones. Four common bean varieties cultivated in Mexico were studied regarding their chemical composition, starch digestibility and indigestible fraction. The protein level in the samples Huasteco, Tacana and TLP 19 was not different (α = 0.05), but Veracruz cultivar had the highest protein and ash content, and the lowest lipid level. Differences in chemical composition were determined in the cultivars studied. Total starch (TS) ranged between 33.6 and 36.7%, and the cultivars Tacana, TLP 19 and Veracruz were not different in starch content (α = 0.05). The available starch (AS) determined represented between 74 and 87% of TS, due to the resistant starch content and perhaps some complex formed between starch and protein or starch and polyphenols, by the high level of the indigestible fraction determined in the beans. The in vitro α‐amylolysis rate was similar for the different varieties, except for Veracruz cultivar which presented a slightly lower hydrolysis rate.     

Growth characteristics and fermentation products of Streptococcus salivarius subsp. thermophilus, Lactobacillus casei and L?. fermentum in soymilk

 Growth and substrate consumption of Lactobacillus fermentum, L. casei, and Streptococcus salivarius subsp. thermophilus were studied in soy milk. All cultures tested metabolized sucrose in the range of 60–75% with various rates of sugar consumption, but only L. fermentum was able to hydrolyse stachyose (85%). Lactic acid was the major end-product while acetic acid was only produced by L. casei and L. fermentum. Received: 12 June 1997     

Growth characteristics and fermentation products of Streptococcus salivarius subsp. thermophilus, Lactobacillus casei and L . fermentum in soymilk

 Growth and substrate consumption of Lactobacillus fermentum, L. casei, and Streptococcus salivarius subsp. thermophilus were studied in soy milk. All cultures tested metabolized sucrose in the range of 60–75% with various rates of sugar consumption, but only L. fermentum was able to hydrolyse stachyose (85%). Lactic acid was the major end-product while acetic acid was only produced by L. casei and L. fermentum. Received: 12 June 1997     

Moisture sorption isotherms of nutritious supplementary foods prepared from cereals and legumes for feeding rural mothers and children

 Four types of supplementary foods (FSs) based on popped wheat (Triticum vulgare), ragi (Eleusine coracana), bajra (Pennisetum americanum) and sorghum (Sorghum bicolor) blended with soy (Glycine max Merr) and bengalgram (Cicer arietinum) and fortified with vitamins and minerals were prepared on a pilot plant scale. All the FSs contained 10–20% proteins and 350–380 kcal of energy. Moisture sorption characteristics of these FSs were evaluated at room temperature (27  °C) with a view to designing a functional package for such products. The results revealed that a moisture content of about 10% (equilibrium relative humidity 68–70%) is optimum to give a good storage stability to the products. Above the 10% moisture level the products were found to be vulnerable to microbial spoilage (mould growth), leading to quality deterioration. In order to protect these types of products from being spoiled by mould growth during storage, use of moisture-proof packaging materials based on high density polyethylene and polypropylene may be considered. Received: 13 August 1999     

Recovery of flavanones from wastes of industrially processed lemons

 The flavonoids present in the wastes and residues obtained during the industrial processing of lemons were characterized and quantified. Selected products of the juice-extraction line and essential-oil-recovery line were studied. Industrial lemon juice is characterized by containing hesperidin and eriocitrin as the main flavonoid glycosides (130 μg/ml), other minor flavanones and C-glycosylflavones. After the concentration process, the concentrated juice contained a 5-fold increase in the concentration of flavonoids, but some of the hesperidin present in the initial juice was lost. The flavanone glycosides were mainly concentrated in the peel and solid residues, where hesperidin was present as the prevailing flavonoid with concentrations of up to three times higher than those of eriocitrin. In liquid residues eriocitrin was the main flavonoid. The solid residues (peel and frit precipitates) were the most interesting sources for the industrial recovery of flavonoids (13 kg/t processed lemons). Received: 8 October 1997     

Quantitative estimation of the action of α-amylase from Bacillus subtilis on native corn starch by HPLC and HPTLC

 The optimal conditions of corn starch liquefaction and dextrinization using α-amylase from Bacillus subtilis to obtain maltodextrins with a dextrose equivalent of 12.9–23.5 were determined. The pattern of action of B. subtilis α-amylase on native corn starch was monitored using high-performance liquid chromatography (HPLC) and high-performance thin layer chromatography (HPTLC). It was possible to separate malto-oligosaccharides of up to 9 glucose units by HPLC and those of up to 12 glucose units by HPTLC, respectively. The results suggest that α-amylase from B. subtilis is an endo-specific enzyme which mainly produces two oligosaccharides, DP3 and DP6. It was shown that both methods can be successfully applied for the characterization of maltodextrins. Received: 22 August 1997     

Content of low molecular weight carbohydrates in vining peas (Pisum sativum) related to harvest time,size and brine grade

Knowledge of how the content of low molecular weight carbohydrates (LMWC), including the raffinose family oligosaccharides (RFO; raffinose, stachyose and verbascose), changes in unripe peas (Pisum sativum) around harvest time, is today limited. An early and a late maturing cultivar of peas were harvested with 24 h of each other on seven different occasions, of which three were chosen for this study. The pea samples were divided into three groups by size and brine grading, and then analysed with regard to the content of low molecular weight carbohydrates. The content of raffinose and stachyose increased in all groups during a period of 5 days. Peas that sank (sinkers) in the brine grading test had a higher content of raffinose and stachyose and a lower content of sucrose than floating peas, indicating that sinkers have reached a greater degree of maturation. The content of verbascose remained the same or decreased during the study period. In conclusion, the date of harvesting green peas for freezing affects the contents of RFO.     

Stability of sulphadimidine during raw fermented sausage preparation: reaction of sulphadimidine with nitrite

 In earlier studies of the stability of sulphadimidine (SDM) during the preparation of raw fermented sausage, some unknown reaction products were observed which have been further studied. Sausages prepared with SDM, and their corresponding brines were examined for the presence of desamino-SDM (DAS) and 4-hydroxy-desamino-SDM (SOH), as they are possible products of the reaction between SDM and the additive nitrite. After extraction, clean-up and solid-phase extraction (SPE) concentration, the compounds were identified by HPLC followed by diode array detection. The presence of SOH and DAS could be demonstrated in both sausage and brine. In sausage 2.5% of SDM was converted to DAS, while only a minor amount (0.1%) was transformed to SOH. In brine approximately 2.5% and 4% of the original amount of SDM was found as DAS and SOH, respectively. Received: 5 May 1997 / Revised version: 4 July 1997     

Stability of sulphadimidine during raw fermented sausage preparation: reaction of sulphadimidine with nitrite

 In earlier studies of the stability of sulphadimidine (SDM) during the preparation of raw fermented sausage, some unknown reaction products were observed which have been further studied. Sausages prepared with SDM, and their corresponding brines were examined for the presence of desamino-SDM (DAS) and 4-hydroxy-desamino-SDM (SOH), as they are possible products of the reaction between SDM and the additive nitrite. After extraction, clean-up and solid-phase extraction (SPE) concentration, the compounds were identified by HPLC followed by diode array detection. The presence of SOH and DAS could be demonstrated in both sausage and brine. In sausage 2.5% of SDM was converted to DAS, while only a minor amount (0.1%) was transformed to SOH. In brine approximately 2.5% and 4% of the original amount of SDM was found as DAS and SOH, respectively. Received: 5 May 1997 / Revised version: 4 July 1997     

Material properties of processed fruit and vegetables I. Effect of extraction and thermal treatment on apple parenchyma

 Using apple mash prepared from apple parenchyma, the effect of the processing steps of cold and warm water treatment, respectively, on structure and material properties of treated mashes, as well as dried and rehydrated materials with cellular structure (MCS), compared to alcohol-insoluble substance (AIS), were investigated. Cold water treatment gives rise to pectin-enriched, relatively large and mechanically stable cell clusters which show good elastic and solid-state properties in aqueous dispersions. However, warm water treatment effects a thermal hydrolytic degradation of pectin in the MCS whereby the mechanical cell separation is simplified and reduced structural stability of the dispersions can be observed. AIS contains the biggest particles and best material properties in comparison to MCS. The connection between structural parameters which are affected by processing and material properties, in addition to the importance of AIS and MCS, respectively, as model substrates, are discussed. Received: 27 June 1997 / Revised version: 17 October 1997     

Chemical composition,dietary fibre and resistant starch contents of raw and cooked pea,common bean,chickpea and lentil legumes

The chemical composition and the contents of resistant starch and soluble and insoluble dietary fibre of pea (Pisum sativum L.), common bean (Phaseolus vulgaris L.), chickpea (Cicer aretinum L.) and lentil (Lens culinaris Med.) legumes, were studied. Raw and freeze-dried cooked samples were used, both in the form of flour. Protein values of the legumes ranged from 18.5 to 21.9 g/100 g for the raw grains and from 21.3 to 23.7 g/100 g for freeze-dried cooked legumes. Chickpea stood out for the highest lipid content (p < 0.05), the lowest insoluble fibre values, and soluble dietary fibre not detected. The average content of resistant starch found in the legumes did not differ statistically (p > 0.05), being 2.23 ± 0.24 g/100 g for freeze-dried cooked legumes, and showing a slight reduction in comparison to the raw form.     

Production of enterotoxin A and thermonuclease by Staphylococcus aureus in legumes

Growth, enterotoxin A (SEA) and thermonuclease (TNase) production of S. aureus (Strains CP 7 and FRI 722) was determined in media produced from the following heat or irradiation sterilized legumes: peas, black beans, mung beans, adzuki beans and soybeans. Media containing the five legumes alone or in combination with Brain Heart Infusion Broth (BHI) were tested. With the exception of heat-sterilized black beans and adzuki beans, S. aureus growth was excellent in all media with cell counts after 48 h (25 °C) exceeding 10⁸ cfu/ml. In black beans and adzuki beans cell counts were 1–2 log-cycles lower. Enterotoxin A was produced in amounts of 33 to 72 ng/ml in BHI after 48 h. Almost no toxin was produced in the four different beans following heat or irradiation treatment; in peas the toxin concentration reached 14 to 15 ng/ml. In the medium prepared from irradiated soybeans and BHI the final toxin concentration was about the same as in BHI alone. In all the other media consisting of a combination of legumes with BHI toxin concentrations were there to four times higher than in BHI alone. Production of thermonuclease showed variation and did not always correlate with enterotoxin production.     

Rocket immunoelectrophoresis (RIE) for determination of potentially allergenic peanut proteins in processed foods as a simple means for quality assurance and food safety

 Peanuts are one of the most allergenic foods known. The presence of hidden allergens in processed food for reasons of mislabelling or cross-contamination expose allergic individuals to unpredictable risks, especially since highly sensitized subjects may experience severe anaphylactic reactions. The protection of consumers requires specific and sensitive methods for the detection of trace amounts of potentially allergenic peanut components. A rocket immunoelectrophoresis (RIE) procedure was developed allowing the detection of even spurious contaminations with peanut protein. For precipitation of peanut protein a commercially available antiserum was used. By amplifying precipitates with a secondary immunodetection step, 20 ng/ml peanut protein in chocolate extract, equivalent to 0.0002% peanut in chocolate, could still be detected. Model chocolate spiked with various amounts of peanut was investigated down to 0.001% peanut (10 ppm), the limit of quantitative determination. The method was optimized for detection of peanut in chocolate samples. Non-chocolate samples had to be standardized with a chocolate matrix prior to analysis in order to obtain a uniform response. Cross-reactivities with other food proteins did not occur. The method showed high recoveries of 85–101% for chocolate samples down to 10 ppm peanut and good reproducibility with coefficients of variation of ≤ 5 % for samples of ≥ 15 ppm peanut protein. The applicability of this method in the detection of peanut protein in various food commodities was demonstrated: two unlabelled products and two products which did not have peanut listed as an ingredient were identified as containing peanut protein. In all cases where peanut was listed, peanut protein could be determined. The results of RIE were always confirmed by those of a new cell-mediator-release assay that is based on a rat basophil leukaemia (RBL) cell-line (RBL-2H3), cells that are a functional equivalent to mucosal mast cells. Measuring the release of β-hexosaminidase resulting from cross-linking of basophil-bound peanut-specific immunoglobulin E, the assay mimics a main event of the allergic type-I reaction. The cell assay was adapted for food matrices and peanut could be detected down to 0.01% which additionally demonstrated in vitro that even trace amounts of peanut protein could elicit allergic reactions. Received: 28 May 1997 / Revised version: 11 July 1997     

Rocket immunoelectrophoresis (RIE) for determination of potentially allergenic peanut proteins in processed foods as a simple means for quality assurance and food safety

 Peanuts are one of the most allergenic foods known. The presence of hidden allergens in processed food for reasons of mislabelling or cross-contamination expose allergic individuals to unpredictable risks, especially since highly sensitized subjects may experience severe anaphylactic reactions. The protection of consumers requires specific and sensitive methods for the detection of trace amounts of potentially allergenic peanut components. A rocket immunoelectrophoresis (RIE) procedure was developed allowing the detection of even spurious contaminations with peanut protein. For precipitation of peanut protein a commercially available antiserum was used. By amplifying precipitates with a secondary immunodetection step, 20 ng/ml peanut protein in chocolate extract, equivalent to 0.0002% peanut in chocolate, could still be detected. Model chocolate spiked with various amounts of peanut was investigated down to 0.001% peanut (10 ppm), the limit of quantitative determination. The method was optimized for detection of peanut in chocolate samples. Non-chocolate samples had to be standardized with a chocolate matrix prior to analysis in order to obtain a uniform response. Cross-reactivities with other food proteins did not occur. The method showed high recoveries of 85–101% for chocolate samples down to 10 ppm peanut and good reproducibility with coefficients of variation of ≤ 5 % for samples of ≥ 15 ppm peanut protein. The applicability of this method in the detection of peanut protein in various food commodities was demonstrated: two unlabelled products and two products which did not have peanut listed as an ingredient were identified as containing peanut protein. In all cases where peanut was listed, peanut protein could be determined. The results of RIE were always confirmed by those of a new cell-mediator-release assay that is based on a rat basophil leukaemia (RBL) cell-line (RBL-2H3), cells that are a functional equivalent to mucosal mast cells. Measuring the release of β-hexosaminidase resulting from cross-linking of basophil-bound peanut-specific immunoglobulin E, the assay mimics a main event of the allergic type-I reaction. The cell assay was adapted for food matrices and peanut could be detected down to 0.01% which additionally demonstrated in vitro that even trace amounts of peanut protein could elicit allergic reactions. Received: 28 May 1997 / Revised version: 11 July 1997     

The texture of low calorie grape juice jelly

 In this work the production of grape juice jellies with a low methoxyl pectin was studied. Availability of this kind of jelly will increase the range of dietetic products and is a promising alternative use for grapes surplus to the needs of the enological industry. The formulation of the jellies was optimized by response surface methodology (RSM), using as independent variables total sugar content (20 – 50°Brix), low methoxyl pectin content (0.5 – 1.5%) and processing temperature (55 – 90°C) at five levels. The dependent variable was the overall balance (B), a response obtained from sensory analysis. B was chosen from a series of sensory attributes evaluated by a test panel and the data treated by principal component analysis (PCA). The resulting polynomial equation (R ² = 0.92) showed the maximum value for B to occur for a jelly produced with 38°Brix of total sugar, 1.2% of low methoxyl pectin and a processing temperature of 69°C. The sensory-optimized jelly was objectively characterized for texture and dynamic rheological behaviour. Received: 2 October 1996 / Revised version: 7 January 1997     

岩藻低聚糖的酶法制备及活性分析

利用岩藻聚糖硫酸酯酶对岩藻聚糖硫酸酯进行降解,获得岩藻低聚糖。利用均匀设计和正交设计方法,设计122组试验,通过Matlab软件建立3层BP网络模型模拟酶解过程,运用遗传算法对上述网络进行寻优。并利用D-半乳糖致衰老小鼠模型,对岩藻低聚糖和岩藻聚糖硫酸酯的抗氧化活性进行对比研究。结果表明,在加酶量0～24U/mg、酶解温度20～40℃、酶解时间0～4h的酶解条件下,产物分子质量会发生显著性变化,选取上述范围作为寻优范围。遗传算法寻优结果表明,当加酶量20.7U/mg、酶解温度26℃、酶解时间2.3h时,能够获得最大抗氧化活性的岩藻低聚糖,该产物的1,1-二苯基-2-三硝基苯肼自由基清除率达到85.1%,分子质量为18.2kDa。体内动物实验结果表明,岩藻低聚糖较岩藻聚糖硫酸酯在羟自由基清除率、丙二醛活力及减少过氧化氢酶含量等抗氧化指标方面都有显著提高（P＜0.05）。本实验为工业化制备高抗氧化活性岩藻聚糖硫酸酯水解产物提供了一定实验支撑。