Actual Food Systems Research Articles

Preparation and characterization of a solid dispersion of Hexahydrocolupulone and its application in the preservation of fresh apple juice.

Hops extracts and their derivatives have many important biological activities, among them, excellent antibacterial and antioxidant properties make them a promising food preservative. However, poor water solubility limits their application in the food industry. This work aimed to improve the solubility of Hexahydrocolupulone (HHCL) by preparing solid dispersion (SD) and investigating the application of the obtained products (HHCL-SD) in actual food systems. HHCL-SD was prepared by solvent evaporation with PVPK30 as a carrier. The solubility of HHCL was dramatically increased to 24.72mg/mL（25 ℃)by preparing HHCL-SD, much higher than that of raw HHCL (0.002mg/mL). The structure of HHCL-SD and the interaction between HHCL and PVPK30 were analyzed. HHCL-SD was confirmed to have excellent antibacterial and antioxidant activities. Furthermore, the addition of HHCL-SD proved to be beneficial for the sensory, nutritional quality, and microbiological safety of fresh apple juice, hence prolonging its shelf-life.

Evaluation of Potential for Butyl and Heptyl Para-Hydroxybenzoate Enhancement of Thermal Inactivation of Cronobacter sakazakii during Rehydration of Powdered Infant Formula and Nonfat Dry Milk

In previous studies, parabens in model systems enhanced the thermal inactivation of foodborne pathogens, including Cronobacter sakazakii, Salmonella enterica serotype Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes. However, few studies have been conducted to evaluate this phenomenon in actual food systems. In the present study, the potential enhancement of thermal inactivation of C. sakazakii by butyl para-hydroxybenzoate (BPB) was evaluated in powdered infant formula (PIF) and nonfat dry milk (NFDM) in dry and rehydrated forms. When PIF was rehydrated with water at designated temperatures (65 to 80°C) in baby bottles, BPB did not enhance thermal inactivation. When rehydrated NFDM and lactose solutions with BPB were inoculated and heated at 58°C, BPB enhancement of thermal inactivation of C. sakazakii was negatively associated with the concentration of NFDM solutions in a dose-dependent manner, whereas thermal inactivation was enhanced in the presence of lactose regardless of its concentration, suggesting an interaction between proteins and BPB. Fluorescence testing further indicated an interaction between BPB and the proteins in PIF and NFDM. In inoculated dry NFDM with and without BPB stored at 24 and 55°C for 14 days, BPB did not substantially enhance bacterial inactivation. This study suggests that BPB is not likely to enhance mild thermal bacterial inactivation treatments in foods that have appreciable amounts of protein.

The Effect of p-Coumaric Acid on Browning Inhibition in Potato Polyphenol Oxidase-Catalyzed Reaction Mixtures.

There has been considerable interest in using natural polyphenol oxidase (PPO) inhibitors to control browning in fruit and vegetable products. p-Coumaric acid (pCA), a common secondary metabolite of plants, has been studied as an inhibitor of PPOs/tyrosinases from several foods (e.g., mushroom, apple, and potato). However, studies on the use of pCA for the inhibition of PPO-initiated browning in actual food systems are limited. Therefore, a study was carried out to ascertain the efficacy of using pCA to limit PPO-initiated browning in fresh potato juice. The extent of browning inhibition by pCA was shown to be reaction system-dependent. Browning in potato juice was unexpectedly enhanced by the addition of pCA. This was interpreted as pCA acting as an alternative substrate with significantly higher browning efficiency; extent of browning under this condition was higher than that observed in the native potato juice. The addition of pCA to any of the model reaction mixtures (i.e., those containing semi-purified enzymes and substrates) significantly inhibited browning. The discrepancy in pCA effects on browning inhibition in different reaction systems is postulated to be mainly due to non-enzyme and non-substrate components in potato juice that participate in the post-PPO reaction sequences, which ultimately lead to brown color formation.

Water soluble biomolecules from Nepeta nuda regulate microbial growth: A case study of apple juice preservation

The following study was designed to explore antimicrobial properties of the by-product obtained in a hydro-distillation process of essential oil from Nepeta nuda L. We strived to develop a novel drink with antimicrobial self-preserving properties based on two components, N. nuda decoct and apple juice. By using 96-well plate microdilution assay it was shown that the N. nuda decoct has antimicrobial potential towards 8 bacterial and 6 fungal species, with the range of minimal inhibitory concentrations 10-300 mg/mL. By using actual food system, such as apple juice, in combination with and without short thermal treatment, we have shown that the decoct of N. nuda can inhibit the growth of food contaminant fungus Penicillium aurantiogriseum. It was determined that 3 volumes of decoct (500 mg/mL) and 22 volumes of apple juice should be mixed in order to obtain self-preserving drink resistant to P. aurantiogriseum contamination. Likewise, when thermal treatment (80 °C for 10 s) is included, self-preserving mixture of decoct and apple juice should be made in volume ratios 3:47, respectively. The designed product maintained the pleasant taste as determined by panelists during the sensorial evaluation. Chemical investigations (UHPLC-Orbitrap MS analysis) of N. nuda decoct showed that the most abundant compound was 1,5,9-epideoxyloganic acid (0.410 mg/g of dried decoct). Since N. nuda is traditionally used as a tea, we presented the novel formulation of the drink with antimicrobial properties based on the its decoct and apple juice.

Food waste measurement toward a fair, healthy and environmental-friendly food system: a critical review

PurposeGiven the importance of food waste in the economic, social, health and environmental dimensions, the purpose of this work is to detect, through a systematic and configurative literature review on food-waste-measurement methodologies, the global approaches, characteristics, limitations, opportunities and results applied within the literature. The analysis of these papers provides useful information about how far we are from international action plans and, therefore, how we need to direct programs and policies to measure and reduce food waste and ensure food security and food safety.Design/methodology/approachThe authors have conducted a systematic, configurative literature review on food waste measurement methodologies applied only within empirical studies published in academic peer-reviewed scientific journals. Based on the Commission Delegated Decision (EU) 2019/1597 of May 3, 2019 (OJEU, 2019) regarding common methodologies and minimum quality requirements for the homogeneous assessment of food waste quantities and composition, the authors investigated the issue on Web of Science Core Collection (WoS) from June 2000 to June 2020. The authors researched keywords within article titles, abstracts and author keywords by utilizing 34 different research strings.FindingsThe proposed review particularly refers to following topics: measurement methodologies applied according to the Commission Delegated Decision (EU) 2019/1597; editorial placement and publication timeline; geographical area; food supply-chain stage and publication journals; and the main features, limitations, opportunities and results for each measurement methodology as presented by authors. Among the first 48,000 results, only 58 academic articles are perfectly in line with the aim of the review, highlighting the lack of standardized methodologies, the limits of those proposed and the deficiency of comparable results to achieve sustainable international goals.Originality/valueThe proposed review is one of the few concerning food waste measurement methodologies. Food waste measurement is essential to rebalance the actual inadequate food system and to switch it toward a fair, healthy and environmentally friendly one, thereby (1) managing the human nutrition system paradox of hungry, undernourished and over-weight people; (2) reducing food insecurity; (3) ensuring each living being's access to healthy, nutritious and sustainable food; and (4) reducing environmental impacts (neutral or positive impact) and the loss of biodiversity and mitigating climate change.

Rational engineering of chromic material as near-infrared ratiometric fluorescent nanosensor for H2S monitoring in real food samples

Food pollution has aroused increasing public health concerns and poses a huge medical and financial burden today. Here, we report a facile one-pot synthesis of hydrogen sulfide (H2S)-responsive near-infrared (NIR) ratiometric fluorescent nanoprobe NIR775/Cy7Cl@HyNPs by encapsulating H2S-sensitive organic chromic cyanine dye Cy7Cl and H2S-inert fluorophore NIR775 into an amphiphilic phospholipid polymer. Because of the confinement effect of phospholipid layer, the loaded NIR775 and Cy7Cl could be brought in close proximity for fluorescence resonance energy transfer (FRET) to occur, leading to single emission of Cy7Cl at ∼ 810 nm inside nanoprobe NIR775/Cy7Cl@HyNPs. However, with the introduction of H2S, the FRET process from NIR775 to Cy7Cl is disrupted due to the stimuli-responsive chromic behavior as a result of H2S-triggered nucleophilic, leading to restoring of the fluorescence emission of NIR775 at ∼ 778 nm companied by a remarkable fluorescence decrease of Cy7Cl at ∼ 810 nm, thereby enabling nanoprobe NIR775/Cy7Cl@HyNPs to show a NIR ratiometric response toward H2S. As expected, the nanoprobe NIR775/Cy7Cl@HyNPs exhibits a prominent practicability to precisely report the levels of H2S in actual food mediums with a wide linear range of 0.0367–120.0 μM, a satisfactory limit detection of 11.0 nM, as well as an excellent specificity over other sulfur-containing substances (e.g. biothiols). This study emphasizes the promise for utilizing switchable chromic materials to develop a new category of NIR ratiometric fluorescent nanosensors facilitating accurate and reliable measurement in actual food and agriculture-related systems without any pretreatments, which is of great significance for safeguarding food safety and human health.

Antibacterial activity of a hexahydro‐β‐acids/methyl‐β‐cyclodextrin inclusion complex against bacteria related to foodborne illness

AbstractIn this study, we investigated the antibacterial activity of hexahydro‐β‐acids/methyl‐β‐cyclodextrin inclusion complex (HBA/M‐β‐CD) and researched its antibacterial mechanism against Staphylococcus aureus and Enterobacter sakazakii. The result showed that bacteria had different sensitivities to HBA/M‐β‐CD with diameters of inhibition zones ranging from 7.8 ± 0.5 to 14.8 ± 0.7 mm and minimum inhibitory concentration (MIC) values from 16.25 to 65.00 μg/mL. Among these bacteria, S. aureus (G(+)) and E. sakazakii (G(−)) were most sensitive to HBA/M‐β‐CD, and MIC value is 16.25 and 32.50 μg/mL, respectively. Also, HBA/M‐β‐CD had potential inhibition effect on the bacterial growth of S. aureus and E. sakazakii. Moreover, the treatment with HBA/M‐β‐CD led to a release of cell contents into the culture medium, indicating damage to the plasma membrane. Scanning electron microscopy revealed permeabilization of S. aureus membranes, and shrinkage and roughening of E. sakazakii cells. HBA/M‐β‐CD also reduced the activity of succinate dehydrogenase (SDH) in bacterial cultures, indicating that HBA/M‐β‐CD interfere key enzyme metabolism.Practical ApplicationsIn the actual food system of western‐style ham sausage, HBA/M‐β‐CD revealed a great antibacterial effect to control the total bacteria count, and could stabilize the pH value. The result provided the theoretical and practical basis for the application of HBA/M‐β‐CD in foods.

Cereal protein-based nanoparticles as agents stabilizing air–water and oil–water interfaces in food systems

There has been a recent surge of interest in the use of food-grade nanoparticles (NPs) for stabilizing food foams and emulsions. Cereal proteins are a promising raw material class to produce such NPs. Studies thus far have focused mostly on wheat gliadin and maize zein-based NPs. The former are effective interfacial stabilizing agents, while the latter due to their high hydrophobicity generally result in poor interfacial stability. Several strategies to modify the surface properties of wheat gliadin and maize zein NPs have been followed. In many instances, this resulted in improved foam or emulsion stability. Nonetheless, future efforts should be undertaken to gain fundamental insights in the interfacial behavior of NPs, to further explore NP surface modification strategies, and to validate the use of NPs in actual food systems.

Antifungal Activity of Protamine Salmine Hydrochloride and ε-Poly-l-Lysine in Actual Food Systems, Rice- or Wheat-Based Confectioneries

Fungal contamination often occurs in confectioneries with high saccharide content during storage. Protamine salmine hydrochloride (PSH) and ε-poly-l-lysine (ε-PL) showed stable antifungal activities in the medium supplemented with 50% (w/v) sucrose, which pH shows around neutral, as a model of confectioneries. The antifungal activities of PSH and ε-PL have also shown synergy with sodium acetate. To confirm these antifungal activities into actual food systems, dumplings and steamed breads were used as rice- or wheat-based confectionery models. They substantiated practicable antifungal activities against confectionery pollution fungus in these models. The heat stability of both PSH and ε-PL was also indicated, and the impact on the taste or flavor of these confectioneries by addition of PSH and ε-PL were confirmed as less. The results proposed that both PSH and ε-PL are effective antifungal agents in actual foods with high saccharide contents such as confectioneries, at the neutral pH conditions. Practical Applications There are practically few natural antifungal agents used effectively to the actual foods at neutral pH, because many natural antifungal agents are lipophilic, or some of them show the antifungal effects only in the acidic condition even though they are hydrophilic. We screened the natural, hydrophilic antifungal agents effectual at neutral pH by using rice- or wheat-based confectioneries as models, which have actually problems of contamination of fungus. PSH and ε-PL were shown to be effectiveness in those models. They have been known to show strong antimicrobial effects at neutral pH, but they were thought to be necessary to add a large amount into foods to inhibit the growth of fungus. In this study, we demonstrated that the PSH and PL could use as effective antifungal agents with small amount at a high sugar concentration conditions around neutral pH. They were considered to suit for the application to the confectioneries.

Genetic Characterization of Enterococcus Faecalis N1-33 Bacteriocin and Obtained of the Mutant Strain that Produce Many Bacteriocin by Novobiocin Agent Effect, its Merit as A Food Preservative in Steamed Rice Model

Enterococcus faecalis strain N1-33 produces a peptide that shows bacteriocin activity, enterocin MR10A (EntMR10A). We cloned and sequenced the structural gene of the EntMR10A locus (entMR10A), and the peripheral region of entMR10A was analyzed. Inverted repeat-like structure was found for at both ends of entMR10A and so that it suggested entMR10A of strain N1-33 could be formed from an insertion sequence. Attempting to eliminate the plasmid from strain N1-33 using the plasmid-curing agent novobiocin was obtained the mutant strain of N1-33 which seemed to overproduction of bacteriocin than the original strain, termed N41-51. The number of originated bacteriocin structural genes detected by real-time PCR showed that its level of the strain N41-51 was about twofold higher than that of N1-33, and correspondingly appeared to produce about twofold more bacteriocin compared with the original strain in these culture broth, respectively. This difference as a food preservative potential was examined whether it proves the same result in the actual food systems, by using steamed rice. The culture supernatant of strain N41-51 has confirmed to inhibit the growth of Bacillus cereus by significantly less amount added to steamed rice than that of N1-33. Practical Applications Besides having it with their usual meals, Japanese often eat steamed rice such as rice balls and in their lunch. The most important point we care at these cases is the food poisoning caused by Bacillus cereus, and thus, growth inhibition of B. cereus in steamed rice has been an important task for food industry. In this study, efficacy of the bacteriocin produced by Enterococcus faecalis N1-33 against B. cereus in steamed rice had shown. The difference in bacteriocin activity of the wild-type strain N1-33 and its mutant strain N41-51, which showed about twice as much bacteriocin production, was also reshown well in the actual food system. Also that, the high bacteriocin producing strain of N1-33, termed N41-51, could be obtained with a simple plasmid curing process.

Effect of NaCl/Monosodium Glutamate (MSG) Mixture on the Sensorial Properties and Quality Characteristics of Model Meat Products.

Sodium chloride is an important ingredient added to most of foods which contributes to flavor enhancement and food preservation but excess intake of sodium chloride may also cause various diseases such as heart diseases, osteoporosis and so on. Therefore, this study was carried out to investigate the effect of monosodium glutamate (MSG) as a salty flavor enhancer on the quality and sensorial properties of the NaCl/MSG complex and actual food system. For characterizing the spray-dried NaCl/MSG complex, surface dimension, morphology, rheology, and saltiness intensity were estimated by increasing MSG (0-2.0%) levels at a fixed NaCl concentration (2.0%). MSG levels had no effect of the characteristics of the NaCl/MSG complex, although the addition of MSG increased the surface dimension of the NaCl/MSG complex significantly (p<0.05). Furthermore, the effect of MSG on enhancing the salty flavor was not observed in the solution of the NaCl/MSG complex. In the case of an actual food system, model meat products (pork patties) were prepared by replacing NaCl with MSG. MSG enhanced the salty flavor, thereby increasing overall acceptability of pork patties. Replacement of NaCl with MSG (<1.0%) did not result in negative sensorial properties of pork patties, although quality deterioration such as high cooking loss was found. Nevertheless, MSG had a potential application in meat product formulation as a salty flavor enhancer or a partial NaCl replacer when meat products were supplemented with binding agents.

In situ antioxidant and antimicrobial activities of naturally occurring caffeic acid, p‐coumaric acid and rutin, using food systems

Three pure compounds that naturally occur in plants were of particular interest to our study regarding the possibility of using them as food preservatives: p-coumaric acid (found in peanuts, tomatoes, carrots, garlic, wine, vinegar, etc.), caffeic acid (found in argan oil, oats, wheat, rice and olive oil) and rutin (found in asparagus, citrus fruits, berries, apple, apricot, asparagus, beef and beer). In the following study we investigated in situ antioxidant and antimicrobial activities of three pure compounds, namely caffeic acid, p-coumaric acid and rutin, naturally occurring in plants. Two food systems were used in order to obtain information on how these compounds react in actual food systems rather than microbiological media. The results indicated good antioxidant activity in in situ food systems. For tested phenolic compounds it was further shown that they successively inhibited the development of the isolated food contaminant Staphylococcus aureus in chicken soup. Panelist found that organoleptic characteristics of chicken soup and pork meat improved after treatment with phenolics. Our findings alone, along with the potential use of phenolic compounds that are widespread in nature, may imply their potential use as preservatives in the food industry.

Investigation of heat induced reactions between lipid oxidation products and amino acids in lipid rich model systems and hazelnuts

This study aimed to investigate the contribution of lipid oxidation to non-enzymatic browning reactions in lipid rich model and actual food systems. Hazelnut oil and model reaction mixtures consisting of different amino acids were heated under certain conditions to determine possible lipid oxidation and non-enzymatic browning reaction products. In model systems, the Schiff base of 2,4-decadienal, its decarboxylated form, and reaction products formed after hydrolytic cleavage of the Schiff base or decarboxylated form were identified by high resolution mass spectrometry. No furosine was detected in hazelnuts after roasting at 160 °C while the concentration of free amino acids significantly decreased. 2,4-Decadienal reacted effectively with all amino acids studied through a Maillard type carbonyl-amine condensation pathway. (2E,4E)-Deca-2,4-dien-1-amine was identified as a typical reaction product in model systems and roasted hazelnuts. In lipid-rich foods like hazelnuts, lipid-derived carbonyls might be responsible for potential modifications of free and protein bound amino acids during heating.

Inhibition of enzymatic browning in actual food systems by the Maillard reaction products

The Maillard reaction occurring between amino acids and sugars produces neo-formed compounds having certain levels of antioxidant activity depending on the reaction conditions and the type of reactants. The objective of this study was to investigate enzymatic browning inhibition capacity of Maillard reaction products (MRPs) formed from different amino acids including arginine (Arg), histidine (His), lysine (Lys) and proline (Pro). The inhibitory effects of the MRPs on polyphenol oxidase (PPO) were determined. The total antioxidant capacity (TAC) of MRPs derived from different amino acids were in the order Arg > His > Lys > Pro. The TAC and PPO inhibition of MRPs were evaluated as a function of temperature (80-120 °C), time (1-6 h) and pH (2-12). Arg-Glc and His-Glc MRPs exhibited strong TAC and PPO inhibition. Increasing temperature (up to 100 °C) and time also increased TAC and PPO inhibition. Kinetics analysis indicated a mixed type inhibition of PPO by MRPs. The results indicate that the MRPs derived from Arg and His under certain reaction conditions significantly prevent enzymatic browning in actual food systems. The intermediate compounds capable of preventing enzymatic browning are reductones and dehydroreductones, as confirmed by liquid chromatographic-mass spectrometric analyses.

EFFECT OF ACID ADAPTATION ON THERMAL TOLERANCE OF ESCHERICHIA COLI O157:H7 AND SALMONELLA ENTERICA IN MEAT SERUM

ABSTRACTEscherichia coli O157:H7 and Salmonella were adapted to acidic environments by growing in tryptic soy broth with 1% glucose (TSB + 1%G). Thermal tolerance of acid‐adapted pathogens was evaluated in meat serum. Five‐strain cocktail of both bacteria were grown separately in TSB and TSB + 1%G for 24 h at 37C. Meat serum was prepared from irradiated ground beef, inoculated with either acid‐adapted or nonadapted E. coli O157:H7 and Salmonella, and heated at 58, 62 and 65C to determine D values. D values of acid‐adapted E. coli O157:H7 were higher (P &lt; 0.05) than nonadapted cells at 58, 62 and 65C. Significantly higher (P &lt; 0.05) D values of acid‐adapted Salmonella were observed at 58 and 62C, but not at 65C. D values were 22.46 and 10.59 min at 58C, 3.58 and 1.38 min at 62C, 1.02 and 0.75 min at 65C for acid‐adapted and nonadapted E. coli O157:H7, respectively. D values of acid‐adapted Salmonella were 9.36 min at 58C, 1.66 min at 62C and 1.14 min at 65C, whereas the nonadapted counterparts had D values of 6.44, 0.88 and 0.95 min at 58, 62 and 65C, respectively.PRACTICAL APPLICATIONSFoodborne pathogens exist in the environment in healthy and/or stressed forms and have the potential to contaminate food products. This research was conducted to determine the effectiveness of commonly used heat treatments to eliminate acid‐adapted Escherichia coli O157:H7 and Salmonella in ground beef. There is limited literature on the thermal tolerance of acid adaptation of foodborne pathogens in actual food systems and studies in the past have been conducted at mild heating temperatures, whereas effects of heating to temperatures that are more indicative of cooking temperatures have rarely been researched. This study stresses upon the need for regulatory agencies and large‐scale meat manufacturers to take into consideration the increased thermal tolerance of acid‐adapted pathogens, as healthy growing cultures in a laboratory medium may inaccurately represent their survival in natural food environment.

Estimation of water activity from pH and °Brix values of some food products

In this study, a predictive model for the estimation of water activity (aw25°C) as a function of pH (1.00–8.00) and °Brix (0–82.00) values of simulated food solutions (SFS) was developed, through response surface methodology. Response fit analyses resulted in a highly significant (pH<0.0001) square root polynomial model that can predict aw25°C of SFS in terms of pH and °Brix values within the defined variable ranges. The linear, quadratic and interactive influences of pH and °Brix on aw25°C were all significant (pH<0.0001). Model validations in SFS and in a number of actual food systems showed that the model had acceptable predictive performance, as indicated by the calculated accuracy and bias indices.

Thermal Tolerance of Acid-Adapted and Non-adaptedEscherichia coliO157:H7 andSalmonellain Ground Beef During Storage

Thermal tolerance of acid-adapted Escherichia coli O157:H7 or Salmonella in ground beef was evaluated during storage at 4 degrees C or -20 degrees C. Both pathogens were adapted to acidic conditions (pH approximately 4.6) by growing in tryptic soy broth supplemented with 1% glucose. A five-strain cocktail of E. coli O157:H7 or Salmonella was grown separately in TSB (pH approximately 6.6) and TSB + 1% glucose for 24 h at 37 degrees C to provide cells with or without acid adaptation. Irradiated ground beef was inoculated with either acid-adapted or non-adapted E. coli O157:H7 or Salmonella; the samples stored at 4 degrees C were subjected to heat treatment at 62 degrees C or 65 degrees C on days 1, 7, 14, 21, and 28, and the samples stored at -20 degrees C were subjected to heat treatment at 62 degrees C or 65 degrees C on days 1, 30, 60, 90, and 120. Decimal reduction time (D values) of the pathogens was determined as an indicator of thermal tolerance. Significantly higher D(62) values were observed on days 21 and 28 for non-adapted E. coli O157:H7 stored at 4 degrees C and on days 90 and 120 for non-adapted E. coli O157:H7 stored at -20 degrees C (P < 0.05). Higher D(62) values were observed on days 21 and 28 among non-adapted Salmonella strains stored at 4 degrees C and on day 28 for acid-adapted strains of Salmonella stored at 4 degrees C (P < 0.05). Higher D(62) values for acid-adapted strains of Salmonella stored at -20 degrees C were observed on days 30, 60, and 90 (P < 0.05), when while no differences were observed in the D(65) values of acid-adapted and non-adapted strains of E. coli O157:H7 and Salmonella throughout storage at both temperatures (P > 0.05). This suggests that acid adaptation of foodborne pathogens provides a certain level of protection against heat treatment at lower cooking temperatures, while at higher temperatures there were no observed differences between the sensitivity of acid-adapted and non-adapted strains in an actual food system over an extended period of refrigerated and frozen storage.

Red clover isoflavonoids as anthocyanin color enhancing agents in muscadine wine and juice

Isoflavonoid extracts from red clover ( Trifolium pratense) leaves were found to enhance overall color and stability of anthocyanin 3,5-diglucosides present in muscadine grape ( Vitis rotundifolia) juice and wine through intermolecular copigmentation reactions. Predominant isoflavonoids present in red clover included formononetin, biochanin A, and prunetin and were the major polyphenolics identified to influence anthocyanin color and stability. Since red clover isoflavonoids have poor water solubility characteristics, this allowed for removal of extraneous non-isoflavonoid compounds using hot water and subsequent extraction with ethanol. Isoflavonoid solubility was evaluated as a function of ethanol concentration with recoveries up to 57% found in 20% solutions. Changes in maximum absorbance, total soluble phenolics, isoflavonoids, and anthocyanins were evaluated in muscadine juice and wine following the addition of isoflavonoid extracts with maximum color enhancement found at an anthocyanin to cofactor ratio of 1:8, after which their solubility was prohibitive. Additionally, dried leaves and ethanolic extracts of red clover were added prior to and following fermentation of muscadine wine (11% ethanol) stimulating the natural copigmentation that takes place during red wine fermentation and aging processes. Once fermentation was complete, finished wines were evaluated over a 9-week storage period at 20 and 37 °C. Despite low levels of isoflavonoids present, color improvement and anthocyanin stability was observed in the wines during storage. Little information is available on copigmentation reactions occurring in actual food systems, yet red clover isoflavonoids proved to be novel and effective color enhancing compounds when used in low concentrations in young muscadine wines.

Cereal arabinoxylans: advances in structure and physicochemical properties

Arabinoxylans constitute a major fraction of cereal cell wall polysaccharides. They consist of a linear β-(1 → 4) linked xylan backbone to which α- l-arabinofuranose units are attached as side residues via α-(1 → 3) and/or α-(1 → 2) linkages. Several structural models have been put forward based on enzymic degradation studies and structure elucidation of oligosaccharides by NMR, methylation, and periodate oxidation techniques. These tentative models present different substitution patterns of arabinoses along the xylan chain. Cereal arabinoxylans exhibit a great deal of structural heterogeneity with respect to ratio of Araf Xylp , substitution pattern of arabinoses, content of feruloyl groups and molecular size. The conformation and physicochemical properties (viscosity, gelation potential, intermolecular association) of arabinoxylans in aqueous solutions are dependent on the molecular features of these polysaccharides; specific structure-property relationships have been established in model and actual food systems. Wheat and rye arabinoxylans are important functional ingredients in baked products affecting the mechanical properties of dough, as well as the texture and other end-product quality characteristics.

Proteins in Whey: Chemical, Physical, and Functional Properties

There is abundant information concerning the functional behavior of whey proteins in model systems. The data on functional properties reported by different researchers, however, reveal wide discrepancies in values. For example, in the case of comparable whey preparations, apparent solubilities may range from 10 to 100%; strength of gels from 0.3 to greater than 10 N, foam overruns from 250 to 1500%, and foam stabilities from 0.5 to 30 min. Many of the data are of limited value in assessing the true functional characteristics of different preparations, treatments, or processing effects. Reports to date are useful in indicating the relative behavior of different proteins; however, the data do not always predict the performance of such proteins in actual food systems. This reflects the fact that in foods, extensive interactions with other components may occur, resulting in modified behavior of the proteins. Harper, (1984) has advocated the testing of these various preparations in simulated food systems which should validly relate the behavior to performance in commercial systems. Emphasis on standardization of specific protocols, with regard to order of addition in ingredients, temperature, pH control, and amount of energy input during mixing, homogenization, emulsification, etc. deserves serious consideration. While this approach is justifiable in terms of providing valuable data to commercial users, it does not minimize the importance of examining these proteins in model systems where the physicochemical basis of each functional attribute can be described in molecular terms (Kinsella, 1987). Such information is necessary to expedite appropriate methods of processing in order to control compositional variability, extent of denatauration, and possible protein modification. In addition, rapid, reliable tests for routine quality assurance that can provide practical information concerning functional applications would be of great value. Whey protein preparations vary immensely in functional behavior and are presently relegated to limited use as functional ingredients in the food industry. This need not be the case since conventional and new technologies permit rigorous control of production protocols, e.g., careful control of heat treatments can result in the production of whey protein preparations with consistent, reliable functional properties (deWit, 1981, 1984; Harper, 1984; Morr, 1985). As the market for functional proteins continues to expand, the whey industry must seek the means to refine whey protein products; determine useful functional properties; develop standardized manufacturing protocols; demonstrate the effectiveness of whey as a functional ingredient; promote, and then market, whey on the basis of performance at competitive cost.